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[2019-05-31 12:11 UTC] stefan dot djordjevic at humanity dot com
Description:
------------
Hi,
We got some strange behaviour which seems related to shared lockfile stored on a default path (/tmp/.ZendSem.04tkPY)
Randomly our Apache server with forked workers enter in some strange "loop", which slows them down and brings our load and number of apache workers to max.
I mange to strace them and what I see is:
cntl(10, F_SETLKW, {l_type=F_WRLCK, l_whence=SEEK_SET, l_start=0, l_len=1}) = 0
fcntl(10, F_SETLK, {l_type=F_UNLCK, l_whence=SEEK_SET, l_start=0, l_len=1}) = 0
fcntl(10, F_SETLKW, {l_type=F_WRLCK, l_whence=SEEK_SET, l_start=0, l_len=1}) = 0
fcntl(10, F_SETLK, {l_type=F_UNLCK, l_whence=SEEK_SET, l_start=0, l_len=1}) = 0
fcntl(10, F_SETLKW, {l_type=F_WRLCK, l_whence=SEEK_SET, l_start=0, l_len=1}) = 0
fcntl(10, F_SETLK, {l_type=F_UNLCK, l_whence=SEEK_SET, l_start=0, l_len=1}) = 0
fcntl(10, F_SETLKW, {l_type=F_WRLCK, l_whence=SEEK_SET, l_start=0, l_len=1}) = 0
fcntl(10, F_SETLK, {l_type=F_UNLCK, l_whence=SEEK_SET, l_start=0, l_len=1}) = 0
.
.
At one point in time it just passed this "condition" and execute, finish request.
File Descriptor is actually pointing to opcode lock files:
ls -l /proc/30174/fd/10
lrwx------ 1 root root 64 May 30 13:35 /proc/30174/fd/10 -> /tmp/.ZendSem.04tkPY (deleted)
As this condition happens pretty randomly, it's hard to identify real cause of this, but from what I see is that it entering some kind of loop, or race condition with locking - unlocking pattern.
I am trying to figure out how we get to this condition, as there are many "variables" included in our new setup (docker containers etc.) I am wondering if you guys have any clue if this can be triggered by some kind of bug in Zend opcode cache-ing mechanism or similar ?
Thanks.
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Last updated: Sat Sep 30 20:01:25 2023 UTC |
Hi, I think I just encountered the same error. We have customers complaining that they can't login to their WordPress websites. After some debugging, I found out that it's caused by a PHP process with a 100% CPU usage on wp-admin/load-styles.php, lopping over two system calls : fcntl(3, F_SETLK, {l_type=F_UNLCK, l_whence=SEEK_SET, l_start=0, l_len=1}) = 0 fcntl(3, F_SETLKW, {l_type=F_WRLCK, l_whence=SEEK_SET, l_start=0, l_len=1}) = 0 The file descriptor seems deleted too : [root@ruby fd]# ls -lha /proc/26052/fd/3 lrwx------ 1 xxxx xxxx 64 2 juil. 11:30 3 -> /tmp/.ZendSem.Tj7ZFx (deleted) I think I only have this problem with PHP 8.1. If I change the PHP version to 8.2 or 8.0, it seems to fix the problem (at least, I don't have the customer complaining about this issue anymore) The current version of PHP I'm using is : [root@ruby fd]# /opt/alt/php81/usr/bin/php -v PHP 8.1.20 (cli) (built: Jun 14 2023 08:52:43) (NTS) Copyright (c) The PHP Group Zend Engine v4.1.20, Copyright (c) Zend Technologies I'm using the litespeed (lsphp) : [root@ruby fd]# /opt/alt/php81/usr/bin/lsphp -v PHP 8.1.20 (litespeed) (built: Jun 14 2023 08:56:47) Copyright (c) 1997-2016 The PHP Group Zend Engine v4.1.20, Copyright (c) Zend Technologies I think it's related to opcache because if I stay on PHP 8.1 AND disable opcache, it also seems to fix the problem. I'm not familiar with PHP internals, it seems to be a locking error of some kind. It also could be a problem related to CloudLinux and their cageFS system because when I do a cagefsctl --remount {user} it seems to temporarily fix the problem for a few minutes. I'm not 100% sure it's a PHP bug. Thanks.