SmartOS: Why PHP-FPM writes tons of /dev/poll warnings into log

Written by Claudio Kuenzler - 0 comments

Published on June 19th 2013 - Listed in SmartOS Unix Solaris PHP

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Over the past few hours I've been trying to find the cause for the following log entries on a SmartOS running PHP-FPM:

tail /var/log/php-fpm.log
[19-Jun-2013 17:12:07] WARNING:  /dev/poll: ioctl() returns 22
[19-Jun-2013 17:12:07] WARNING:  /dev/poll: ioctl() returns 22
[19-Jun-2013 17:12:07] WARNING:  /dev/poll: ioctl() returns 22
[19-Jun-2013 17:12:07] WARNING:  /dev/poll: ioctl() returns 22
[19-Jun-2013 17:12:07] WARNING:  /dev/poll: ioctl() returns 22
[19-Jun-2013 17:12:07] WARNING:  /dev/poll: ioctl() returns 22
[...]

SmartOS version: 5.11 joyent_20120614T184600Z i86pc i386 i86pc Solaris
PHP-FPM version: php53-fpm-5.3.10

These entries were written up to 52'000 times per second (!!!!!).

At the begin I thought a mal-programmed website was the cause so I started to disable one fpm config after another. And suddenly the entries were gone! I thought I found the responsible web-host and re-activated all php-fpm configs again. As soon as I did that, the log entries appeared again. Over quite some time I tried to manually find which webs (obviously there must be several bad customer hostings... at least that's what I thought) are causing the issue.

...Until a strange idea hit me. What if this depends on the number of php-fpm configs in /opt/local/etc/fpm.d/? I didn't get any errors when I moved most of them to a temporary folder, so that would explain it...

So I re-activated all configs and started to move away one after another (again - but this time with another goal). After each move I restarted the PHP SMF service to see if the entries stopped.
I hit the magic number 35 after some time. As soon as there were no more than 35 fpm config files, the mass logging of these warnings stopped.

Summary: SmartOS PHP-FPM can only handle up to 35 php-fpm configs in /opt/local/etc/fpm.d/. At least so it seems after my tests.

Looks like the madness is always looking for me...

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