Issue PHP 7 FPM regularly unresponsive / 503

[Connector1]

Hi everyone,

we have recently upgraded one of our servers to Plesk 17 with PHP 7 (provided by OS) and PHP-FPM. While testing everything ran smoothly (as always) but running live we are fighting against regular crashes of PHP-FPM + 503 results from Apache.

I've searched the internet and this forum up and down and can tell you the following:

* Although we have regular "ERROR: unable to read what child say: Bad file descriptor (9)" errors, they don't always cause the crash. Most of the times this error appears everything runs smoothly

* When the crash happens, there is either no error or the one above in the PHP-FPM-Log.

* The vhosts can't reach the socket as soon as the crash happened, which looks like this in their logs:
"(111)Connection refused: AH02454: FCGI: attempt to connect to Unix domain socket /var/www/vhosts/system/[DOMAIN]/php-fpm.sock (*) failed

We've tried raising pm.max_children but that doesn't really seem to make a difference. Also, there's no messages about max_children being reached in any of the vhosts. There was when it was set to 5 but not anymore after raising it. The crashes keep happening, though.

Is there anything else I can check for? Is there something specific that might happen in the code of our websites that could lead to this?

Thanks for any input!

 

[themew]

Recently had a similar issue with PHP-FPM and odd 503 errors as you describe it. This worked for me:

Websites hosted in Plesk and served by PHP-FPM are unavailable or load slow: "server reached max_children setting" or "Bad file descriptor (9)"

 

[Connector1]

Thank you for your reply. For us, max_children doesn't seem to be the problem. They are never reached and we already tried increasing them.

What I noticed: This always happens the first minutes (up to ~20) after a restart / reload of php-fpm. If it doesn't crash then, it won't later.