From: Willy Tarreau <w@1wt.eu>
Date: Mon, 30 Jun 2025 16:44:07 +0000 (+0200)
Subject: REGTESTS: restrict execution to a single thread group
X-Git-Tag: v3.3-dev3~58
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=48d5ef363d91e0eb9ab4b627170ef01ce3b75a57;p=thirdparty%2Fhaproxy.git

REGTESTS: restrict execution to a single thread group

When threads are enabled and running on a machine with multiple CCX
or multiple nodes, thread groups are now enabled since 3.3-dev2, causing
load-balancing algorithms to randomly fail due to incoming connections
spreading over multiple groups and using different load balancing indexes.

Let's just force "thread-groups 1" into all configs when threads are
enabled to avoid this.
---

diff --git a/reg-tests/balance/balance-hash-maxconn.vtc b/reg-tests/balance/balance-hash-maxconn.vtc
index 2edd797c06..1453ed34bf 100644
--- a/reg-tests/balance/balance-hash-maxconn.vtc
+++ b/reg-tests/balance/balance-hash-maxconn.vtc
@@ -21,6 +21,11 @@ server s1 {
 } -start
 
 haproxy h1 -arg "-L A" -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout server "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/balance/balance-hash-maxqueue.vtc b/reg-tests/balance/balance-hash-maxqueue.vtc
index 9f45f80fdf..a27d72f991 100644
--- a/reg-tests/balance/balance-hash-maxqueue.vtc
+++ b/reg-tests/balance/balance-hash-maxqueue.vtc
@@ -47,6 +47,11 @@ server s1 {
 } -start
 
 haproxy h1 -arg "-L A" -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout server "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/balance/balance-rr.vtc b/reg-tests/balance/balance-rr.vtc
index 908a4f9af3..c7ba0a0634 100644
--- a/reg-tests/balance/balance-rr.vtc
+++ b/reg-tests/balance/balance-rr.vtc
@@ -22,6 +22,11 @@ server s4 {
 } -repeat 2 -start
 
 haproxy h1 -arg "-L A" -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout server "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/balance/balance-uri-path-only.vtc b/reg-tests/balance/balance-uri-path-only.vtc
index 81b9107179..b7113dad63 100644
--- a/reg-tests/balance/balance-uri-path-only.vtc
+++ b/reg-tests/balance/balance-uri-path-only.vtc
@@ -22,6 +22,11 @@ server s4 {
 } -repeat 5 -start
 
 haproxy h1 -arg "-L A" -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout server "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/balance/balance-uri.vtc b/reg-tests/balance/balance-uri.vtc
index e67883567b..3bcdb7b4c3 100644
--- a/reg-tests/balance/balance-uri.vtc
+++ b/reg-tests/balance/balance-uri.vtc
@@ -22,6 +22,11 @@ server s4 {
 } -repeat 2 -start
 
 haproxy h1 -arg "-L A" -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout server "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/cache/basic.vtc b/reg-tests/cache/basic.vtc
index 377cbb3792..47f7637526 100644
--- a/reg-tests/cache/basic.vtc
+++ b/reg-tests/cache/basic.vtc
@@ -23,6 +23,11 @@ server s1 {
 } -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/cache/caching_rules.vtc b/reg-tests/cache/caching_rules.vtc
index ee85bf25ce..83ab09f543 100644
--- a/reg-tests/cache/caching_rules.vtc
+++ b/reg-tests/cache/caching_rules.vtc
@@ -113,6 +113,10 @@ server s2 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         # WT: limit false-positives causing "HTTP header incomplete" due to
         # idle server connections being randomly used and randomly expiring
         # under us.
diff --git a/reg-tests/cache/expires.vtc b/reg-tests/cache/expires.vtc
index d8f94d338e..d44b4d807e 100644
--- a/reg-tests/cache/expires.vtc
+++ b/reg-tests/cache/expires.vtc
@@ -39,6 +39,10 @@ server s3 {
 
 haproxy h1 -conf {
        global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
                # WT: limit false-positives causing "HTTP header incomplete" due to
                # idle server connections being randomly used and randomly expiring
                # under us.
diff --git a/reg-tests/cache/if-modified-since.vtc b/reg-tests/cache/if-modified-since.vtc
index 521a555ff8..373190dbee 100644
--- a/reg-tests/cache/if-modified-since.vtc
+++ b/reg-tests/cache/if-modified-since.vtc
@@ -39,6 +39,10 @@ server s1 {
 
 haproxy h1 -conf {
        global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
                # WT: limit false-positives causing "HTTP header incomplete" due to
                # idle server connections being randomly used and randomly expiring
                # under us.
diff --git a/reg-tests/cache/if-none-match.vtc b/reg-tests/cache/if-none-match.vtc
index 550b854da4..124e7eed44 100644
--- a/reg-tests/cache/if-none-match.vtc
+++ b/reg-tests/cache/if-none-match.vtc
@@ -24,6 +24,10 @@ server s1 {
 
 haproxy h1 -conf {
        global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
                # WT: limit false-positives causing "HTTP header incomplete" due to
                # idle server connections being randomly used and randomly expiring
                # under us.
diff --git a/reg-tests/cache/post_on_entry.vtc b/reg-tests/cache/post_on_entry.vtc
index 0b930ecc4a..06d9aec82f 100644
--- a/reg-tests/cache/post_on_entry.vtc
+++ b/reg-tests/cache/post_on_entry.vtc
@@ -21,6 +21,11 @@ server s1 {
 } -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
        defaults
                mode http
                timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/cache/sample_fetches.vtc b/reg-tests/cache/sample_fetches.vtc
index c2b99c20ca..133ef39d98 100644
--- a/reg-tests/cache/sample_fetches.vtc
+++ b/reg-tests/cache/sample_fetches.vtc
@@ -43,6 +43,10 @@ server s3 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         # WT: limit false-positives causing "HTTP header incomplete" due to
         # idle server connections being randomly used and randomly expiring
         # under us.
diff --git a/reg-tests/cache/vary.vtc b/reg-tests/cache/vary.vtc
index 494fe8f009..5a6e6986c1 100644
--- a/reg-tests/cache/vary.vtc
+++ b/reg-tests/cache/vary.vtc
@@ -165,6 +165,10 @@ server s2 {
 
 haproxy h1 -conf {
        global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
                # WT: limit false-positives causing "HTTP header incomplete" due to
                # idle server connections being randomly used and randomly expiring
                # under us.
diff --git a/reg-tests/cache/vary_accept_encoding.vtc b/reg-tests/cache/vary_accept_encoding.vtc
index c58c106e3e..6fe2d6f32f 100644
--- a/reg-tests/cache/vary_accept_encoding.vtc
+++ b/reg-tests/cache/vary_accept_encoding.vtc
@@ -91,6 +91,10 @@ server s1 {
 
 haproxy h1 -conf {
        global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
                # WT: limit false-positives causing "HTTP header incomplete" due to
                # idle server connections being randomly used and randomly expiring
                # under us.
diff --git a/reg-tests/checks/1be_40srv_odd_health_checks.vtc b/reg-tests/checks/1be_40srv_odd_health_checks.vtc
index e4c0ff2625..09bc70b787 100644
--- a/reg-tests/checks/1be_40srv_odd_health_checks.vtc
+++ b/reg-tests/checks/1be_40srv_odd_health_checks.vtc
@@ -56,6 +56,11 @@ server s38 {} -start
 server s39 {} -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         timeout client "${HAPROXY_TEST_TIMEOUT-5s}"
         timeout server "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/checks/40be_2srv_odd_health_checks.vtc b/reg-tests/checks/40be_2srv_odd_health_checks.vtc
index 4d67971ff4..4967045362 100644
--- a/reg-tests/checks/40be_2srv_odd_health_checks.vtc
+++ b/reg-tests/checks/40be_2srv_odd_health_checks.vtc
@@ -238,6 +238,11 @@ server s37 {} -start
 server s39 {} -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         timeout client "${HAPROXY_TEST_TIMEOUT-5s}"
         timeout server "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/checks/4be_1srv_health_checks.vtc b/reg-tests/checks/4be_1srv_health_checks.vtc
index 98f32d79e0..da993d394e 100644
--- a/reg-tests/checks/4be_1srv_health_checks.vtc
+++ b/reg-tests/checks/4be_1srv_health_checks.vtc
@@ -92,6 +92,11 @@ syslog S4 -level notice {
 
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         timeout client  "${HAPROXY_TEST_TIMEOUT-5s}"
         timeout server  "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/checks/4be_1srv_smtpchk_httpchk_layer47errors.vtc b/reg-tests/checks/4be_1srv_smtpchk_httpchk_layer47errors.vtc
index 58ee949756..770286d3e5 100644
--- a/reg-tests/checks/4be_1srv_smtpchk_httpchk_layer47errors.vtc
+++ b/reg-tests/checks/4be_1srv_smtpchk_httpchk_layer47errors.vtc
@@ -55,6 +55,11 @@ server s2 {
 } -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         timeout client "${HAPROXY_TEST_TIMEOUT-5s}"
         timeout server "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/checks/agent-check.vtc b/reg-tests/checks/agent-check.vtc
index 5cf51c658e..90b4b64cb8 100644
--- a/reg-tests/checks/agent-check.vtc
+++ b/reg-tests/checks/agent-check.vtc
@@ -15,6 +15,11 @@ server s1 {
 
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode tcp
         timeout client "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/checks/http-check-expect.vtc b/reg-tests/checks/http-check-expect.vtc
index 118eef6d81..c553e15b31 100644
--- a/reg-tests/checks/http-check-expect.vtc
+++ b/reg-tests/checks/http-check-expect.vtc
@@ -24,6 +24,11 @@ syslog S1 -level notice {
 } -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout client "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/checks/http-check-send.vtc b/reg-tests/checks/http-check-send.vtc
index 076aba7f91..d0e80ea010 100644
--- a/reg-tests/checks/http-check-send.vtc
+++ b/reg-tests/checks/http-check-send.vtc
@@ -108,6 +108,11 @@ syslog S6 -level notice {
 
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout client "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/checks/http-check.vtc b/reg-tests/checks/http-check.vtc
index 31ef87abb0..22a02901ec 100644
--- a/reg-tests/checks/http-check.vtc
+++ b/reg-tests/checks/http-check.vtc
@@ -90,6 +90,11 @@ syslog S1 -level notice {
 } -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout client "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/checks/http-monitor-uri.vtc b/reg-tests/checks/http-monitor-uri.vtc
index 26e6e8136b..37c6fed199 100644
--- a/reg-tests/checks/http-monitor-uri.vtc
+++ b/reg-tests/checks/http-monitor-uri.vtc
@@ -7,6 +7,11 @@ varnishtest "Test the HTTP directive monitor-uri"
 feature ignore_unknown_macro
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/checks/ldap-check.vtc b/reg-tests/checks/ldap-check.vtc
index 38204bf3b3..2329f681ca 100644
--- a/reg-tests/checks/ldap-check.vtc
+++ b/reg-tests/checks/ldap-check.vtc
@@ -50,6 +50,11 @@ syslog S4 -level notice {
 } -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode tcp
         timeout client "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/checks/mysql-check.vtc b/reg-tests/checks/mysql-check.vtc
index 3600138065..f2f6428001 100644
--- a/reg-tests/checks/mysql-check.vtc
+++ b/reg-tests/checks/mysql-check.vtc
@@ -63,6 +63,11 @@ syslog S5 -level notice {
 
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode tcp
         timeout client "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/checks/pgsql-check.vtc b/reg-tests/checks/pgsql-check.vtc
index 5003e7df10..79b9ea5da7 100644
--- a/reg-tests/checks/pgsql-check.vtc
+++ b/reg-tests/checks/pgsql-check.vtc
@@ -48,6 +48,11 @@ syslog S4 -level notice {
 } -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode tcp
         timeout client "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/checks/redis-check.vtc b/reg-tests/checks/redis-check.vtc
index 3c74c93e85..7008b26454 100644
--- a/reg-tests/checks/redis-check.vtc
+++ b/reg-tests/checks/redis-check.vtc
@@ -29,6 +29,11 @@ syslog S2 -level notice {
 
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode tcp
         timeout client "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/checks/smtp-check.vtc b/reg-tests/checks/smtp-check.vtc
index 6a5f7b79db..4f2ecd073c 100644
--- a/reg-tests/checks/smtp-check.vtc
+++ b/reg-tests/checks/smtp-check.vtc
@@ -64,6 +64,11 @@ syslog S5 -level notice {
 
