mpm_event, mpm_worker: Fix computation of MinSpareThreads' lower bound

according the number of listeners buckets.

We want the number of children processes to be a multiple of the number of
buckets so to optimally accept connections (the system will distribute them
accross all the buckets/listeners anyway, thus children must follow).

For MinSpareThreads, this means that we need neither more nor less than one
thread above 'threads_per_child * (num_buckets - 1)' to achieve this, since
each created child adds threads_per_child workers.

Actually, given that perform_idle_server_maintenance() is called per bucket,
and hence checks 'threads_per_child / num_buckets' for one bucket, let's lower
bound MinSpareThreads to 'threads_per_child * (num_buckets - 1) + num_buckets'.

Previously we used 'threads_per_child * num_buckets' which caused one spurious
child to be created from the very first busy worker thread of each newly added
child.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1737447 13f79535-47bb-0310-9956-ffa450edef68

diff --git a/CHANGES b/CHANGES
index 5f93055e993c9968c8851fba179b3c80e6f0d822..480941c61abb9bd9c12cdd09ae07cac9610ced0c 100644 (file)
--- a/CHANGES
+++ b/CHANGES
@@ -1,6 +1,9 @@
                                                          -*- coding: utf-8 -*-
 Changes with Apache 2.5.0
 
+  *) mpm_event, mpm_worker: Fix computation of MinSpareThreads' lower bound
+     according the number of listeners buckets.  [Yann Ylavic]
+
   *) mod_proxy_http2: using HTTP/2 flow control for backend streams by 
      observing data actually send out on the frontend h2 connection. 
      [Stefan Eissing]

diff --git a/server/mpm/event/event.c b/server/mpm/event/event.c
index 6648331661d4583ffa4fbf597efd73a3bec90e50..93760606632d1d7105f43555a99b12b77a7b9a5b 100644 (file)
--- a/server/mpm/event/event.c
+++ b/server/mpm/event/event.c
@@ -3090,8 +3090,8 @@ static int event_run(apr_pool_t * _pconf, apr_pool_t * plog, server_rec * s)
         ap_daemons_limit = num_buckets;
     if (ap_daemons_to_start < num_buckets)
         ap_daemons_to_start = num_buckets;
-    if (min_spare_threads < threads_per_child * num_buckets)
-        min_spare_threads = threads_per_child * num_buckets;
+    if (min_spare_threads < threads_per_child * (num_buckets - 1) + num_buckets)
+        min_spare_threads = threads_per_child * (num_buckets - 1) + num_buckets;
     if (max_spare_threads < min_spare_threads + threads_per_child * num_buckets)
         max_spare_threads = min_spare_threads + threads_per_child * num_buckets;
 

diff --git a/server/mpm/worker/worker.c b/server/mpm/worker/worker.c
index 5cb516f9c22c2e47d2e32ec92844c9a00193f2b5..dc61adce05ded8eaf580073a8cba682fa706962e 100644 (file)
--- a/server/mpm/worker/worker.c
+++ b/server/mpm/worker/worker.c
@@ -1833,8 +1833,8 @@ static int worker_run(apr_pool_t *_pconf, apr_pool_t *plog, server_rec *s)
         ap_daemons_limit = num_buckets;
     if (ap_daemons_to_start < num_buckets)
         ap_daemons_to_start = num_buckets;
-    if (min_spare_threads < threads_per_child * num_buckets)
-        min_spare_threads = threads_per_child * num_buckets;
+    if (min_spare_threads < threads_per_child * (num_buckets - 1) + num_buckets)
+        min_spare_threads = threads_per_child * (num_buckets - 1) + num_buckets;
     if (max_spare_threads < min_spare_threads + threads_per_child * num_buckets)
         max_spare_threads = min_spare_threads + threads_per_child * num_buckets;