From: Willy Tarreau <w@1wt.eu>
Date: Sun, 28 Oct 2018 12:44:36 +0000 (+0100)
Subject: MINOR: stream: don't prune variables if the list is empty
X-Git-Tag: v1.9-dev5~35
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=cda7f3f5;p=thirdparty%2Fhaproxy.git

MINOR: stream: don't prune variables if the list is empty

The vars_prune() and vars_init() functions involve locking while most of
the time there is no variable at all in streams nor sessions. Let's check
for emptiness before calling these functions. Simply doing this has
increased the multithreaded performance from 1.5 to 5% depending on the
workload.
---

diff --git a/src/proto_http.c b/src/proto_http.c
index 48cb383a0d..39900deac1 100644
--- a/src/proto_http.c
+++ b/src/proto_http.c
@@ -7566,8 +7566,10 @@ void http_end_txn(struct stream *s)
 		memset(s->res_cap, 0, fe->nb_rsp_cap * sizeof(void *));
 	}
 
-	vars_prune(&s->vars_txn, s->sess, s);
-	vars_prune(&s->vars_reqres, s->sess, s);
+	if (!LIST_ISEMPTY(&s->vars_txn.head))
+		vars_prune(&s->vars_txn, s->sess, s);
+	if (!LIST_ISEMPTY(&s->vars_reqres.head))
+		vars_prune(&s->vars_reqres, s->sess, s);
 }
 
 /* to be used at the end of a transaction to prepare a new one */
diff --git a/src/stream.c b/src/stream.c
index ad1ccbee40..d27dae3a22 100644
--- a/src/stream.c
+++ b/src/stream.c
@@ -376,8 +376,10 @@ static void stream_free(struct stream *s)
 	}
 
 	/* Cleanup all variable contexts. */
-	vars_prune(&s->vars_txn, s->sess, s);
-	vars_prune(&s->vars_reqres, s->sess, s);
+	if (!LIST_ISEMPTY(&s->vars_txn.head))
+		vars_prune(&s->vars_txn, s->sess, s);
+	if (!LIST_ISEMPTY(&s->vars_reqres.head))
+		vars_prune(&s->vars_reqres, s->sess, s);
 
 	stream_store_counters(s);
 
@@ -2258,8 +2260,10 @@ redo:
 
 		/* prune the request variables and swap to the response variables. */
 		if (s->vars_reqres.scope != SCOPE_RES) {
-			vars_prune(&s->vars_reqres, s->sess, s);
-			vars_init(&s->vars_reqres, SCOPE_RES);
+			if (!LIST_ISEMPTY(&s->vars_reqres.head)) {
+				vars_prune(&s->vars_reqres, s->sess, s);
+				vars_init(&s->vars_reqres, SCOPE_RES);
+			}
 		}
 
 		do {