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode tcp
         timeout client "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/checks/spop-check.vtc b/reg-tests/checks/spop-check.vtc
index 8a7fbd3add..cd0d3fe8d8 100644
--- a/reg-tests/checks/spop-check.vtc
+++ b/reg-tests/checks/spop-check.vtc
@@ -48,6 +48,11 @@ syslog S4 -level notice {
 } -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode tcp
         timeout client "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/checks/ssl-hello-check.vtc b/reg-tests/checks/ssl-hello-check.vtc
index a44b6e15cb..1bb16a2a81 100644
--- a/reg-tests/checks/ssl-hello-check.vtc
+++ b/reg-tests/checks/ssl-hello-check.vtc
@@ -24,6 +24,10 @@ syslog S3 -level notice {
 
 haproxy htst -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     .if !ssllib_name_startswith(AWS-LC)
         tune.ssl.default-dh-param 2048
     .endif
diff --git a/reg-tests/checks/tcp-check-client-hello.vtc b/reg-tests/checks/tcp-check-client-hello.vtc
index 435fec70f1..9ca9abd98a 100644
--- a/reg-tests/checks/tcp-check-client-hello.vtc
+++ b/reg-tests/checks/tcp-check-client-hello.vtc
@@ -16,6 +16,10 @@ syslog S_ok -level notice {
 
 haproxy htst -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         ssl-default-bind-options ssl-min-ver TLSv1.2 ssl-max-ver TLSv1.3
 
     defaults
diff --git a/reg-tests/checks/tcp-check-ssl.vtc b/reg-tests/checks/tcp-check-ssl.vtc
index 4020f73f5a..540637ed2f 100644
--- a/reg-tests/checks/tcp-check-ssl.vtc
+++ b/reg-tests/checks/tcp-check-ssl.vtc
@@ -29,6 +29,10 @@ syslog S4 -level notice {
 
 haproxy htst -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     .if !ssllib_name_startswith(AWS-LC)
         tune.ssl.default-dh-param 2048
     .endif
diff --git a/reg-tests/checks/tcp-check_min-recv.vtc b/reg-tests/checks/tcp-check_min-recv.vtc
index 83f4c6b913..5fade86099 100644
--- a/reg-tests/checks/tcp-check_min-recv.vtc
+++ b/reg-tests/checks/tcp-check_min-recv.vtc
@@ -30,6 +30,11 @@ server s2 {
 } -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
   defaults
     mode tcp
     timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/checks/tcp-check_multiple_ports.vtc b/reg-tests/checks/tcp-check_multiple_ports.vtc
index 356ddf61c1..753f154d2b 100644
--- a/reg-tests/checks/tcp-check_multiple_ports.vtc
+++ b/reg-tests/checks/tcp-check_multiple_ports.vtc
@@ -19,6 +19,11 @@ server s1 {
 } -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
   defaults
     mode tcp
     timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/checks/tcp-checks-socks4.vtc b/reg-tests/checks/tcp-checks-socks4.vtc
index 8a730f5424..0f297e4a67 100644
--- a/reg-tests/checks/tcp-checks-socks4.vtc
+++ b/reg-tests/checks/tcp-checks-socks4.vtc
@@ -30,6 +30,11 @@ syslog S1 -level notice {
 } -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode tcp
         timeout client "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/checks/tls_health_checks.vtc b/reg-tests/checks/tls_health_checks.vtc
index 9c3039f53e..6155b04ecc 100644
--- a/reg-tests/checks/tls_health_checks.vtc
+++ b/reg-tests/checks/tls_health_checks.vtc
@@ -34,6 +34,10 @@ syslog S1 -level notice {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     .if !ssllib_name_startswith(AWS-LC)
         tune.ssl.default-dh-param 2048
     .endif
@@ -85,6 +89,10 @@ syslog S6 -level notice {
 
 haproxy h2 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     .if !ssllib_name_startswith(AWS-LC)
         tune.ssl.default-dh-param 2048
     .endif
diff --git a/reg-tests/compression/basic.vtc b/reg-tests/compression/basic.vtc
index 78ca61b8d5..f1e088753b 100644
--- a/reg-tests/compression/basic.vtc
+++ b/reg-tests/compression/basic.vtc
@@ -177,6 +177,11 @@ server s1 {
 
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/compression/etags_conversion.vtc b/reg-tests/compression/etags_conversion.vtc
index 96e34bcf9c..57a9748b33 100644
--- a/reg-tests/compression/etags_conversion.vtc
+++ b/reg-tests/compression/etags_conversion.vtc
@@ -106,6 +106,10 @@ server s1 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         # WT: limit false-positives causing "HTTP header incomplete" due to
         # idle server connections being randomly used and randomly expiring
         # under us.
diff --git a/reg-tests/compression/lua_validation.vtc b/reg-tests/compression/lua_validation.vtc
index 2bbf3a1a50..11bae83775 100644
--- a/reg-tests/compression/lua_validation.vtc
+++ b/reg-tests/compression/lua_validation.vtc
@@ -8,6 +8,10 @@ feature ignore_unknown_macro
 
 haproxy h1 -conf {
 global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 	tune.lua.bool-sample-conversion normal
 	lua-load		${testdir}/lua_validation.lua
 
diff --git a/reg-tests/compression/min_size.vtc b/reg-tests/compression/min_size.vtc
index 52d0716690..cdf8f6e513 100644
--- a/reg-tests/compression/min_size.vtc
+++ b/reg-tests/compression/min_size.vtc
@@ -56,6 +56,10 @@ server s1 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         # WT: limit false-positives causing "HTTP header incomplete" due to
         # idle server connections being randomly used and randomly expiring
         # under us.
diff --git a/reg-tests/compression/vary.vtc b/reg-tests/compression/vary.vtc
index 489de30f64..b1e56432f2 100644
--- a/reg-tests/compression/vary.vtc
+++ b/reg-tests/compression/vary.vtc
@@ -111,6 +111,10 @@ server s2 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         # WT: limit false-positives causing "HTTP header incomplete" due to
         # idle server connections being randomly used and randomly expiring
         # under us.
diff --git a/reg-tests/connection/cli_src_dst.vtc b/reg-tests/connection/cli_src_dst.vtc
index 6809d3948a..5e878c647b 100644
--- a/reg-tests/connection/cli_src_dst.vtc
+++ b/reg-tests/connection/cli_src_dst.vtc
@@ -4,6 +4,11 @@ feature cmd "$HAPROXY_PROGRAM -cc 'version_atleast(2.5-dev0)'"
 feature ignore_unknown_macro
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/connection/dispatch.vtc b/reg-tests/connection/dispatch.vtc
index 16151a188a..9bb9f88f4a 100644
--- a/reg-tests/connection/dispatch.vtc
+++ b/reg-tests/connection/dispatch.vtc
@@ -13,6 +13,10 @@ server s2 {
 
 haproxy h1 -conf {
 global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     # this is needed since 3.3, and this test will be removed in 3.5.
     expose-deprecated-directives
 
diff --git a/reg-tests/connection/h2_glitches.vtc b/reg-tests/connection/h2_glitches.vtc
index 2bf542f04a..28281857c3 100644
--- a/reg-tests/connection/h2_glitches.vtc
+++ b/reg-tests/connection/h2_glitches.vtc
@@ -6,6 +6,11 @@ feature ignore_unknown_macro
 
 # haproxy frontend
 haproxy hap -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 	defaults
 		timeout client 30s
 		timeout server 30s
diff --git a/reg-tests/connection/http_reuse_aggressive.vtc b/reg-tests/connection/http_reuse_aggressive.vtc
index 571a974120..b37a19c6f6 100644
--- a/reg-tests/connection/http_reuse_aggressive.vtc
+++ b/reg-tests/connection/http_reuse_aggressive.vtc
@@ -3,6 +3,11 @@ varnishtest "Test the http-reuse aggressive mode"
 feature ignore_unknown_macro
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 	defaults
 		timeout client 30s
 		timeout server 30s
diff --git a/reg-tests/connection/http_reuse_always.vtc b/reg-tests/connection/http_reuse_always.vtc
index 75e60d4d42..78f86368e6 100644
--- a/reg-tests/connection/http_reuse_always.vtc
+++ b/reg-tests/connection/http_reuse_always.vtc
@@ -4,6 +4,11 @@ varnishtest "Test the http-reuse always mode"
 feature ignore_unknown_macro
 
 haproxy h1 -Ws -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 	defaults
 		timeout client 30s
 		timeout server 30s
diff --git a/reg-tests/connection/http_reuse_be_transparent.vtc b/reg-tests/connection/http_reuse_be_transparent.vtc
index 312c0c0d2c..d7df94a112 100644
--- a/reg-tests/connection/http_reuse_be_transparent.vtc
+++ b/reg-tests/connection/http_reuse_be_transparent.vtc
@@ -9,6 +9,10 @@ feature ignore_unknown_macro
 
 haproxy h1 -conf {
 	global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 		nbthread 1
 
 	defaults
diff --git a/reg-tests/connection/http_reuse_conn_hash.vtc b/reg-tests/connection/http_reuse_conn_hash.vtc
index a6c3605825..37fc0513ff 100644
--- a/reg-tests/connection/http_reuse_conn_hash.vtc
+++ b/reg-tests/connection/http_reuse_conn_hash.vtc
@@ -4,6 +4,11 @@ varnishtest "Test the http-reuse with special connection parameters"
 feature ignore_unknown_macro
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 	defaults
 		timeout client 30s
 		timeout server 30s
diff --git a/reg-tests/connection/http_reuse_dispatch.vtc b/reg-tests/connection/http_reuse_dispatch.vtc
index 50f804beee..c6f3c03dfa 100644
--- a/reg-tests/connection/http_reuse_dispatch.vtc
+++ b/reg-tests/connection/http_reuse_dispatch.vtc
@@ -8,6 +8,10 @@ feature ignore_unknown_macro
 
 haproxy h1 -conf {
 	global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 		nbthread 1
 
 	defaults
diff --git a/reg-tests/connection/http_reuse_never.vtc b/reg-tests/connection/http_reuse_never.vtc
index d04bdfe59a..ee4d59b2f3 100644
--- a/reg-tests/connection/http_reuse_never.vtc
+++ b/reg-tests/connection/http_reuse_never.vtc
@@ -3,6 +3,11 @@ varnishtest "Test the http-reuse never mode"
 feature ignore_unknown_macro
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 	defaults
 		timeout client 30s
 		timeout server 30s
diff --git a/reg-tests/connection/http_reuse_safe.vtc b/reg-tests/connection/http_reuse_safe.vtc
index c554694ab6..34ebadf3e8 100644
--- a/reg-tests/connection/http_reuse_safe.vtc
+++ b/reg-tests/connection/http_reuse_safe.vtc
@@ -3,6 +3,11 @@ varnishtest "Test the http-reuse safe mode"
 feature ignore_unknown_macro
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 	defaults
 		timeout client 30s
 		timeout server 30s
diff --git a/reg-tests/connection/proxy_protocol_random_fail.vtc b/reg-tests/connection/proxy_protocol_random_fail.vtc
index 93667decf6..9870d131be 100644
--- a/reg-tests/connection/proxy_protocol_random_fail.vtc
+++ b/reg-tests/connection/proxy_protocol_random_fail.vtc
@@ -24,6 +24,10 @@ syslog Slog_1 -repeat 8 -level info {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     .if !ssllib_name_startswith(AWS-LC)
         tune.ssl.default-dh-param 2048
     .endif
diff --git a/reg-tests/connection/proxy_protocol_send_generic.vtc b/reg-tests/connection/proxy_protocol_send_generic.vtc
index af42dd342e..b4f0a13196 100644
--- a/reg-tests/connection/proxy_protocol_send_generic.vtc
+++ b/reg-tests/connection/proxy_protocol_send_generic.vtc
@@ -3,6 +3,11 @@ varnishtest "Check that generic TLV IDs are sent properly"
 feature ignore_unknown_macro
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         log global
@@ -42,6 +47,11 @@ client c1 -connect ${h1_feS_sock} {
 
 # Ensure that we achieve the same via a default-server.
 haproxy h2 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         log global
diff --git a/reg-tests/connection/proxy_protocol_send_unique_id.vtc b/reg-tests/connection/proxy_protocol_send_unique_id.vtc
index b020ae850c..fc4c8d77a8 100644
--- a/reg-tests/connection/proxy_protocol_send_unique_id.vtc
+++ b/reg-tests/connection/proxy_protocol_send_unique_id.vtc
@@ -3,6 +3,11 @@ varnishtest "Check that the unique ID TLV is properly sent"
 feature ignore_unknown_macro
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
 	timeout client 30s
 	timeout server 30s
diff --git a/reg-tests/connection/proxy_protocol_send_unique_id_alpn.vtc b/reg-tests/connection/proxy_protocol_send_unique_id_alpn.vtc
index 7ea30a5a2b..ab650948a6 100644
--- a/reg-tests/connection/proxy_protocol_send_unique_id_alpn.vtc
+++ b/reg-tests/connection/proxy_protocol_send_unique_id_alpn.vtc
@@ -5,6 +5,11 @@ varnishtest "Check that the unique ID TLV is properly sent for servers with ALPN
 feature ignore_unknown_macro
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
 	timeout client 30s
 	timeout server 30s
diff --git a/reg-tests/connection/proxy_protocol_tlv_validation.vtc b/reg-tests/connection/proxy_protocol_tlv_validation.vtc
index cd4fcd9468..63c2b76448 100644
--- a/reg-tests/connection/proxy_protocol_tlv_validation.vtc
+++ b/reg-tests/connection/proxy_protocol_tlv_validation.vtc
@@ -6,6 +6,11 @@ feature ignore_unknown_macro
 # the client is reused, leading to connection resets.
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
@@ -39,6 +44,11 @@ client c1 -connect ${h1_fe1_sock} {
 } -run
 
 haproxy h2 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
@@ -76,6 +86,11 @@ client c2 -connect ${h2_fe1_sock} {
 } -run
 
 haproxy h3 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
@@ -108,6 +123,11 @@ client c3 -connect ${h3_fe1_sock} {
 } -run
 
 haproxy h4 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/connection/reverse_connect_full.vtc b/reg-tests/connection/reverse_connect_full.vtc
index cc88382ced..8fcadabe3b 100644
--- a/reg-tests/connection/reverse_connect_full.vtc
+++ b/reg-tests/connection/reverse_connect_full.vtc
@@ -10,6 +10,10 @@ server s1 {
 
 haproxy h_edge -conf {
 global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 	expose-experimental-directives
 
 defaults
@@ -33,6 +37,10 @@ backend be-reverse
 
 haproxy h_dev -conf {
 global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 	expose-experimental-directives
 
 defaults
diff --git a/reg-tests/connection/reverse_server.vtc b/reg-tests/connection/reverse_server.vtc
index 5cd77ca7bb..9a0d3e6ac4 100644
--- a/reg-tests/connection/reverse_server.vtc
+++ b/reg-tests/connection/reverse_server.vtc
@@ -7,6 +7,10 @@ barrier b1 cond 2
 
 haproxy h_edge -conf {
 global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 	expose-experimental-directives
 
 defaults
diff --git a/reg-tests/connection/reverse_server_name.vtc b/reg-tests/connection/reverse_server_name.vtc
index 3a24601743..a37307a225 100644
--- a/reg-tests/connection/reverse_server_name.vtc
+++ b/reg-tests/connection/reverse_server_name.vtc
@@ -8,6 +8,10 @@ barrier b1 cond 2
 
 haproxy h_edge -conf {
 global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 	expose-experimental-directives
 
