max #process for nginx sync to php-fpm

Question

Apart from memory and cpu limitations, I'd like to keep in mind another number for the nginx and php-fpm setup.

If there is process.max set in /etc/php5/fpm/php-fpm.conf, the max number of php process ready for serving is limited.

However, nginx never knows about this limit and tries to find and get served by another php-fpm process.

How to limit nginx to request the same max at the same moment? (independent from cpu/ram which is discussed and explained in lots of other posts)

Changaco · Accepted Answer · 2013-09-07 18:56:39Z

0

nginx doesn't spawn the php-fpm workers, it doesn't need to know about the limit.

answered Sep 7, 2013 at 18:56

Changaco

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that's the conflict, isn't it? nginx will try to get even more php process' though the max number is limited and will never be more because of php-fpm's config. i wonder how this could be considered in order to have nginx not ending up in errors 502 if the number is exceeded.
– ledy
Sep 7, 2013 at 19:13
Having 2 workers doesn't mean that if you get 3 simultaneous requests the last one will 502, it just gets queued until it can be handled.
– Changaco
Sep 7, 2013 at 19:28
The queue seems to fail or break. Whenever the request can't be served quickly enough, nginx error recv() failed (104: Connection reset by peer) while reading response header from upstream, client: and WARNING: The maximum number of processes has been reached. suggesting to consider max values. but that's not wanted. instead, i want it to wait, not to request even more at the same time or http deny with err code 502, also fail :-(
– ledy
Sep 7, 2013 at 21:35
The problem is not in nginx or its configuration. The error message indicates that php-fpm closed the connection, you should try to find out why.
– Changaco
Sep 8, 2013 at 8:29
though php-fpm config is set to log level=notice, it only tells about WARNING: [pool www] seems busy (you may need to increase pm.start_servers, or pm.min/max_spare_servers). it reached maximum, so i'd expect it to use a queue - not disconnect nginx.
– ledy
Sep 8, 2013 at 8:59

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