Random 503 error

[2cfg]

Hello.
We use Cloudlinux with ISP Manager 5 Bussines (shared hosting control panel) and Apache in prefork mode with LSAPI.
We get random 503 errors on many sites (about 100).
Currently, Cloudlinux support can't resolve this problem.

We see errors in error log:

[Fri Jun 26 16:43:44.466318 2020] [lsapi:error] [pid 94611] [client 127.0.0.1:33852] [host wp.2cfg.su] Error on sending request(HEAD /wp-cron.php HTTP/1.1); uri(/wp-cron.php) content-length(0): ReceiveAckHdr: nothing to read from backend (LVE ID 8699), check http://docs.cloudlinux.com/mod_lsapi_troubleshooting.html

But these recommendations have no effect.

We follow instructions on this page https://www.litespeedtech.com/support/wiki/doku.php/litespeed_wiki:php:503-errors
and got a process error trace log

-- skip --
60730 16:43:44.462141 lstat("/var", {st_mode=S_IFDIR|0755, st_size=4096, ...}) = 0 <0.000013>
60730 16:43:44.462213 open("/var/www/roman/data/www/wp.2cfg.su/wp-includes/author-template.php", O_RDONLY) = 6 <0.000022>
60730 16:43:44.462287 fstat(6, {st_mode=S_IFREG|0644, st_size=16650, ...}) = 0 <0.000012>
60730 16:43:44.462352 read(6, "<?php\n/**\n * Author Template fun"..., 16650) = 16650 <0.000019>
60730 16:43:44.462423 --- SIGHUP {si_signo=SIGHUP, si_code=SI_USER, si_pid=59832, si_uid=0} ---
60730 16:43:44.462481 rt_sigaction(SIGHUP, NULL, {sa_handler=0x64e480, sa_mask=~[ILL TRAP ABRT BUS FPE KILL SEGV CONT STOP TSTP TTIN TTOU SYS RTMIN RT_1], sa_flags=SA_RESTORER|SA_SIGINFO, sa_restorer=0x7fc6a8e8c400}, 8) = 0 <0.000012>
60730 16:43:44.462572 rt_sigaction(SIGHUP, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=SA_RESTORER|SA_SIGINFO, sa_restorer=0x7fc6a8e8c400}, NULL, 8) = 0 <0.000013>
60730 16:43:44.462636 rt_sigprocmask(SIG_UNBLOCK, [HUP], NULL, 8) = 0 <0.000013>
60730 16:43:44.462709 kill(60730, SIGHUP) = 0 <0.000014>
60730 16:43:44.462767 --- SIGHUP {si_signo=SIGHUP, si_code=SI_USER, si_pid=60730, si_uid=8699} ---
60730 16:43:44.466309 +++ killed by SIGHUP +++

-- skip --
74758 16:47:10.640492 open("/var/www/roman/data/www/wp.2cfg.su/wp-includes/version.php", O_RDONLY) = 6 <0.000012>
74758 16:47:10.640538 fstat(6, {st_mode=S_IFREG|0644, st_size=759, ...}) = 0 <0.000007>
74758 16:47:10.640579 read(6, "<?php\n/**\n * WordPress Version\n "..., 759) = 759 <0.000010>
74758 16:47:10.640663 close(6)          = 0 <0.000009>
74758 16:47:10.641407 --- SIGHUP {si_signo=SIGHUP, si_code=SI_USER, si_pid=72487, si_uid=0} ---
74758 16:47:10.641446 rt_sigaction(SIGHUP, NULL, {sa_handler=0x64e480, sa_mask=~[ILL TRAP ABRT BUS FPE KILL SEGV CONT STOP TSTP TTIN TTOU SYS RTMIN RT_1], sa_flags=SA_RESTORER|SA_SIGINFO, sa_restorer=0x7f58adea4400}, 8) = 0 <0.000008>
74758 16:47:10.641497 rt_sigaction(SIGHUP, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=SA_RESTORER|SA_SIGINFO, sa_restorer=0x7f58adea4400}, NULL, 8) = 0 <0.000008>
74758 16:47:10.641536 rt_sigprocmask(SIG_UNBLOCK, [HUP], NULL, 8) = 0 <0.000007>
74758 16:47:10.641579 kill(74758, SIGHUP) = 0 <0.000009>
74758 16:47:10.641614 --- SIGHUP {si_signo=SIGHUP, si_code=SI_USER, si_pid=74758, si_uid=8699} ---
74758 16:47:10.644985 +++ killed by SIGHUP +++

What we can do to resolve this problem?

 

[Pong]

503 errors are PHP crash error, nothing to do with web server. It is out of our support scope. You just need to try the tips from the wiki. If there is core file from php, log a bug report to PHP developer if you would like to.

 

[2cfg]

503 errors are PHP crash error, nothing to do with web server. It is out of our support scope. You just need to try the tips from the wiki. If there is core file from php, log a bug report to PHP developer if you would like to.

Sorry, we found the reason for the 503 error and it is not in the php code. Because errors on many hosting sites.

SIGHUP {si_signo=SIGHUP, si_code=SI_USER, si_pid=74758, si_uid=8699}

The si_pid belongs to cagefsctl, which is part of CloudLinux. It, in turn, is called up every minute by the ispmgrnode process. About 25 php processes are killed every minute, regardless of the set tariff limits, which leads to 503 errors.