 defaults
diff --git a/reg-tests/connection/tcp_to_http_upgrade.vtc b/reg-tests/connection/tcp_to_http_upgrade.vtc
index 0956f2cbdb..304bf5f3e4 100644
--- a/reg-tests/connection/tcp_to_http_upgrade.vtc
+++ b/reg-tests/connection/tcp_to_http_upgrade.vtc
@@ -42,6 +42,11 @@ server s1 {
 } -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         timeout client 30s
         timeout server 30s
diff --git a/reg-tests/contrib/prometheus.vtc b/reg-tests/contrib/prometheus.vtc
index 89d65d7b74..9efee4be2b 100644
--- a/reg-tests/contrib/prometheus.vtc
+++ b/reg-tests/contrib/prometheus.vtc
@@ -16,6 +16,11 @@ server s2 {
 }  -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
 	mode http
 	timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/converter/add_item.vtc b/reg-tests/converter/add_item.vtc
index 474ad7bf81..46ce5912df 100644
--- a/reg-tests/converter/add_item.vtc
+++ b/reg-tests/converter/add_item.vtc
@@ -9,6 +9,11 @@ server s1 {
 } -repeat 3 -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
 	mode http
 	timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/converter/be2dec.vtc b/reg-tests/converter/be2dec.vtc
index a0b71046bc..9b3db73b59 100644
--- a/reg-tests/converter/be2dec.vtc
+++ b/reg-tests/converter/be2dec.vtc
@@ -9,6 +9,11 @@ server s1 {
 } -repeat 3 -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
 	mode http
 	timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/converter/be2hex.vtc b/reg-tests/converter/be2hex.vtc
index 4cf3dc1dfc..133d5b866c 100644
--- a/reg-tests/converter/be2hex.vtc
+++ b/reg-tests/converter/be2hex.vtc
@@ -9,6 +9,11 @@ server s1 {
 } -repeat 3 -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
 	mode http
 	timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/converter/bytes.vtc b/reg-tests/converter/bytes.vtc
index 8abe401e55..c4a4889fdc 100644
--- a/reg-tests/converter/bytes.vtc
+++ b/reg-tests/converter/bytes.vtc
@@ -11,6 +11,11 @@ server s1 {
 } -repeat 1 -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 	defaults
 		mode http
 		timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
@@ -98,6 +103,11 @@ client c1 -connect ${h1_fe_sock} {
 # TEST - 2
 # negative starting index causes startup failure
 haproxy h2 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 	defaults
 		mode http
 		timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
@@ -118,6 +128,11 @@ haproxy h2 -conf {
 # TEST - 3
 # negative length causes startup failure
 haproxy h3 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 	defaults
 		mode http
 		timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
@@ -138,6 +153,11 @@ haproxy h3 -conf {
 # TEST - 4
 # 0 length causes startup failure
 haproxy h4 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 	defaults
 		mode http
 		timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/converter/digest.vtc b/reg-tests/converter/digest.vtc
index fff0ae398e..5c3435e2f1 100644
--- a/reg-tests/converter/digest.vtc
+++ b/reg-tests/converter/digest.vtc
@@ -10,6 +10,11 @@ server s1 {
 } -repeat 2 -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
 	mode http
 	timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/converter/field.vtc b/reg-tests/converter/field.vtc
index 3b1d8198e3..b3c99adf20 100644
--- a/reg-tests/converter/field.vtc
+++ b/reg-tests/converter/field.vtc
@@ -8,6 +8,11 @@ server s1 {
 } -repeat 3 -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
 	mode http
 	timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/converter/fix.vtc b/reg-tests/converter/fix.vtc
index f15c0c9249..5431a3a56d 100644
--- a/reg-tests/converter/fix.vtc
+++ b/reg-tests/converter/fix.vtc
@@ -53,6 +53,11 @@ server s2 {
 } -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode tcp
         timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/converter/hmac.vtc b/reg-tests/converter/hmac.vtc
index 13729f650c..12f1227ec4 100644
--- a/reg-tests/converter/hmac.vtc
+++ b/reg-tests/converter/hmac.vtc
@@ -10,6 +10,11 @@ server s1 {
 } -repeat 2 -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
 	mode http
 	timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/converter/iif.vtc b/reg-tests/converter/iif.vtc
index 2c0c517fbb..2cd7323e7e 100644
--- a/reg-tests/converter/iif.vtc
+++ b/reg-tests/converter/iif.vtc
@@ -8,6 +8,11 @@ server s1 {
 } -repeat 3 -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
 	mode http
 	timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/converter/json.vtc b/reg-tests/converter/json.vtc
index 1f37c9f1f7..b0dcf7b8b3 100644
--- a/reg-tests/converter/json.vtc
+++ b/reg-tests/converter/json.vtc
@@ -9,6 +9,11 @@ server s1 {
 } -repeat 2 -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
 	mode http
 	timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/converter/json_query.vtc b/reg-tests/converter/json_query.vtc
index 4ffaf11d56..087f7833bd 100644
--- a/reg-tests/converter/json_query.vtc
+++ b/reg-tests/converter/json_query.vtc
@@ -9,6 +9,10 @@ server s1 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         # WT: limit false-positives causing "HTTP header incomplete" due to
         # idle server connections being randomly used and randomly expiring
         # under us.
diff --git a/reg-tests/converter/mqtt.vtc b/reg-tests/converter/mqtt.vtc
index 3ef0d1fa75..2ab8ececc5 100644
--- a/reg-tests/converter/mqtt.vtc
+++ b/reg-tests/converter/mqtt.vtc
@@ -55,6 +55,11 @@ server s2 {
 } -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode tcp
         timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/converter/param.vtc b/reg-tests/converter/param.vtc
index 1633603823..c33dc64eab 100644
--- a/reg-tests/converter/param.vtc
+++ b/reg-tests/converter/param.vtc
@@ -8,6 +8,11 @@ server s1 {
 } -repeat 10 -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 	defaults
 	mode http
 	timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/converter/secure_memcmp.vtc b/reg-tests/converter/secure_memcmp.vtc
index dfda40ec37..b3ef4ecd34 100644
--- a/reg-tests/converter/secure_memcmp.vtc
+++ b/reg-tests/converter/secure_memcmp.vtc
@@ -16,6 +16,10 @@ server s2 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         # WT: limit false-positives causing "HTTP header incomplete" due to
         # idle server connections being randomly used and randomly expiring
         # under us.
diff --git a/reg-tests/converter/sha2.vtc b/reg-tests/converter/sha2.vtc
index b10e45e54b..3d7e7b1d36 100644
--- a/reg-tests/converter/sha2.vtc
+++ b/reg-tests/converter/sha2.vtc
@@ -10,6 +10,11 @@ server s1 {
 } -repeat 2 -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
 	mode http
 	timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/converter/url_dec.vtc b/reg-tests/converter/url_dec.vtc
index d5e317bb2c..8918778319 100644
--- a/reg-tests/converter/url_dec.vtc
+++ b/reg-tests/converter/url_dec.vtc
@@ -9,6 +9,11 @@ server s1 {
 } -repeat 2 -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
 	mode http
 	timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/converter/url_enc.vtc b/reg-tests/converter/url_enc.vtc
index f3e6271d55..f35b9f24c7 100644
--- a/reg-tests/converter/url_enc.vtc
+++ b/reg-tests/converter/url_enc.vtc
@@ -8,6 +8,11 @@ server s1 {
 } -repeat 2 -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
 	mode http
 	timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/converter/word.vtc b/reg-tests/converter/word.vtc
index acd46781f5..9ee5403eda 100644
--- a/reg-tests/converter/word.vtc
+++ b/reg-tests/converter/word.vtc
@@ -8,6 +8,11 @@ server s1 {
 } -repeat 3 -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
 	mode http
 	timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/filters/random-forwarding.vtc b/reg-tests/filters/random-forwarding.vtc
index 2ca483ea73..0db734007b 100644
--- a/reg-tests/filters/random-forwarding.vtc
+++ b/reg-tests/filters/random-forwarding.vtc
@@ -48,6 +48,11 @@ server s1 {
 } -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/http-capture/multiple_headers.vtc b/reg-tests/http-capture/multiple_headers.vtc
index 1ae210b65c..6c95c627ad 100644
--- a/reg-tests/http-capture/multiple_headers.vtc
+++ b/reg-tests/http-capture/multiple_headers.vtc
@@ -39,6 +39,11 @@ server s {
 } -start
 
 haproxy h -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout client "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/http-cookies/cookie_insert_indirect.vtc b/reg-tests/http-cookies/cookie_insert_indirect.vtc
index 6b86360ad7..297f561f7c 100644
--- a/reg-tests/http-cookies/cookie_insert_indirect.vtc
+++ b/reg-tests/http-cookies/cookie_insert_indirect.vtc
@@ -23,6 +23,10 @@ server s1 {
 
 haproxy h1 -conf {
 	global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         log ${S1_addr}:${S1_port} len 2048 local0 debug err
 
     defaults
diff --git a/reg-tests/http-cookies/h2_cookie_concat.vtc b/reg-tests/http-cookies/h2_cookie_concat.vtc
index f5ae9b9732..5f73d838cf 100644
--- a/reg-tests/http-cookies/h2_cookie_concat.vtc
+++ b/reg-tests/http-cookies/h2_cookie_concat.vtc
@@ -8,6 +8,11 @@ server s1 {
 } -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 	defaults
 		timeout client 30s
 		timeout server 30s
diff --git a/reg-tests/http-errorfiles/errorfiles.vtc b/reg-tests/http-errorfiles/errorfiles.vtc
index 1ace744fad..82b5847b9c 100644
--- a/reg-tests/http-errorfiles/errorfiles.vtc
+++ b/reg-tests/http-errorfiles/errorfiles.vtc
@@ -7,6 +7,11 @@ feature ignore_unknown_macro
 
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/http-errorfiles/http-error.vtc b/reg-tests/http-errorfiles/http-error.vtc
index 6d82f28280..43d1bcaf12 100644
--- a/reg-tests/http-errorfiles/http-error.vtc
+++ b/reg-tests/http-errorfiles/http-error.vtc
@@ -5,6 +5,11 @@ varnishtest "Test the http-error directive"
 feature ignore_unknown_macro
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     http-errors errors-1
         errorfile 400  ${testdir}/errors/400-1.http
         errorfile 403  ${testdir}/errors/403-1.http
diff --git a/reg-tests/http-errorfiles/http_deny_errors.vtc b/reg-tests/http-errorfiles/http_deny_errors.vtc
index befec708e2..6f8993c219 100644
--- a/reg-tests/http-errorfiles/http_deny_errors.vtc
+++ b/reg-tests/http-errorfiles/http_deny_errors.vtc
@@ -5,6 +5,11 @@ varnishtest "Test the custom errors for HTTP deny rules"
 feature ignore_unknown_macro
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     http-errors errors-1
         errorfile 400  ${testdir}/errors/400-1.http
         errorfile 403  ${testdir}/errors/403-1.http
diff --git a/reg-tests/http-errorfiles/http_errors.vtc b/reg-tests/http-errorfiles/http_errors.vtc
index 4bc2276741..a660279ab6 100644
--- a/reg-tests/http-errorfiles/http_errors.vtc
+++ b/reg-tests/http-errorfiles/http_errors.vtc
@@ -5,6 +5,11 @@ varnishtest "Test the errorfiles directive"
 feature ignore_unknown_macro
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     http-errors errors-1
         errorfile 400  ${testdir}/errors/400-1.http
         errorfile 403  ${testdir}/errors/403-1.http
diff --git a/reg-tests/http-errorfiles/http_return.vtc b/reg-tests/http-errorfiles/http_return.vtc
index b7750501c8..c0cb24ddb8 100644
--- a/reg-tests/http-errorfiles/http_return.vtc
+++ b/reg-tests/http-errorfiles/http_return.vtc
@@ -6,6 +6,11 @@ varnishtest "Test the HTTP return action with errorfiles"
 feature ignore_unknown_macro
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     http-errors errors-2
         errorfile 400 ${testdir}/errors/400-2.http
 
diff --git a/reg-tests/http-messaging/h1_host_normalization.vtc b/reg-tests/http-messaging/h1_host_normalization.vtc
index 909d525094..0d61127055 100644
--- a/reg-tests/http-messaging/h1_host_normalization.vtc
+++ b/reg-tests/http-messaging/h1_host_normalization.vtc
@@ -235,6 +235,11 @@ syslog S1 -level info {
 } -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/http-messaging/h1_request_target_validation.vtc b/reg-tests/http-messaging/h1_request_target_validation.vtc
index 3f008fef66..81e73c04b2 100644
--- a/reg-tests/http-messaging/h1_request_target_validation.vtc
+++ b/reg-tests/http-messaging/h1_request_target_validation.vtc
@@ -6,6 +6,10 @@ feature cmd "$HAPROXY_PROGRAM -cc 'version_atleast(3.0-dev0)'"
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         # WT: limit false-positives causing "HTTP header incomplete" due to
         # idle server connections being randomly used and randomly expiring
         # under us.
diff --git a/reg-tests/http-messaging/h1_to_h1.vtc b/reg-tests/http-messaging/h1_to_h1.vtc
index 67aba14409..090c798c03 100644
--- a/reg-tests/http-messaging/h1_to_h1.vtc
+++ b/reg-tests/http-messaging/h1_to_h1.vtc
@@ -115,6 +115,10 @@ server s1 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         # WT: limit false-positives causing "HTTP header incomplete" due to
         # idle server connections being randomly used and randomly expiring
         # under us.
diff --git a/reg-tests/http-messaging/h2_desync_attacks.vtc b/reg-tests/http-messaging/h2_desync_attacks.vtc
index c638f7d5b0..f77538b073 100644
--- a/reg-tests/http-messaging/h2_desync_attacks.vtc
+++ b/reg-tests/http-messaging/h2_desync_attacks.vtc
@@ -14,6 +14,11 @@ server s1 {
 
