On 19.07.2012 23:31, [email protected] wrote:
Author: trawick
Date: Thu Jul 19 21:31:52 2012
New Revision: 1363557
URL: http://svn.apache.org/viewvc?rev=1363557&view=rev
Log:
mpm_event, mpm_worker: Remain active amidst prevalent child process
resource shortages.
This is a somewhat different direction than r168182 ("transient thread
creation errors shouldn't take down the whole server").
r168182: If APEXIT_CHILDSICK is received and there aren't any
active children at the time, exit.
Now: If APEXIT_CHILDSICK is received and we never successfully
initialized a child, exit.
The issue seen with the r168182 handling is that it is rather easy
to be left with no active child processes (which causes the server
to exit completely) during a resource shortage that lasts for some
measurable period of time, as contrasted with a resource shortage
that results in only a handful of allocation failures.
Now the server will remain active, though as long as the resource
shortage exists children may continually fail and the parent will
try once per second to create a replacement. The existing logic
to reduce the spawn rate after such errors will prevent the
parent from trying to create children more rapidly.
Modified:
httpd/httpd/trunk/CHANGES
httpd/httpd/trunk/docs/log-message-tags/next-number
httpd/httpd/trunk/server/mpm/event/event.c
httpd/httpd/trunk/server/mpm/worker/worker.c
Modified: httpd/httpd/trunk/CHANGES
URL:
http://svn.apache.org/viewvc/httpd/httpd/trunk/CHANGES?rev=1363557&r1=1363556&r2=1363557&view=diff
==============================================================================
--- httpd/httpd/trunk/CHANGES [utf-8] (original)
+++ httpd/httpd/trunk/CHANGES [utf-8] Thu Jul 19 21:31:52 2012
@@ -1,6 +1,9 @@
-*- coding: utf-8 -*-
Changes with Apache 2.5.0
+ *) mpm_event, mpm_worker: Remain active amidst prevalent child process
+ resource shortages. [Jeff Trawick]
+
*) mpm_event, mpm_worker: Fix cases where the spawn rate wasn't reduced
after child process resource shortages. [Jeff Trawick]
Modified: httpd/httpd/trunk/docs/log-message-tags/next-number
URL:
http://svn.apache.org/viewvc/httpd/httpd/trunk/docs/log-message-tags/next-number?rev=1363557&r1=1363556&r2=1363557&view=diff
==============================================================================
--- httpd/httpd/trunk/docs/log-message-tags/next-number (original)
+++ httpd/httpd/trunk/docs/log-message-tags/next-number Thu Jul 19 21:31:52 2012
@@ -1 +1 @@
-2324
+2326
Modified: httpd/httpd/trunk/server/mpm/event/event.c
URL:
http://svn.apache.org/viewvc/httpd/httpd/trunk/server/mpm/event/event.c?rev=1363557&r1=1363556&r2=1363557&view=diff
==============================================================================
--- httpd/httpd/trunk/server/mpm/event/event.c (original)
+++ httpd/httpd/trunk/server/mpm/event/event.c Thu Jul 19 21:31:52 2012
@@ -183,6 +183,7 @@ static apr_uint32_t lingering_count = 0;
static apr_uint32_t suspended_count = 0; /* Number of suspended
connections */
static apr_uint32_t clogged_count = 0; /* Number of threads processing
ssl conns */
static int resource_shortage = 0;
+static int had_healthy_child = 0;
static fd_queue_t *worker_queue;
static fd_queue_info_t *worker_queue_info;
static int mpm_state = AP_MPMQ_STARTING;
@@ -2403,6 +2404,7 @@ static void perform_idle_server_maintena
int any_dying_threads = 0;
int any_dead_threads = 0;
int all_dead_threads = 1;
+ int child_threads_active = 0;
if (i >= retained->max_daemons_limit
&& totally_free_length == retained->idle_spawn_rate)
@@ -2438,6 +2440,7 @@ static void perform_idle_server_maintena
}
if (status >= SERVER_READY && status < SERVER_GRACEFUL) {
++active_thread_count;
+ ++child_threads_active;
Couldn't we now simplify by adding child_threads_active to
active_thread_count outside the loop instead of incrementing
active_thread_count for each thread?
}
}
}
@@ -2464,6 +2467,9 @@ static void perform_idle_server_maintena
}
++free_length;
}
+ else if (child_threads_active == threads_per_child) {
+ had_healthy_child = 1;
+ }
As I understand it had_healthy_child is never reset. So when we do an
"apachectl restart" (or graceful) the children started before that event
still count. I'd say after a restart the condition should be reset,
because often the config will have changed.
...
The same comments apply to the worker MPM patch.
Regards,
Rainer
