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Posted to cvs@httpd.apache.org by rp...@apache.org on 2008/10/08 15:32:08 UTC
svn commit: r702867 - in /httpd/httpd/trunk: CHANGES
server/mpm/worker/fdqueue.c
Author: rpluem
Date: Wed Oct 8 06:32:07 2008
New Revision: 702867
URL: http://svn.apache.org/viewvc?rev=702867&view=rev
Log:
* Recheck again if idle workers are still available when we are signaled that
they are. This is needed since it can happen that we are signaled by a
worker thread that went idle but received a context switch before it could
tell us. If it does signal us later once it is on CPU again there might be
no idle worker left. See
https://issues.apache.org/bugzilla/show_bug.cgi?id=45605#c4
PR: 45605
Submitted by: Denis Ustimenko <denusk gmail.com>
Reviewed by: rpluem
Modified:
httpd/httpd/trunk/CHANGES
httpd/httpd/trunk/server/mpm/worker/fdqueue.c
Modified: httpd/httpd/trunk/CHANGES
URL: http://svn.apache.org/viewvc/httpd/httpd/trunk/CHANGES?rev=702867&r1=702866&r2=702867&view=diff
==============================================================================
--- httpd/httpd/trunk/CHANGES [utf-8] (original)
+++ httpd/httpd/trunk/CHANGES [utf-8] Wed Oct 8 06:32:07 2008
@@ -2,6 +2,10 @@
Changes with Apache 2.3.0
[ When backported to 2.2.x, remove entry from this file ]
+ *) Worker MPM: Crosscheck that idle workers are still available before using
+ them and thus preventing an overflow of the worker queue which causes
+ a SegFault. PR 45605 [Denis Ustimenko <denusk gmail.com>]
+
*) mod_proxy_ajp: Fix wrongly formatted requests where client
sets Content-Length header, but doesn't provide a body.
Servlet container always expects that next packet is
Modified: httpd/httpd/trunk/server/mpm/worker/fdqueue.c
URL: http://svn.apache.org/viewvc/httpd/httpd/trunk/server/mpm/worker/fdqueue.c?rev=702867&r1=702866&r2=702867&view=diff
==============================================================================
--- httpd/httpd/trunk/server/mpm/worker/fdqueue.c (original)
+++ httpd/httpd/trunk/server/mpm/worker/fdqueue.c Wed Oct 8 06:32:07 2008
@@ -155,7 +155,15 @@
* region, one of two things may have happened:
* - If the idle worker count is still zero, the
* workers are all still busy, so it's safe to
- * block on a condition variable.
+ * block on a condition variable, BUT
+ * we need to check for idle worker count again
+ * when we are signaled since it can happen that
+ * we are signaled by a worker thread that went idle
+ * but received a context switch before it could
+ * tell us. If it does signal us later once it is on
+ * CPU again there might be no idle worker left.
+ * See
+ * https://issues.apache.org/bugzilla/show_bug.cgi?id=45605#c4
* - If the idle worker count is nonzero, then a
* worker has become idle since the first check
* of queue_info->idlers above. It's possible
@@ -166,7 +174,7 @@
* now nonzero, it's safe for this function to
* return immediately.
*/
- if (queue_info->idlers == 0) {
+ while (queue_info->idlers == 0) {
rv = apr_thread_cond_wait(queue_info->wait_for_idler,
queue_info->idlers_mutex);
if (rv != APR_SUCCESS) {