 # haproxy frontend
 haproxy hap -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 	defaults
 		timeout client 30s
 		timeout server 30s
diff --git a/reg-tests/http-messaging/h2_to_h1.vtc b/reg-tests/http-messaging/h2_to_h1.vtc
index 637b664866..e044b31626 100644
--- a/reg-tests/http-messaging/h2_to_h1.vtc
+++ b/reg-tests/http-messaging/h2_to_h1.vtc
@@ -42,6 +42,10 @@ server s1 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         # WT: limit false-positives causing "HTTP header incomplete" due to
         # idle server connections being randomly used and randomly expiring
         # under us.
diff --git a/reg-tests/http-messaging/http_abortonclose.vtc b/reg-tests/http-messaging/http_abortonclose.vtc
index ea57f3d6be..f9ad90621a 100644
--- a/reg-tests/http-messaging/http_abortonclose.vtc
+++ b/reg-tests/http-messaging/http_abortonclose.vtc
@@ -65,6 +65,10 @@ syslog S2 -level info {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         # WT: limit false-positives causing "HTTP header incomplete" due to
         # idle server connections being randomly used and randomly expiring
         # under us.
@@ -111,6 +115,10 @@ haproxy h1 -conf {
 
 haproxy h2 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         # WT: limit false-positives causing "HTTP header incomplete" due to
         # idle server connections being randomly used and randomly expiring
         # under us.
diff --git a/reg-tests/http-messaging/http_bodyless_response.vtc b/reg-tests/http-messaging/http_bodyless_response.vtc
index c470a97f73..e54782e374 100644
--- a/reg-tests/http-messaging/http_bodyless_response.vtc
+++ b/reg-tests/http-messaging/http_bodyless_response.vtc
@@ -30,6 +30,10 @@ server s1 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         # WT: limit false-positives causing "HTTP header incomplete" due to
         # idle server connections being randomly used and randomly expiring
         # under us.
diff --git a/reg-tests/http-messaging/http_bodyless_spliced_response.vtc b/reg-tests/http-messaging/http_bodyless_spliced_response.vtc
index b91809fd15..26d6033213 100644
--- a/reg-tests/http-messaging/http_bodyless_spliced_response.vtc
+++ b/reg-tests/http-messaging/http_bodyless_spliced_response.vtc
@@ -34,6 +34,10 @@ server s1 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         # WT: limit false-positives causing "HTTP header incomplete" due to
         # idle server connections being randomly used and randomly expiring
         # under us.
diff --git a/reg-tests/http-messaging/http_request_buffer.vtc b/reg-tests/http-messaging/http_request_buffer.vtc
index 302db4ab4e..a0f72dedef 100644
--- a/reg-tests/http-messaging/http_request_buffer.vtc
+++ b/reg-tests/http-messaging/http_request_buffer.vtc
@@ -40,6 +40,11 @@ syslog S -level info {
 } -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 	defaults
 		mode http
 		timeout client  100
diff --git a/reg-tests/http-messaging/http_splicing.vtc b/reg-tests/http-messaging/http_splicing.vtc
index e86680bd55..a86e2f77a8 100644
--- a/reg-tests/http-messaging/http_splicing.vtc
+++ b/reg-tests/http-messaging/http_splicing.vtc
@@ -24,6 +24,10 @@ server s2 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         log stderr len 4096 local0 debug
 
     defaults
diff --git a/reg-tests/http-messaging/http_splicing_chunk.vtc b/reg-tests/http-messaging/http_splicing_chunk.vtc
index e2e9f32ddd..99e0142d64 100644
--- a/reg-tests/http-messaging/http_splicing_chunk.vtc
+++ b/reg-tests/http-messaging/http_splicing_chunk.vtc
@@ -28,6 +28,10 @@ server s1 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         log stderr len 4096 local0 debug
 
     defaults
diff --git a/reg-tests/http-messaging/http_transfer_encoding.vtc b/reg-tests/http-messaging/http_transfer_encoding.vtc
index 322dfe29ac..a04a5f7651 100644
--- a/reg-tests/http-messaging/http_transfer_encoding.vtc
+++ b/reg-tests/http-messaging/http_transfer_encoding.vtc
@@ -77,6 +77,11 @@ server s2 {
 } -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/http-messaging/http_wait_for_body.vtc b/reg-tests/http-messaging/http_wait_for_body.vtc
index f0873166ff..11d6bcae72 100644
--- a/reg-tests/http-messaging/http_wait_for_body.vtc
+++ b/reg-tests/http-messaging/http_wait_for_body.vtc
@@ -69,6 +69,11 @@ server s2 {
 } -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout client  "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/http-messaging/protocol_upgrade.vtc b/reg-tests/http-messaging/protocol_upgrade.vtc
index ea66ebd505..46418a7491 100644
--- a/reg-tests/http-messaging/protocol_upgrade.vtc
+++ b/reg-tests/http-messaging/protocol_upgrade.vtc
@@ -138,6 +138,11 @@ server srv_h1_h2c {
 } -start
 
 haproxy hap -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 	defaults
 	mode http
 	timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/http-messaging/scheme_based_normalize.vtc b/reg-tests/http-messaging/scheme_based_normalize.vtc
index 3edbafbd10..53a3bec0be 100644
--- a/reg-tests/http-messaging/scheme_based_normalize.vtc
+++ b/reg-tests/http-messaging/scheme_based_normalize.vtc
@@ -18,6 +18,11 @@ syslog S1 -level info {
 } -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 	defaults
 		mode http
 		timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/http-messaging/srv_ws.vtc b/reg-tests/http-messaging/srv_ws.vtc
index 9969813334..5f1de0aea2 100644
--- a/reg-tests/http-messaging/srv_ws.vtc
+++ b/reg-tests/http-messaging/srv_ws.vtc
@@ -9,6 +9,11 @@ feature ignore_unknown_macro
 
 # haproxy server
 haproxy hapsrv -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 	defaults
 		mode http
 		timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
@@ -38,6 +43,11 @@ haproxy hapsrv -conf {
 
 # haproxy LB
 haproxy hap -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 	defaults
 		mode http
 		timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/http-messaging/truncated.vtc b/reg-tests/http-messaging/truncated.vtc
index a8048e1006..ca6d52abdd 100644
--- a/reg-tests/http-messaging/truncated.vtc
+++ b/reg-tests/http-messaging/truncated.vtc
@@ -61,6 +61,11 @@ server s1 {
 } -repeat 2 -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
 	#log stdout format raw daemon
 	mode http
diff --git a/reg-tests/http-messaging/websocket.vtc b/reg-tests/http-messaging/websocket.vtc
index a792a0b697..e21ddd5bbc 100644
--- a/reg-tests/http-messaging/websocket.vtc
+++ b/reg-tests/http-messaging/websocket.vtc
@@ -46,6 +46,11 @@ server s2 {
 # haproxy instance used as a server
 # generate a http/1.1 websocket response with the valid key
 haproxy hap_srv -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 	defaults
 	mode http
 	timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
@@ -68,6 +73,11 @@ haproxy hap_srv -conf {
 # haproxy instance used as a server
 # generate a http/1.1 websocket response with an invalid key
 haproxy hap_srv_bad_key -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 	defaults
 	mode http
 	timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
@@ -88,6 +98,11 @@ haproxy hap_srv_bad_key -conf {
 } -start
 
 haproxy hap -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 	defaults
 	mode http
 	timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/http-rules/acl_cli_spaces.vtc b/reg-tests/http-rules/acl_cli_spaces.vtc
index 8783f11a9f..90ba1d1076 100644
--- a/reg-tests/http-rules/acl_cli_spaces.vtc
+++ b/reg-tests/http-rules/acl_cli_spaces.vtc
@@ -9,6 +9,11 @@ server s1 {
 } -repeat 2 -start
 
 haproxy h1 -Ws -S -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
   defaults
     mode http
     timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/http-rules/converters_ipmask_concat_strcmp_field_word.vtc b/reg-tests/http-rules/converters_ipmask_concat_strcmp_field_word.vtc
index b2b8ae83ab..16596d0378 100644
--- a/reg-tests/http-rules/converters_ipmask_concat_strcmp_field_word.vtc
+++ b/reg-tests/http-rules/converters_ipmask_concat_strcmp_field_word.vtc
@@ -73,6 +73,11 @@ server s2 {
 
 # ipmask,hdr_ip tests with accept-proxy bind
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
   defaults
     mode http
     timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
@@ -132,6 +137,11 @@ haproxy h1 -conf {
 
 # concat,strcmp,word,field haproxy
 haproxy h2 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
   defaults
     mode http
     timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/http-rules/default_rules.vtc b/reg-tests/http-rules/default_rules.vtc
index cc726ab08f..647f29d96e 100644
--- a/reg-tests/http-rules/default_rules.vtc
+++ b/reg-tests/http-rules/default_rules.vtc
@@ -18,6 +18,11 @@ server s2 {
 }  -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
   defaults common
       mode http
       timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
@@ -58,6 +63,11 @@ haproxy h1 -conf {
 
 
 haproxy h2 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
   defaults common
       mode http
       timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
@@ -93,6 +103,11 @@ haproxy h2 -conf {
 } -start
 
 haproxy h3 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
   defaults base-http
       mode http
       timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/http-rules/del_header.vtc b/reg-tests/http-rules/del_header.vtc
index 0f74a606e1..cffcde81f5 100644
--- a/reg-tests/http-rules/del_header.vtc
+++ b/reg-tests/http-rules/del_header.vtc
@@ -34,6 +34,11 @@ server s1 {
 } -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/http-rules/except-forwardfor-originalto.vtc b/reg-tests/http-rules/except-forwardfor-originalto.vtc
index 211c1c109c..cb1f5a830b 100644
--- a/reg-tests/http-rules/except-forwardfor-originalto.vtc
+++ b/reg-tests/http-rules/except-forwardfor-originalto.vtc
@@ -7,6 +7,10 @@ feature ignore_unknown_macro
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         # WT: limit false-positives causing "HTTP header incomplete" due to
         # idle server connections being randomly used and randomly expiring
         # under us.
diff --git a/reg-tests/http-rules/forwarded-header-7239.vtc b/reg-tests/http-rules/forwarded-header-7239.vtc
index dd2c6e3fd0..a3e15e9f6e 100644
--- a/reg-tests/http-rules/forwarded-header-7239.vtc
+++ b/reg-tests/http-rules/forwarded-header-7239.vtc
@@ -8,6 +8,10 @@ feature ignore_unknown_macro
 #test: converters, parsing and header injection logic
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         # WT: limit false-positives causing "HTTP header incomplete" due to
         # idle server connections being randomly used and randomly expiring
         # under us.
@@ -55,6 +59,10 @@ haproxy h1 -conf {
 #test: "default" and "no option forwarded"
 haproxy h2 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         # WT: limit false-positives causing "HTTP header incomplete" due to
         # idle server connections being randomly used and randomly expiring
         # under us.
diff --git a/reg-tests/http-rules/h1or2_to_h1c.vtc b/reg-tests/http-rules/h1or2_to_h1c.vtc
index 89ae0f6a6f..f5e76da189 100644
--- a/reg-tests/http-rules/h1or2_to_h1c.vtc
+++ b/reg-tests/http-rules/h1or2_to_h1c.vtc
@@ -35,6 +35,11 @@ server s1 {
 } -repeat 2 -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
 	mode http
 	timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/http-rules/http-err-fail.vtc b/reg-tests/http-rules/http-err-fail.vtc
index 6d8f9ea3e8..7a504ac56b 100644
--- a/reg-tests/http-rules/http-err-fail.vtc
+++ b/reg-tests/http-rules/http-err-fail.vtc
@@ -26,6 +26,10 @@ server s5 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 	http-err-codes  220 +300-499 -300-399  # only 220, 400-499 remain
 	http-fail-codes -550-580 +555,599,556-566
 
diff --git a/reg-tests/http-rules/http_after_response.vtc b/reg-tests/http-rules/http_after_response.vtc
index 871cc27730..1bf4f0c436 100644
--- a/reg-tests/http-rules/http_after_response.vtc
+++ b/reg-tests/http-rules/http_after_response.vtc
@@ -19,6 +19,11 @@ server s1 {
 } -repeat 2 -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/http-rules/http_return.vtc b/reg-tests/http-rules/http_return.vtc
index ea4e95672e..dbbbe4a8e6 100644
--- a/reg-tests/http-rules/http_return.vtc
+++ b/reg-tests/http-rules/http_return.vtc
@@ -6,6 +6,10 @@ feature ignore_unknown_macro
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         # WT: limit false-positives causing "HTTP header incomplete" due to
         # idle server connections being randomly used and randomly expiring
         # under us.
diff --git a/reg-tests/http-rules/ifnone-forwardfor.vtc b/reg-tests/http-rules/ifnone-forwardfor.vtc
index a743b10b4e..699a9f6309 100644
--- a/reg-tests/http-rules/ifnone-forwardfor.vtc
+++ b/reg-tests/http-rules/ifnone-forwardfor.vtc
@@ -7,6 +7,10 @@ feature ignore_unknown_macro
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         # WT: limit false-positives causing "HTTP header incomplete" due to
         # idle server connections being randomly used and randomly expiring
         # under us.
diff --git a/reg-tests/http-rules/map_ordering.vtc b/reg-tests/http-rules/map_ordering.vtc
index 923d19fa58..f3e4fdafde 100644
--- a/reg-tests/http-rules/map_ordering.vtc
+++ b/reg-tests/http-rules/map_ordering.vtc
@@ -3,6 +3,11 @@ feature cmd "$HAPROXY_PROGRAM -cc 'version_atleast(2.5-dev0)'"
 feature ignore_unknown_macro
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
   defaults
     mode http
     timeout connect  "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/http-rules/map_redirect.vtc b/reg-tests/http-rules/map_redirect.vtc
index e8ed033639..bf58da8ee6 100644
--- a/reg-tests/http-rules/map_redirect.vtc
+++ b/reg-tests/http-rules/map_redirect.vtc
@@ -32,6 +32,11 @@ server s4 {
 } -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
   defaults
     mode http
     log global
diff --git a/reg-tests/http-rules/map_regm_with_backref.vtc b/reg-tests/http-rules/map_regm_with_backref.vtc
index c3b21fbde7..5f9ef04cbf 100644
--- a/reg-tests/http-rules/map_regm_with_backref.vtc
+++ b/reg-tests/http-rules/map_regm_with_backref.vtc
@@ -34,6 +34,10 @@ server s1 {
 
 haproxy h1 -conf {
   global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     log ${S1_addr}:${S1_port} local0 debug err
 
   defaults
diff --git a/reg-tests/http-rules/normalize_uri.vtc b/reg-tests/http-rules/normalize_uri.vtc
index 92325e6a14..6df9a9890c 100644
--- a/reg-tests/http-rules/normalize_uri.vtc
+++ b/reg-tests/http-rules/normalize_uri.vtc
@@ -11,6 +11,10 @@ server s1 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         # WT: limit false-positives causing "HTTP header incomplete" due to
         # idle server connections being randomly used and randomly expiring
         # under us.
diff --git a/reg-tests/http-rules/path_and_pathq.vtc b/reg-tests/http-rules/path_and_pathq.vtc
index 971cbe2d5d..2fd1f7ba6e 100644
--- a/reg-tests/http-rules/path_and_pathq.vtc
+++ b/reg-tests/http-rules/path_and_pathq.vtc
@@ -25,6 +25,11 @@ server s1 {
 } -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/http-rules/restrict_req_hdr_names.vtc b/reg-tests/http-rules/restrict_req_hdr_names.vtc
index 4b26e33c67..35e5dc0280 100644
--- a/reg-tests/http-rules/restrict_req_hdr_names.vtc
+++ b/reg-tests/http-rules/restrict_req_hdr_names.vtc
@@ -62,6 +62,11 @@ server s9 {
 } -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/http-rules/strict_rw_mode.vtc b/reg-tests/http-rules/strict_rw_mode.vtc
index 89a4548f7e..c0e592dde2 100644
--- a/reg-tests/http-rules/strict_rw_mode.vtc
+++ b/reg-tests/http-rules/strict_rw_mode.vtc
@@ -62,6 +62,10 @@ server s2 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         tune.bufsize 2048
         tune.maxrewrite 128
 
