Jgutie11 at 00:54, 26 November 2020

2020-11-26T00:54:26Z

← Older revision		Revision as of 00:54, 26 November 2020
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	max ops per semop call = 32		max ops per semop call = 32
	semaphore max value = 32767		semaphore max value = 32767

			[[Category:Sysadmin]]

Jgutie11: Created page with " == Introduction == Httpd failing due to not having enough space to make semaphore/mutex locks. When doing systemctl restart httpd, semaphores are not destroyed properly and..."

2020-11-26T00:52:13Z

Created page with " == Introduction == Httpd failing due to not having enough space to make semaphore/mutex locks. When doing systemctl restart httpd, semaphores are not destroyed properly and..."

New page

== Introduction ==
Httpd failing due to not having enough space to make semaphore/mutex locks.

When doing systemctl restart httpd, semaphores are not destroyed properly and the locks are accumulated until it reaches the max capacity.

== Lock Error ==
Check the error_log in /etc/httpd/logs/error_log. If this error exists then follow the solution:

'''[Wed Nov 25 12:27:57.636689 2020] [core:emerg] [pid 24252] (28)No space left on device: AH00023: Couldn't create the mpm-accept mutex'''

== Solution ==
Do the following:
* vim /usr/lib/systemd/system/httpd.service
add this line before ExecStart: '''ExecStartPre=/bin/sh -c "for i in `ipcs -s | awk '/httpd/ {print $2}'`; do (ipcrm -s $i); done"''' //clear httpd semaphores each restart
comment this line: '''KillSignal=SIGKILL''' //This does not gracefully destroy locks
save
ipcs -s | awk -v user=apache '$3==user {system("ipcrm -s "$2)}' //clear previous httpd locks
systemctl restart httpd
=== Double Check ===
Do the following commands:
ipcs -s | grep apache | wc -l //displays number of locks used by apache
systemctl restart httpd
ipcs -s | grep apache | wc -l //again to see if locks increased unnecessarily
If the locks amount stay the same you are good to go.

== Increase Semaphore Locks capacity ===
vim /etc/sysctl.d/99-sysctl.conf
add this line: '''kernel.sem = 250 256000 32 1024'''
save
sysctl -p //reload rules

Check if rules applied with:
ipcs -ls
------ Semaphore Limits --------
max number of arrays = 1024
max semaphores per array = 250
max semaphores system wide = 256000
max ops per semop call = 32
semaphore max value = 32767

HTTPD Semaphore/Mutex Lock Problem - Revision history

Jgutie11 at 00:54, 26 November 2020

Jgutie11: Created page with " == Introduction == Httpd failing due to not having enough space to make semaphore/mutex locks. When doing systemctl restart httpd, semaphores are not destroyed properly and..."