diff --git a/reg-tests/http-set-timeout/set_timeout.vtc b/reg-tests/http-set-timeout/set_timeout.vtc
index 7887f2abc7..4b4a43149a 100644
--- a/reg-tests/http-set-timeout/set_timeout.vtc
+++ b/reg-tests/http-set-timeout/set_timeout.vtc
@@ -53,6 +53,11 @@ syslog Slog9 -level info {
 } -start
 
 haproxy hap -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         timeout connect 5s
         timeout client 5s
diff --git a/reg-tests/jwt/jws_verify.vtc b/reg-tests/jwt/jws_verify.vtc
index f6951ec77a..c4309f85a0 100644
--- a/reg-tests/jwt/jws_verify.vtc
+++ b/reg-tests/jwt/jws_verify.vtc
@@ -23,6 +23,10 @@ server s1 -repeat 26 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     .if !ssllib_name_startswith(AWS-LC)
         tune.ssl.default-dh-param 2048
     .endif
diff --git a/reg-tests/log/load_balancing.vtc b/reg-tests/log/load_balancing.vtc
index 5c56e653dc..bef3388553 100644
--- a/reg-tests/log/load_balancing.vtc
+++ b/reg-tests/log/load_balancing.vtc
@@ -35,6 +35,10 @@ syslog Slg_2 -level info {
 
 haproxy h1 -conf {
 	global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 		nbthread 1
 
 	defaults
diff --git a/reg-tests/log/log_backend.vtc b/reg-tests/log/log_backend.vtc
index a9223ee01a..c3a83d947b 100644
--- a/reg-tests/log/log_backend.vtc
+++ b/reg-tests/log/log_backend.vtc
@@ -38,6 +38,11 @@ syslog Slg24 -level info {
 } -repeat 1 -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 	defaults
 		mode http
 		option httplog
diff --git a/reg-tests/log/log_forward.vtc b/reg-tests/log/log_forward.vtc
index 3977f4ca5d..f9da2937a4 100644
--- a/reg-tests/log/log_forward.vtc
+++ b/reg-tests/log/log_forward.vtc
@@ -13,6 +13,11 @@ syslog Slg1 -level info {
 } -repeat 50 -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 	defaults
 		mode http
 		option httplog
diff --git a/reg-tests/log/log_profiles.vtc b/reg-tests/log/log_profiles.vtc
index 0aeb338d4d..34da1c96ae 100644
--- a/reg-tests/log/log_profiles.vtc
+++ b/reg-tests/log/log_profiles.vtc
@@ -111,6 +111,11 @@ syslog Slg6 -level info {
 } -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 	defaults
 		timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
 		timeout client  "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/log/log_uri.vtc b/reg-tests/log/log_uri.vtc
index 753709d0e1..f16360c170 100644
--- a/reg-tests/log/log_uri.vtc
+++ b/reg-tests/log/log_uri.vtc
@@ -19,6 +19,10 @@ syslog Slg_1 -level info {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         nbthread 1
 
     defaults
diff --git a/reg-tests/log/wrong_ip_port_logging.vtc b/reg-tests/log/wrong_ip_port_logging.vtc
index 44312af9fe..8bc072aaca 100644
--- a/reg-tests/log/wrong_ip_port_logging.vtc
+++ b/reg-tests/log/wrong_ip_port_logging.vtc
@@ -35,6 +35,10 @@ syslog Slg_1 -level notice {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         log ${Slg_1_addr}:${Slg_1_port} local0
 
 defaults
diff --git a/reg-tests/lua/bad_http_clt_req_duration.vtc b/reg-tests/lua/bad_http_clt_req_duration.vtc
index ef15982a76..67c100b70f 100644
--- a/reg-tests/lua/bad_http_clt_req_duration.vtc
+++ b/reg-tests/lua/bad_http_clt_req_duration.vtc
@@ -35,6 +35,10 @@ syslog Slog {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         tune.lua.bool-sample-conversion normal
         lua-load ${testdir}/bad_http_clt_req_duration.lua
 
diff --git a/reg-tests/lua/close_wait_lf.vtc b/reg-tests/lua/close_wait_lf.vtc
index 9e2230a2cf..c5a0d18c7b 100644
--- a/reg-tests/lua/close_wait_lf.vtc
+++ b/reg-tests/lua/close_wait_lf.vtc
@@ -25,14 +25,18 @@ syslog Slog -level info -repeat 100 {
 } -start
 
 haproxy h1 -conf {
-    defaults
-        timeout client  "${HAPROXY_TEST_TIMEOUT-5s}"
-        timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
-
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         tune.lua.bool-sample-conversion normal
         lua-load ${testdir}/close_wait_lf.lua
 
+    defaults
+        timeout client  "${HAPROXY_TEST_TIMEOUT-5s}"
+        timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
+
     frontend frt
         log ${Slog_addr}:${Slog_port} local0 debug err
         log-format Ta=%Ta\ Tc=%Tc\ Td=%Td\ Th=%Th\ Ti=%Ti\ Tq=%Tq\ TR=%TR\ Tr=%Tr\ Tt=%Tt\ Tw=%Tw
diff --git a/reg-tests/lua/h_txn_get_priv.vtc b/reg-tests/lua/h_txn_get_priv.vtc
index 8a2931b5bd..43801bb5d9 100644
--- a/reg-tests/lua/h_txn_get_priv.vtc
+++ b/reg-tests/lua/h_txn_get_priv.vtc
@@ -5,6 +5,10 @@ feature ignore_unknown_macro
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         tune.lua.bool-sample-conversion normal
         lua-load ${testdir}/h_txn_get_priv.lua
 
diff --git a/reg-tests/lua/httpclient_action.vtc b/reg-tests/lua/httpclient_action.vtc
index 95baca0d8c..8939bdb803 100644
--- a/reg-tests/lua/httpclient_action.vtc
+++ b/reg-tests/lua/httpclient_action.vtc
@@ -12,6 +12,10 @@ feature ignore_unknown_macro
 haproxy h1 -conf {
 
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         tune.lua.bool-sample-conversion normal
         lua-load ${testdir}/httpclient_action.lua
     defaults
diff --git a/reg-tests/lua/lua_httpclient.vtc b/reg-tests/lua/lua_httpclient.vtc
index 996d991716..f83942605d 100644
--- a/reg-tests/lua/lua_httpclient.vtc
+++ b/reg-tests/lua/lua_httpclient.vtc
@@ -38,6 +38,10 @@ server s3 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         tune.lua.bool-sample-conversion normal
         lua-load ${testdir}/lua_httpclient.lua
 
diff --git a/reg-tests/lua/lua_socket.vtc b/reg-tests/lua/lua_socket.vtc
index b3b716ea97..b77ab0b86e 100644
--- a/reg-tests/lua/lua_socket.vtc
+++ b/reg-tests/lua/lua_socket.vtc
@@ -10,6 +10,10 @@ server s1 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         tune.lua.bool-sample-conversion normal
         lua-load ${testdir}/lua_socket.lua
 
diff --git a/reg-tests/lua/set_var.vtc b/reg-tests/lua/set_var.vtc
index 0d018fc4c0..bce4333321 100644
--- a/reg-tests/lua/set_var.vtc
+++ b/reg-tests/lua/set_var.vtc
@@ -5,12 +5,20 @@ feature ignore_unknown_macro
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         # WT: limit false-positives causing "HTTP header incomplete" due to
         # idle server connections being randomly used and randomly expiring
         # under us.
         tune.idle-pool.shared off
 
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         tune.lua.bool-sample-conversion normal
         lua-load ${testdir}/set_var.lua
 
diff --git a/reg-tests/lua/txn_get_priv-thread.vtc b/reg-tests/lua/txn_get_priv-thread.vtc
index 042404fafe..c58f93a55b 100644
--- a/reg-tests/lua/txn_get_priv-thread.vtc
+++ b/reg-tests/lua/txn_get_priv-thread.vtc
@@ -6,6 +6,10 @@ feature ignore_unknown_macro
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         # WT: limit false-positives causing "HTTP header incomplete" due to
         # idle server connections being randomly used and randomly expiring
         # under us.
diff --git a/reg-tests/lua/txn_get_priv.vtc b/reg-tests/lua/txn_get_priv.vtc
index 2951f110c0..24ac96252f 100644
--- a/reg-tests/lua/txn_get_priv.vtc
+++ b/reg-tests/lua/txn_get_priv.vtc
@@ -6,6 +6,10 @@ feature ignore_unknown_macro
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         tune.lua.bool-sample-conversion normal
         lua-load ${testdir}/txn_get_priv.lua
         lua-load ${testdir}/txn_get_priv-print_r.lua
diff --git a/reg-tests/lua/wrong_types_usage.vtc b/reg-tests/lua/wrong_types_usage.vtc
index f06b18a035..c394fc5669 100644
--- a/reg-tests/lua/wrong_types_usage.vtc
+++ b/reg-tests/lua/wrong_types_usage.vtc
@@ -43,6 +43,10 @@ server s1 -repeat 2 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         tune.lua.bool-sample-conversion normal
         lua-load ${testdir}/wrong_types_usage.lua
 
diff --git a/reg-tests/mailers/healthcheckmail.vtc b/reg-tests/mailers/healthcheckmail.vtc
index dbf4e9cc60..c23aa72735 100644
--- a/reg-tests/mailers/healthcheckmail.vtc
+++ b/reg-tests/mailers/healthcheckmail.vtc
@@ -12,6 +12,10 @@ syslog S1 -level notice {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         tune.lua.bool-sample-conversion normal
         lua-load ${testdir}/mailers.lua
         lua-load ${testdir}/healthcheckmail.lua
diff --git a/reg-tests/mcli/mcli_debug_dev.vtc b/reg-tests/mcli/mcli_debug_dev.vtc
index 0ecaa6202b..00879514ef 100644
--- a/reg-tests/mcli/mcli_debug_dev.vtc
+++ b/reg-tests/mcli/mcli_debug_dev.vtc
@@ -22,6 +22,10 @@ syslog S1 -level info {
 
 haproxy h1 -Ws -S -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 	log ${S1_addr}:${S1_port} local0 info
 
     defaults
diff --git a/reg-tests/mcli/mcli_show_info.vtc b/reg-tests/mcli/mcli_show_info.vtc
index 5c1949fd3b..5ee16110a3 100644
--- a/reg-tests/mcli/mcli_show_info.vtc
+++ b/reg-tests/mcli/mcli_show_info.vtc
@@ -8,6 +8,11 @@ server s1 {
 } -start
 
 haproxy h1 -Ws -S -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/peers/basic_sync.vtc b/reg-tests/peers/basic_sync.vtc
index 5c0cb4117c..f25e1f24a7 100644
--- a/reg-tests/peers/basic_sync.vtc
+++ b/reg-tests/peers/basic_sync.vtc
@@ -4,6 +4,11 @@ feature ignore_unknown_macro
 #REGTEST_TYPE=slow
 
 haproxy h1 -arg "-L A" -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         timeout client  "${HAPROXY_TEST_TIMEOUT-5s}"
         timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
@@ -26,6 +31,11 @@ haproxy h1 -arg "-L A" -conf {
 }
 
 haproxy h2 -arg "-L B" -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
 	mode http
         timeout client  "${HAPROXY_TEST_TIMEOUT-5s}"
@@ -48,6 +58,11 @@ haproxy h2 -arg "-L B" -conf {
 }
 
 haproxy h3 -arg "-L C" -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
 	mode http
         timeout client  "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/peers/basic_sync_wo_stkt_backend.vtc b/reg-tests/peers/basic_sync_wo_stkt_backend.vtc
index 9f97ff54e5..d9640ff0f4 100644
--- a/reg-tests/peers/basic_sync_wo_stkt_backend.vtc
+++ b/reg-tests/peers/basic_sync_wo_stkt_backend.vtc
@@ -4,6 +4,11 @@ feature ignore_unknown_macro
 #REGTEST_TYPE=slow
 
 haproxy h1 -arg "-L A" -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         timeout client  "${HAPROXY_TEST_TIMEOUT-5s}"
         timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
@@ -25,6 +30,11 @@ haproxy h1 -arg "-L A" -conf {
 }
 
 haproxy h2 -arg "-L B" -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout client  "${HAPROXY_TEST_TIMEOUT-5s}"
@@ -45,6 +55,11 @@ haproxy h2 -arg "-L B" -conf {
 }
 
 haproxy h3 -arg "-L C" -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout client  "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/peers/tls_basic_sync.vtc b/reg-tests/peers/tls_basic_sync.vtc
index 95e3d736e3..1618ef6db6 100644
--- a/reg-tests/peers/tls_basic_sync.vtc
+++ b/reg-tests/peers/tls_basic_sync.vtc
@@ -5,6 +5,11 @@ feature ignore_unknown_macro
 #REGTEST_TYPE=slow
 
 haproxy h1 -arg "-L A" -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         timeout client  "${HAPROXY_TEST_TIMEOUT-5s}"
         timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
@@ -29,6 +34,11 @@ haproxy h1 -arg "-L A" -conf {
 }
 
 haproxy h2 -arg "-L B" -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout client  "${HAPROXY_TEST_TIMEOUT-5s}"
@@ -53,6 +63,11 @@ haproxy h2 -arg "-L B" -conf {
 }
 
 haproxy h3 -arg "-L C" -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout client  "${HAPROXY_TEST_TIMEOUT-5s}"
@@ -77,6 +92,11 @@ haproxy h3 -arg "-L C" -conf {
 }
 
 haproxy h4 -arg "-L D" -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout client  "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/peers/tls_basic_sync_wo_stkt_backend.vtc b/reg-tests/peers/tls_basic_sync_wo_stkt_backend.vtc
index bf467084b8..2b5bcacbe0 100644
--- a/reg-tests/peers/tls_basic_sync_wo_stkt_backend.vtc
+++ b/reg-tests/peers/tls_basic_sync_wo_stkt_backend.vtc
@@ -5,6 +5,11 @@ feature ignore_unknown_macro
 #REGTEST_TYPE=slow
 
 haproxy h1 -arg "-L A" -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         timeout client  "${HAPROXY_TEST_TIMEOUT-5s}"
         timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
@@ -27,6 +32,11 @@ haproxy h1 -arg "-L A" -conf {
 }
 
 haproxy h2 -arg "-L B" -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout client  "${HAPROXY_TEST_TIMEOUT-5s}"
@@ -49,6 +59,11 @@ haproxy h2 -arg "-L B" -conf {
 }
 
 haproxy h3 -arg "-L C" -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout client  "${HAPROXY_TEST_TIMEOUT-5s}"
@@ -71,6 +86,11 @@ haproxy h3 -arg "-L C" -conf {
 }
 
 haproxy h4 -arg "-L D" -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout client  "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/sample_fetches/acl.vtc b/reg-tests/sample_fetches/acl.vtc
index 21e6f4b524..9d9289ceda 100644
--- a/reg-tests/sample_fetches/acl.vtc
+++ b/reg-tests/sample_fetches/acl.vtc
@@ -4,6 +4,11 @@ feature cmd "$HAPROXY_PROGRAM -cc 'version_atleast(2.9-dev2)'"
 feature ignore_unknown_macro
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/sample_fetches/cond_set_var.vtc b/reg-tests/sample_fetches/cond_set_var.vtc
index ea85d6cfb7..b45a6d1948 100644
--- a/reg-tests/sample_fetches/cond_set_var.vtc
+++ b/reg-tests/sample_fetches/cond_set_var.vtc
@@ -29,6 +29,10 @@ server s1 -repeat 10 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         set-var proc.int12 int(12)
         set-var proc.int5  var(proc.str60,60),div(proc.int12)
 
diff --git a/reg-tests/sample_fetches/cook.vtc b/reg-tests/sample_fetches/cook.vtc
index c1d26ada82..fc596eb737 100644
--- a/reg-tests/sample_fetches/cook.vtc
+++ b/reg-tests/sample_fetches/cook.vtc
@@ -10,6 +10,11 @@ server s1 {
 } -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
 	timeout client 30s
 	timeout server 30s
@@ -52,6 +57,11 @@ server s2 {
 } -start
 
 haproxy h2 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
 	timeout client 30s
 	timeout server 30s
@@ -84,6 +94,11 @@ server s3 {
 } -start
 
 haproxy h3 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
 	timeout client 30s
 	timeout server 30s
@@ -119,6 +134,11 @@ server s4 {
 } -start
 
 haproxy h4 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
 	timeout client 30s
 	timeout server 30s
diff --git a/reg-tests/sample_fetches/hashes.vtc b/reg-tests/sample_fetches/hashes.vtc
index e8f97b9d87..eeb8965034 100644
--- a/reg-tests/sample_fetches/hashes.vtc
+++ b/reg-tests/sample_fetches/hashes.vtc
@@ -8,6 +8,11 @@ server s1 {
 } -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/sample_fetches/so_name.vtc b/reg-tests/sample_fetches/so_name.vtc
index eea17b188f..7452e76a0e 100644
--- a/reg-tests/sample_fetches/so_name.vtc
+++ b/reg-tests/sample_fetches/so_name.vtc
@@ -3,6 +3,11 @@ varnishtest "so_name sample fetche Test"
 feature ignore_unknown_macro
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
 	timeout client 30s
 	timeout server 30s
diff --git a/reg-tests/sample_fetches/srv_name.vtc b/reg-tests/sample_fetches/srv_name.vtc
index 08233aac7b..62714a22da 100644
--- a/reg-tests/sample_fetches/srv_name.vtc
+++ b/reg-tests/sample_fetches/srv_name.vtc
@@ -13,6 +13,11 @@ server s2 {
 } -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/sample_fetches/tcpinfo_rtt.vtc b/reg-tests/sample_fetches/tcpinfo_rtt.vtc
index e21c542c0e..cfab9c59ab 100644
--- a/reg-tests/sample_fetches/tcpinfo_rtt.vtc
+++ b/reg-tests/sample_fetches/tcpinfo_rtt.vtc
@@ -9,6 +9,11 @@ server s1 {
 }  -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
   defaults common
       mode http
       timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/sample_fetches/tlvs.vtc b/reg-tests/sample_fetches/tlvs.vtc
index 9312b1df91..625f729e42 100644
--- a/reg-tests/sample_fetches/tlvs.vtc
+++ b/reg-tests/sample_fetches/tlvs.vtc
@@ -2,6 +2,11 @@ varnishtest "Tests for fetching PROXY protocol v2 TLVs"
 feature ignore_unknown_macro
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/sample_fetches/ubase64.vtc b/reg-tests/sample_fetches/ubase64.vtc
index dd7eefb7b6..aaada6f9aa 100644
--- a/reg-tests/sample_fetches/ubase64.vtc
+++ b/reg-tests/sample_fetches/ubase64.vtc
@@ -4,6 +4,10 @@ feature ignore_unknown_macro
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         # WT: limit false-positives causing "HTTP header incomplete" due to
         # idle server connections being randomly used and randomly expiring
         # under us.
diff --git a/reg-tests/sample_fetches/vars.vtc b/reg-tests/sample_fetches/vars.vtc
index 29d474cf2c..2019d58794 100644
--- a/reg-tests/sample_fetches/vars.vtc
+++ b/reg-tests/sample_fetches/vars.vtc
@@ -5,6 +5,10 @@ feature ignore_unknown_macro
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         # note below, str60 is purposely not defined so that the default is used
         set-var proc.int12 int(12)
         set-var proc.int5  var(proc.str60,60),div(proc.int12)
diff --git a/reg-tests/seamless-reload/abns_socket.vtc b/reg-tests/seamless-reload/abns_socket.vtc
index 0e8a7f3d72..9cc59a0990 100644
--- a/reg-tests/seamless-reload/abns_socket.vtc
+++ b/reg-tests/seamless-reload/abns_socket.vtc
@@ -25,6 +25,10 @@ feature cmd "command -v grep"
 
 haproxy h1 -Ws -S -conf {
   global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     stats socket "${tmpdir}/h1/stats" level admin expose-fd listeners
 
   defaults
diff --git a/reg-tests/server/abnsz.vtc b/reg-tests/server/abnsz.vtc
index e1f3b1a715..d296918f1a 100644
--- a/reg-tests/server/abnsz.vtc
+++ b/reg-tests/server/abnsz.vtc
@@ -8,6 +8,10 @@ feature cmd "command -v curl"
 
 haproxy h1 -Ws -S -conf {
   global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     stats socket "${tmpdir}/h1/stats" level admin expose-fd listeners
 
   defaults
diff --git a/reg-tests/server/cli_add_check_server.vtc b/reg-tests/server/cli_add_check_server.vtc
index e5b26d76bd..bd1157e4e1 100644
--- a/reg-tests/server/cli_add_check_server.vtc
+++ b/reg-tests/server/cli_add_check_server.vtc
@@ -64,6 +64,10 @@ syslog S1 -level notice {
 
 haproxy h1 -conf {
 	global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 		stats socket "${tmpdir}/h1/stats" level admin
 
 	defaults
diff --git a/reg-tests/server/cli_add_server.vtc b/reg-tests/server/cli_add_server.vtc
index 5722454367..8081312ba9 100644
--- a/reg-tests/server/cli_add_server.vtc
+++ b/reg-tests/server/cli_add_server.vtc
@@ -8,6 +8,11 @@ server s1 {
 } -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 	defaults
 		mode http
 		timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/server/cli_add_ssl_server.vtc b/reg-tests/server/cli_add_ssl_server.vtc
index 48faee13cc..bfff7af7d2 100644
--- a/reg-tests/server/cli_add_ssl_server.vtc
+++ b/reg-tests/server/cli_add_ssl_server.vtc
@@ -25,6 +25,10 @@ syslog S1 -level notice {
 
 haproxy h1 -conf {
 	global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 		stats socket "${tmpdir}/h1/stats" level admin
 
 	defaults
diff --git a/reg-tests/server/cli_add_track_server.vtc b/reg-tests/server/cli_add_track_server.vtc
index 2377fb2e48..28964bc5a2 100644
--- a/reg-tests/server/cli_add_track_server.vtc
+++ b/reg-tests/server/cli_add_track_server.vtc
@@ -91,6 +91,10 @@ syslog S3 {
 
 haproxy h1 -conf {
 	global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 		stats socket "${tmpdir}/h1/stats" level admin
 
 	defaults
diff --git a/reg-tests/server/cli_delete_dynamic_server.vtc b/reg-tests/server/cli_delete_dynamic_server.vtc
index ef3ef3ff18..78245ac649 100644
--- a/reg-tests/server/cli_delete_dynamic_server.vtc
+++ b/reg-tests/server/cli_delete_dynamic_server.vtc
@@ -20,6 +20,11 @@ server s2 -repeat 3 {
 } -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 	defaults
 		mode http
 		timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/server/cli_delete_server.vtc b/reg-tests/server/cli_delete_server.vtc
index 61d241c2af..7effb2d47d 100644
--- a/reg-tests/server/cli_delete_server.vtc
+++ b/reg-tests/server/cli_delete_server.vtc
@@ -7,6 +7,11 @@ feature cmd "$HAPROXY_PROGRAM -cc 'version_atleast(2.5-dev0)'"
 feature ignore_unknown_macro
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 	defaults
 		mode http
 		timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/server/cli_set_fqdn.vtc b/reg-tests/server/cli_set_fqdn.vtc
index f82674f30e..72695769fa 100644
--- a/reg-tests/server/cli_set_fqdn.vtc
+++ b/reg-tests/server/cli_set_fqdn.vtc
@@ -10,6 +10,11 @@ server s1 {
 } -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
@@ -25,6 +30,11 @@ haproxy h1 -conf {
 } -start
 
 haproxy h2 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/server/cli_set_ssl.vtc b/reg-tests/server/cli_set_ssl.vtc
index d05021d4d2..3f35d0921a 100644
--- a/reg-tests/server/cli_set_ssl.vtc
+++ b/reg-tests/server/cli_set_ssl.vtc
@@ -12,6 +12,10 @@ server s1 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         ssl-server-verify none
 
     defaults
diff --git a/reg-tests/spoe/wrong_init.vtc b/reg-tests/spoe/wrong_init.vtc
index 152622c5e4..6b2a218e36 100644
--- a/reg-tests/spoe/wrong_init.vtc
+++ b/reg-tests/spoe/wrong_init.vtc
@@ -12,6 +12,11 @@ varnishtest "SPOE bug: missing configuration file"
 feature ignore_unknown_macro
 
 haproxy h1 -conf-BAD {} {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 	defaults
         timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
         timeout client  "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/ssl/add_ssl_crt-list.vtc b/reg-tests/ssl/add_ssl_crt-list.vtc
index 6c6379ec33..5dd2d9506b 100644
--- a/reg-tests/ssl/add_ssl_crt-list.vtc
+++ b/reg-tests/ssl/add_ssl_crt-list.vtc
@@ -22,6 +22,10 @@ server s1 -repeat 2 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     .if !ssllib_name_startswith(AWS-LC)
         tune.ssl.default-dh-param 2048
     .endif
diff --git a/reg-tests/ssl/crt_store.vtc b/reg-tests/ssl/crt_store.vtc
index a07ec4e2a2..eecdcc45d0 100644
--- a/reg-tests/ssl/crt_store.vtc
+++ b/reg-tests/ssl/crt_store.vtc
@@ -11,6 +11,11 @@ feature ignore_unknown_macro
 
 
 haproxy h1 -arg -V -conf-OK {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     crt-store
        load crt "${testdir}/common.crt" key "${testdir}/common.key"
 
diff --git a/reg-tests/ssl/del_ssl_crt-list.vtc b/reg-tests/ssl/del_ssl_crt-list.vtc
index d711475eae..df0a51a21c 100644
--- a/reg-tests/ssl/del_ssl_crt-list.vtc
+++ b/reg-tests/ssl/del_ssl_crt-list.vtc
@@ -20,6 +20,10 @@ server s1 -repeat 2 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     .if !ssllib_name_startswith(AWS-LC)
         tune.ssl.default-dh-param 2048
     .endif
diff --git a/reg-tests/ssl/dynamic_server_ssl.vtc b/reg-tests/ssl/dynamic_server_ssl.vtc
index 6c79b6d9a3..2529e9450f 100644
--- a/reg-tests/ssl/dynamic_server_ssl.vtc
+++ b/reg-tests/ssl/dynamic_server_ssl.vtc
@@ -18,6 +18,10 @@ server s1 -repeat 3 {
 
 haproxy h1 -conf {
 	global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 		stats socket "${tmpdir}/h1/stats" level admin
 
 	defaults
diff --git a/reg-tests/ssl/issuers_chain_path.vtc b/reg-tests/ssl/issuers_chain_path.vtc
index 9fa90673f6..ee63b9a1ea 100644
--- a/reg-tests/ssl/issuers_chain_path.vtc
+++ b/reg-tests/ssl/issuers_chain_path.vtc
@@ -9,6 +9,10 @@ feature ignore_unknown_macro
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         stats socket "${tmpdir}/h1/stats" level admin
         issuers-chain-path "${testdir}/issuers-chain-path/ca/"
         crt-base "${testdir}/issuers-chain-path"
diff --git a/reg-tests/ssl/log_forward_ssl.vtc b/reg-tests/ssl/log_forward_ssl.vtc
index 6b7515bf87..0d59780ded 100644
--- a/reg-tests/ssl/log_forward_ssl.vtc
+++ b/reg-tests/ssl/log_forward_ssl.vtc
@@ -15,6 +15,10 @@ syslog Slg1 -level info {
 
 haproxy h1 -conf {
 	global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 		insecure-fork-wanted
 	defaults
 		mode http
diff --git a/reg-tests/ssl/new_del_ssl_cafile.vtc b/reg-tests/ssl/new_del_ssl_cafile.vtc
index 7e8a9f19d0..f81bf7ee0a 100644
--- a/reg-tests/ssl/new_del_ssl_cafile.vtc
+++ b/reg-tests/ssl/new_del_ssl_cafile.vtc
@@ -21,6 +21,10 @@ server s1 -repeat 2 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     .if !ssllib_name_startswith(AWS-LC)
         tune.ssl.default-dh-param 2048
     .endif
diff --git a/reg-tests/ssl/new_del_ssl_crlfile.vtc b/reg-tests/ssl/new_del_ssl_crlfile.vtc
index 8575f26449..42bc088101 100644
--- a/reg-tests/ssl/new_del_ssl_crlfile.vtc
+++ b/reg-tests/ssl/new_del_ssl_crlfile.vtc
@@ -21,6 +21,10 @@ server s1 -repeat 3 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     .if !ssllib_name_startswith(AWS-LC)
         tune.ssl.default-dh-param 2048
     .endif
diff --git a/reg-tests/ssl/ocsp_auto_update.vtc b/reg-tests/ssl/ocsp_auto_update.vtc
index f766309675..7101497941 100644
--- a/reg-tests/ssl/ocsp_auto_update.vtc
+++ b/reg-tests/ssl/ocsp_auto_update.vtc
@@ -47,6 +47,10 @@ feature ignore_unknown_macro
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     .if !ssllib_name_startswith(AWS-LC)
         tune.ssl.default-dh-param 2048
     .endif
@@ -117,6 +121,10 @@ syslog Syslog_ocsp -level notice {
 
 haproxy h2 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     .if !ssllib_name_startswith(AWS-LC)
         tune.ssl.default-dh-param 2048
     .endif
@@ -186,6 +194,10 @@ syslog Syslog_ocsp3 -level notice {
 
 haproxy h3 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     .if !ssllib_name_startswith(AWS-LC)
         tune.ssl.default-dh-param 2048
     .endif
@@ -260,6 +272,10 @@ syslog Syslog_ocsp4 -level notice {
 
 haproxy h4 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     .if !ssllib_name_startswith(AWS-LC)
         tune.ssl.default-dh-param 2048
     .endif
@@ -376,6 +392,10 @@ syslog Syslog_ocsp5 -level notice {
 
 haproxy h5 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     .if !ssllib_name_startswith(AWS-LC)
         tune.ssl.default-dh-param 2048
     .endif
@@ -460,6 +480,10 @@ syslog Syslog_ocsp6 -level notice {
 
 haproxy h6 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     .if !ssllib_name_startswith(AWS-LC)
         tune.ssl.default-dh-param 2048
     .endif
@@ -538,6 +562,10 @@ syslog Syslog_ocsp7 -level notice {
 
 haproxy h7 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     .if !ssllib_name_startswith(AWS-LC)
         tune.ssl.default-dh-param 2048
     .endif
@@ -603,6 +631,10 @@ process p7 -wait
 
 haproxy h8 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     .if !ssllib_name_startswith(AWS-LC)
         tune.ssl.default-dh-param 2048
     .endif
@@ -699,6 +731,10 @@ syslog Syslog_ocsp9 -level notice {
 
 haproxy h9 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     .if !ssllib_name_startswith(AWS-LC)
         tune.ssl.default-dh-param 2048
     .endif
diff --git a/reg-tests/ssl/ocsp_compat_check.vtc b/reg-tests/ssl/ocsp_compat_check.vtc
index f96fedef4c..2768821aa4 100644
--- a/reg-tests/ssl/ocsp_compat_check.vtc
+++ b/reg-tests/ssl/ocsp_compat_check.vtc
@@ -36,6 +36,10 @@ EOF
 
     cat << EOF > ${tmpdir}/ocsp_compat_check.cfg
 global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     crt-base ${testdir}/ocsp_update/multicert
 #    ocsp-update.mode on
 
@@ -67,6 +71,10 @@ EOF
 
     cat << EOF > ${tmpdir}/ocsp_compat_check.cfg
 global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     crt-base ${testdir}/ocsp_update/multicert
     ocsp-update.mode on
 
@@ -98,6 +106,10 @@ EOF
 
     cat << EOF > ${tmpdir}/ocsp_compat_check.cfg
 global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     crt-base ${testdir}/ocsp_update/multicert
     ocsp-update.mode off
 
@@ -129,6 +141,10 @@ EOF
 
     cat << EOF > ${tmpdir}/ocsp_compat_check.cfg
 global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     crt-base ${testdir}/ocsp_update/multicert
 #    ocsp-update.mode off
 
@@ -161,6 +177,10 @@ EOF
 
     cat << EOF > ${tmpdir}/ocsp_compat_check.cfg
 global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     crt-base ${testdir}/ocsp_update/multicert
     ocsp-update.mode on
 
@@ -193,6 +213,10 @@ EOF
 
     cat << EOF > ${tmpdir}/ocsp_compat_check.cfg
 global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     crt-base ${testdir}/ocsp_update/multicert
     ocsp-update.mode off
 
@@ -227,6 +251,10 @@ EOF
 
     cat << EOF > ${tmpdir}/ocsp_compat_check.cfg
 global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     crt-base ${testdir}/ocsp_update/multicert
 #    ocsp-update.mode off
 
@@ -259,6 +287,10 @@ EOF
 
     cat << EOF > ${tmpdir}/ocsp_compat_check.cfg
 global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     crt-base ${testdir}/ocsp_update/multicert
 #    ocsp-update.mode off
 
@@ -292,6 +324,10 @@ EOF
 
     cat << EOF > ${tmpdir}/ocsp_compat_check.cfg
 global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     crt-base ${testdir}/ocsp_update/multicert
     ocsp-update.mode on
 
@@ -325,6 +361,10 @@ EOF
 
     cat << EOF > ${tmpdir}/ocsp_compat_check.cfg
 global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     crt-base ${testdir}/ocsp_update/multicert
     ocsp-update.mode on
 
@@ -358,6 +398,10 @@ EOF
 
     cat << EOF > ${tmpdir}/ocsp_compat_check.cfg
 global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     crt-base ${testdir}/ocsp_update/multicert
     ocsp-update.mode off
 
@@ -391,6 +435,10 @@ EOF
 
     cat << EOF > ${tmpdir}/ocsp_compat_check.cfg
 global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     crt-base ${testdir}/ocsp_update/multicert
     ocsp-update.mode off
 
diff --git a/reg-tests/ssl/set_ssl_bug_2265.vtc b/reg-tests/ssl/set_ssl_bug_2265.vtc
index c773f134ca..2bd8652b34 100644
--- a/reg-tests/ssl/set_ssl_bug_2265.vtc
+++ b/reg-tests/ssl/set_ssl_bug_2265.vtc
@@ -25,6 +25,10 @@ server s1 -repeat 3 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     .if !ssllib_name_startswith(AWS-LC)
         tune.ssl.default-dh-param 2048
     .endif
diff --git a/reg-tests/ssl/set_ssl_cafile.vtc b/reg-tests/ssl/set_ssl_cafile.vtc
index 2e5aebbdaa..897fe5e407 100644
--- a/reg-tests/ssl/set_ssl_cafile.vtc
+++ b/reg-tests/ssl/set_ssl_cafile.vtc
@@ -27,6 +27,10 @@ server s1 -repeat 4 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     .if !ssllib_name_startswith(AWS-LC)
         tune.ssl.default-dh-param 2048
     .endif
diff --git a/reg-tests/ssl/set_ssl_cert.vtc b/reg-tests/ssl/set_ssl_cert.vtc
index 6373498dee..bdc5fba59e 100644
--- a/reg-tests/ssl/set_ssl_cert.vtc
+++ b/reg-tests/ssl/set_ssl_cert.vtc
@@ -31,6 +31,10 @@ server s1 -repeat 9 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     .if !ssllib_name_startswith(AWS-LC)
         tune.ssl.default-dh-param 2048
     .endif
diff --git a/reg-tests/ssl/set_ssl_cert_bundle.vtc b/reg-tests/ssl/set_ssl_cert_bundle.vtc
index 3b3c0b343a..8e145ef738 100644
--- a/reg-tests/ssl/set_ssl_cert_bundle.vtc
+++ b/reg-tests/ssl/set_ssl_cert_bundle.vtc
@@ -28,6 +28,10 @@ server s1 -repeat 9 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     .if !ssllib_name_startswith(AWS-LC)
         tune.ssl.default-dh-param 2048
     .endif
diff --git a/reg-tests/ssl/set_ssl_cert_noext.vtc b/reg-tests/ssl/set_ssl_cert_noext.vtc
index ed5fdb5c73..65773d89e0 100644
--- a/reg-tests/ssl/set_ssl_cert_noext.vtc
+++ b/reg-tests/ssl/set_ssl_cert_noext.vtc
@@ -23,6 +23,10 @@ server s1 -repeat 3 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     .if !ssllib_name_startswith(AWS-LC)
         tune.ssl.default-dh-param 2048
     .endif
diff --git a/reg-tests/ssl/set_ssl_crlfile.vtc b/reg-tests/ssl/set_ssl_crlfile.vtc
index 86cab00173..05ff673821 100644
--- a/reg-tests/ssl/set_ssl_crlfile.vtc
+++ b/reg-tests/ssl/set_ssl_crlfile.vtc
@@ -30,6 +30,10 @@ server s1 -repeat 4 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     .if !ssllib_name_startswith(AWS-LC)
         tune.ssl.default-dh-param 2048
     .endif
diff --git a/reg-tests/ssl/set_ssl_server_cert.vtc b/reg-tests/ssl/set_ssl_server_cert.vtc
index 55d8df0efa..db23e705b2 100644
--- a/reg-tests/ssl/set_ssl_server_cert.vtc
+++ b/reg-tests/ssl/set_ssl_server_cert.vtc
@@ -16,6 +16,10 @@ server s1 -repeat 4 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     .if !ssllib_name_startswith(AWS-LC)
         tune.ssl.default-dh-param 2048
     .endif
diff --git a/reg-tests/ssl/show_ssl_ocspresponse.vtc b/reg-tests/ssl/show_ssl_ocspresponse.vtc
index 08969ba2b3..47d2ec0024 100644
--- a/reg-tests/ssl/show_ssl_ocspresponse.vtc
+++ b/reg-tests/ssl/show_ssl_ocspresponse.vtc
@@ -27,6 +27,10 @@ feature ignore_unknown_macro
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     .if !ssllib_name_startswith(AWS-LC)
         tune.ssl.default-dh-param 2048
     .endif
diff --git a/reg-tests/ssl/ssl_alpn.vtc b/reg-tests/ssl/ssl_alpn.vtc
index 9d032769c8..36cbc38e7b 100644
--- a/reg-tests/ssl/ssl_alpn.vtc
+++ b/reg-tests/ssl/ssl_alpn.vtc
@@ -11,6 +11,10 @@ feature ignore_unknown_macro
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     .if !ssllib_name_startswith(AWS-LC)
         tune.ssl.default-dh-param 2048
     .endif
diff --git a/reg-tests/ssl/ssl_client_auth.vtc b/reg-tests/ssl/ssl_client_auth.vtc
index a223a9c18b..ec555651d7 100644
--- a/reg-tests/ssl/ssl_client_auth.vtc
+++ b/reg-tests/ssl/ssl_client_auth.vtc
@@ -25,6 +25,10 @@ server s1 -repeat 3 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     .if !ssllib_name_startswith(AWS-LC)
         tune.ssl.default-dh-param 2048
     .endif
diff --git a/reg-tests/ssl/ssl_client_samples.vtc b/reg-tests/ssl/ssl_client_samples.vtc
index 6b770822c9..db3589f36b 100644
--- a/reg-tests/ssl/ssl_client_samples.vtc
+++ b/reg-tests/ssl/ssl_client_samples.vtc
@@ -12,6 +12,10 @@ server s1 -repeat 3 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     .if !ssllib_name_startswith(AWS-LC)
         tune.ssl.default-dh-param 2048
     .endif
diff --git a/reg-tests/ssl/ssl_crt-list_filters.vtc b/reg-tests/ssl/ssl_crt-list_filters.vtc
index 843d85af47..a911f03955 100644
--- a/reg-tests/ssl/ssl_crt-list_filters.vtc
+++ b/reg-tests/ssl/ssl_crt-list_filters.vtc
@@ -16,6 +16,10 @@ server s1 -repeat 6 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     .if !ssllib_name_startswith(AWS-LC)
         tune.ssl.default-dh-param 2048
     .endif
diff --git a/reg-tests/ssl/ssl_curve_name.vtc b/reg-tests/ssl/ssl_curve_name.vtc
index 551679177e..68587148e6 100644
--- a/reg-tests/ssl/ssl_curve_name.vtc
+++ b/reg-tests/ssl/ssl_curve_name.vtc
@@ -11,6 +11,10 @@ server s1 -repeat 3 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     .if !ssllib_name_startswith(AWS-LC)
         tune.ssl.default-dh-param 2048
     .endif
diff --git a/reg-tests/ssl/ssl_curves.vtc b/reg-tests/ssl/ssl_curves.vtc
index 5ffd2d8bdf..da0054e7ea 100644
--- a/reg-tests/ssl/ssl_curves.vtc
+++ b/reg-tests/ssl/ssl_curves.vtc
@@ -39,6 +39,10 @@ syslog Slg_cust_fmt -level info {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     .if !ssllib_name_startswith(AWS-LC)
         tune.ssl.default-dh-param 2048
     .endif
diff --git a/reg-tests/ssl/ssl_default_server.vtc b/reg-tests/ssl/ssl_default_server.vtc
index 88a3ccbe4d..0f49b1b808 100644
--- a/reg-tests/ssl/ssl_default_server.vtc
+++ b/reg-tests/ssl/ssl_default_server.vtc
@@ -22,6 +22,10 @@ server s1 -repeat 7 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     .if !ssllib_name_startswith(AWS-LC)
         tune.ssl.default-dh-param 2048
     .endif
diff --git a/reg-tests/ssl/ssl_dh.vtc b/reg-tests/ssl/ssl_dh.vtc
index 5fe7c88aa2..b569f8a1d1 100644
--- a/reg-tests/ssl/ssl_dh.vtc
+++ b/reg-tests/ssl/ssl_dh.vtc
@@ -31,6 +31,10 @@ server s1 -repeat 8 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         stats socket "${tmpdir}/h1/stats" level admin
 
     defaults
@@ -67,9 +71,17 @@ haproxy h1 -conf {
 
 haproxy h2 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         stats socket "${tmpdir}/h2/stats" level admin
 
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         tune.ssl.default-dh-param 4096
 
     defaults
@@ -94,9 +106,17 @@ haproxy h2 -conf {
 
 haproxy h3 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         stats socket "${tmpdir}/h3/stats" level admin
 
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
         ssl-dh-param-file ${testdir}/common.4096.dh
 
     defaults
diff --git a/reg-tests/ssl/ssl_errors.vtc b/reg-tests/ssl/ssl_errors.vtc
index a3c54553c6..8025dbd96f 100644
--- a/reg-tests/ssl/ssl_errors.vtc
+++ b/reg-tests/ssl/ssl_errors.vtc
@@ -168,6 +168,10 @@ syslog Slg_bcknd_fe -level info {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     .if !ssllib_name_startswith(AWS-LC)
         tune.ssl.default-dh-param 2048
     .endif
@@ -227,7 +231,7 @@ haproxy h1 -conf {
         server wrong_ciphers2 "${tmpdir}/wrong_ciphers_ssl.sock" ssl verify none crt ${testdir}/client1.pem ca-file ${testdir}/ca-auth.crt force-tlsv12 ciphers "aECDSA" sni str(foo.com)
 .else
         server wrong_ciphers_tls13 "${tmpdir}/wrong_ciphers_tls13_ssl.sock" ssl verify none crt ${testdir}/client1.pem ca-file ${testdir}/ca-auth.crt ciphersuites "TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256" force-tlsv13 sni str(foo.com)
-.endif
+    .endif
 
 
 
@@ -293,7 +297,7 @@ haproxy h1 -conf {
     listen wrong_ciphers_tls13_ssl_lst from bknd_err_dflt
         bind "${tmpdir}/wrong_ciphers_tls13_ssl.sock" ssl crt ${testdir}/common.pem ca-file ${testdir}/ca-auth.crt verify none force-tlsv13 ciphersuites "TLS_AES_128_GCM_SHA256"
         server s1 ${s1_addr}:${s1_port}
-.endif
+    .endif
 
 } -start
 
diff --git a/reg-tests/ssl/ssl_frontend_samples.vtc b/reg-tests/ssl/ssl_frontend_samples.vtc
index 56a208bccd..118795b15b 100644
--- a/reg-tests/ssl/ssl_frontend_samples.vtc
+++ b/reg-tests/ssl/ssl_frontend_samples.vtc
@@ -11,6 +11,10 @@ server s1 -repeat 3 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     .if !ssllib_name_startswith(AWS-LC)
         tune.ssl.default-dh-param 2048
     .endif
diff --git a/reg-tests/ssl/ssl_generate_certificate.vtc b/reg-tests/ssl/ssl_generate_certificate.vtc
index ace27d877b..0bd6fbc448 100644
--- a/reg-tests/ssl/ssl_generate_certificate.vtc
+++ b/reg-tests/ssl/ssl_generate_certificate.vtc
@@ -27,6 +27,10 @@ server s1 -repeat 6 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     .if !ssllib_name_startswith(AWS-LC)
         tune.ssl.default-dh-param 2048
     .endif
diff --git a/reg-tests/ssl/ssl_reuse.vtc b/reg-tests/ssl/ssl_reuse.vtc
index d7244eeb4d..57ef5f62ce 100644
--- a/reg-tests/ssl/ssl_reuse.vtc
+++ b/reg-tests/ssl/ssl_reuse.vtc
@@ -15,6 +15,10 @@ server s1 -repeat 84 {
 
 haproxy h1 -conf {
    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
       # forced to 1 here, because there is a cached session per thread
       nbthread 1
 
diff --git a/reg-tests/ssl/ssl_server_samples.vtc b/reg-tests/ssl/ssl_server_samples.vtc
index 2841d1cc63..c8c52081bf 100644
--- a/reg-tests/ssl/ssl_server_samples.vtc
+++ b/reg-tests/ssl/ssl_server_samples.vtc
@@ -11,6 +11,10 @@ server s1 -repeat 3 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     .if !ssllib_name_startswith(AWS-LC)
         tune.ssl.default-dh-param 2048
     .endif
diff --git a/reg-tests/ssl/ssl_simple_crt-list.vtc b/reg-tests/ssl/ssl_simple_crt-list.vtc
index d70327b0b1..fa6c767b12 100644
--- a/reg-tests/ssl/ssl_simple_crt-list.vtc
+++ b/reg-tests/ssl/ssl_simple_crt-list.vtc
@@ -12,6 +12,10 @@ server s1 -repeat 4 {
 
 haproxy h1 -conf {
     global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     .if !ssllib_name_startswith(AWS-LC)
         tune.ssl.default-dh-param 2048
     .endif
diff --git a/reg-tests/ssl/wrong_ctx_storage.vtc b/reg-tests/ssl/wrong_ctx_storage.vtc
index 4275731fe6..1522e0211c 100644
--- a/reg-tests/ssl/wrong_ctx_storage.vtc
+++ b/reg-tests/ssl/wrong_ctx_storage.vtc
@@ -24,6 +24,10 @@ feature ignore_unknown_macro
 
 haproxy h1 -conf {
   global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
   .if !ssllib_name_startswith(AWS-LC)
     tune.ssl.default-dh-param 2048
   .endif
diff --git a/reg-tests/startup/automatic_maxconn.vtc b/reg-tests/startup/automatic_maxconn.vtc
index 0173916198..2b47ee166f 100644
--- a/reg-tests/startup/automatic_maxconn.vtc
+++ b/reg-tests/startup/automatic_maxconn.vtc
@@ -45,6 +45,11 @@ haproxy h3 -cli {
 # 1 SSL front but no back
 
 haproxy h4 -arg "-m 256" -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 	defaults
 		mode http
 		timeout connect 1s
@@ -64,6 +69,11 @@ haproxy h4 -cli {
 # 1 SSL back but not front
 
 haproxy h5 -arg "-m 256" -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 	defaults
 		mode http
 		timeout connect 1s
@@ -85,6 +95,11 @@ haproxy h5 -cli {
 # 1 SSL front and 1 back
 
 haproxy h6 -arg "-m 256" -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 	defaults
 		mode http
 		timeout connect 1s
diff --git a/reg-tests/startup/default_rules.vtc b/reg-tests/startup/default_rules.vtc
index 654e9cf3db..1774872db6 100644
--- a/reg-tests/startup/default_rules.vtc
+++ b/reg-tests/startup/default_rules.vtc
@@ -7,37 +7,72 @@ feature ignore_unknown_macro
 # anonymous defaults section cannot define TCP/HTTP rules
 #
 haproxy h1 -conf-BAD {} {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         http-request set-header X-Hdr 1
 }
 
 haproxy h2 -conf-BAD {} {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         http-response set-header X-Hdr 1
 }
 
 haproxy h3 -conf-BAD {} {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         http-after-request set-header X-Hdr 1
 }
 
 haproxy h4 -conf-BAD {} {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         tcp-request connection accept
 }
 
 haproxy h5 -conf-BAD {} {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         tcp-request session accept
 }
 
 haproxy h6 -conf-BAD {} {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         tcp-request inspect-delay 5s
         tcp-request content accept
 }
 
 haproxy h7 -conf-BAD {} {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         tcp-response inspect-delay 5s
         tcp-response content accept
@@ -48,6 +83,11 @@ haproxy h7 -conf-BAD {} {
 # defaults section
 #
 haproxy h8 -conf-BAD {} {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults invalid
         tcp-response inspect-delay 5s
         tcp-response content accept
@@ -61,6 +101,11 @@ haproxy h8 -conf-BAD {} {
 # section
 #
 haproxy h9 -conf-BAD {} {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults invalid
         tcp-request inspect-delay 5s
         tcp-request content accept
@@ -77,6 +122,11 @@ haproxy h9 -conf-BAD {} {
 #
 #
 haproxy h10 -conf-BAD {} {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults invalid
         tcp-request inspect-delay 5s
         tcp-request content accept
@@ -96,6 +146,11 @@ haproxy h10 -conf-BAD {} {
 # rules cannot be used to init backend sections
 #
 haproxy h11 -conf-BAD {} {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults invalid
         tcp-request connection accept
 
@@ -105,6 +160,11 @@ haproxy h11 -conf-BAD {} {
 }
 
 haproxy h12 -conf-BAD {} {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults invalid
         tcp-request session accept
 
@@ -118,6 +178,11 @@ haproxy h12 -conf-BAD {} {
 # a frontend section
 #
 haproxy h13 -conf-BAD {} {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults invalid
         tcp-response inspect-delay 5s
         tcp-response content accept
@@ -128,6 +193,11 @@ haproxy h13 -conf-BAD {} {
 }
 
 haproxy h14 -arg -V -conf-OK {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults tcp
 	timeout client 30s
 	timeout server 30s
@@ -146,6 +216,11 @@ haproxy h14 -arg -V -conf-OK {
 #
 
 haproxy h15 -conf-BAD {} {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults invalid
         mode http
         http-request set-header x-test "%[srv_conn(www)]"
@@ -155,6 +230,11 @@ haproxy h15 -conf-BAD {} {
 }
 
 haproxy h16 -conf-BAD {} {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults invalid
         mode http
         http-request track-sc0 src
@@ -166,6 +246,11 @@ haproxy h16 -conf-BAD {} {
 }
 
 haproxy h17 -arg -V -conf-OK {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults common
 	timeout client 30s
 	timeout server 30s
diff --git a/reg-tests/stats/stats-file.vtc b/reg-tests/stats/stats-file.vtc
index 8e4aaa9f34..fab008b954 100644
--- a/reg-tests/stats/stats-file.vtc
+++ b/reg-tests/stats/stats-file.vtc
@@ -5,6 +5,10 @@ feature ignore_unknown_macro
 
 haproxy h1 -conf {
 	global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 		stats-file ${testdir}/sample-stats-file
 
 	defaults
diff --git a/reg-tests/stick-table/converteers_ref_cnt_never_dec.vtc b/reg-tests/stick-table/converteers_ref_cnt_never_dec.vtc
index 9f39d826e8..b409ea0204 100644
--- a/reg-tests/stick-table/converteers_ref_cnt_never_dec.vtc
+++ b/reg-tests/stick-table/converteers_ref_cnt_never_dec.vtc
@@ -27,6 +27,11 @@ server s1 {
 
 haproxy h1 -conf {
     # Configuration file of 'h1' haproxy instance.
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode   http
         timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/stick-table/src_conn_rate.vtc b/reg-tests/stick-table/src_conn_rate.vtc
index bdf8869bee..9ec475b634 100644
--- a/reg-tests/stick-table/src_conn_rate.vtc
+++ b/reg-tests/stick-table/src_conn_rate.vtc
@@ -2,6 +2,11 @@ varnishtest "stick table: src_conn_rate"
 feature ignore_unknown_macro
 
 haproxy h0 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 	defaults
 		mode http
 		timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/stick-table/unknown_key.vtc b/reg-tests/stick-table/unknown_key.vtc
index f0307cb210..3a86963de9 100644
--- a/reg-tests/stick-table/unknown_key.vtc
+++ b/reg-tests/stick-table/unknown_key.vtc
@@ -11,6 +11,11 @@ server s0 {
 } -start
 
 haproxy h0 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
 	defaults
 		timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
 		timeout client  "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/stickiness/lb-services.vtc b/reg-tests/stickiness/lb-services.vtc
index 23c9a9afd1..a515118695 100644
--- a/reg-tests/stickiness/lb-services.vtc
+++ b/reg-tests/stickiness/lb-services.vtc
@@ -42,6 +42,11 @@ server s4 {
 } -repeat 2 -start
 
 haproxy h1 -arg "-L A" -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout server "${HAPROXY_TEST_TIMEOUT-5s}"
@@ -105,6 +110,11 @@ server s8 {
 
 
 haproxy h2 -arg "-L B" -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout server "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/stickiness/srvkey-addr.vtc b/reg-tests/stickiness/srvkey-addr.vtc
index cf9c313f5d..fdb00f9ace 100644
--- a/reg-tests/stickiness/srvkey-addr.vtc
+++ b/reg-tests/stickiness/srvkey-addr.vtc
@@ -31,6 +31,11 @@ server s2 {
 } -repeat 8 -start
 
 haproxy h1 -arg "-L A" -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout server "${HAPROXY_TEST_TIMEOUT-5s}"
@@ -72,6 +77,11 @@ haproxy h1 -arg "-L A" -conf {
 }
 
 haproxy h2 -arg "-L B" -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout server "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/stream/unique-id-from-proxy.vtc b/reg-tests/stream/unique-id-from-proxy.vtc
index fc91f257d0..9b3ffd164f 100644
--- a/reg-tests/stream/unique-id-from-proxy.vtc
+++ b/reg-tests/stream/unique-id-from-proxy.vtc
@@ -3,6 +3,11 @@ varnishtest "Check that we are able to read a unique-id from PROXYv2"
 feature ignore_unknown_macro
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/stream/unique-id.vtc b/reg-tests/stream/unique-id.vtc
index 0607b2a4fa..5b580af828 100644
--- a/reg-tests/stream/unique-id.vtc
+++ b/reg-tests/stream/unique-id.vtc
@@ -8,6 +8,11 @@ server s1 {
 } -repeat 2 -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     defaults
         mode http
         timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/tcp-rules/default_rules.vtc b/reg-tests/tcp-rules/default_rules.vtc
index 8c05f4306b..b99a20fe8c 100644
--- a/reg-tests/tcp-rules/default_rules.vtc
+++ b/reg-tests/tcp-rules/default_rules.vtc
@@ -11,6 +11,11 @@ server s1 {
 }  -start
 
 haproxy h1 -conf {
+    global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
   defaults common
       mode http
       timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
diff --git a/reg-tests/webstats/webstats-scope-and-post-change.vtc b/reg-tests/webstats/webstats-scope-and-post-change.vtc
index 7830ae5b45..604abff4d1 100644
--- a/reg-tests/webstats/webstats-scope-and-post-change.vtc
+++ b/reg-tests/webstats/webstats-scope-and-post-change.vtc
@@ -7,6 +7,10 @@ server s1 {
 
 haproxy h1 -conf {
   global
+    .if feature(THREAD)
+        thread-groups 1
+    .endif
+
     # WT: limit false-positives causing "HTTP header incomplete" due to
     # idle server connections being randomly used and randomly expiring
     # under us.