php fpm seems busy fixed warning and max children reached to handle max connections / requests

Table of Contents

php fpm seems busy what that means

php fpm child process contains some memory ex: 128M (prescribe in php memory limit in php.ini)

by default there are 5 max children process to handle the connections from server to mysql.

128*5=640MB (max possible hold) if average 40MB (40*50=200MB)

use max or average memory to determine max php -fpm child processes.

php fpm seems busy appears when yu are using dynamic method for php-fpm processes. that means php-fpm max spare servers reached to not max children (if max children reaches php-fpm ignores connections. if php fpm seems busy or max spare servers reaches it will respawn new processes until the limit pm.max_children reaches.

28-Feb-2022 08:13:48] WARNING: [pool www] seems busy (you may need to increase pm.start_servers, or pm.min/max_spare_servers), spawning 32 children, there are 0 idle, and 109 total children
[01-Mar-2022 14:04:07] WARNING: [pool www] seems busy (you may need to increase pm.start_servers, or pm.min/max_spare_servers), spawning 8 children, there are 5 idle, and 57 total children

pm.max_children = 170, pm.start_servers = 12, pm.min_spare_servers = 6, pm.max_spare_servers = 30 (to fee this we use), pm.max_requests = 3000

more at php fpm pool settings

php fpm config for 1000 concurrent users

php-fpm terminating exiting bye-bye means

its restarting due to reaching the max process

The Problem: Php fpm process restarting when the pool is busy all connections are closing and again staring.

WARNING: [pool www] seems busy (you may need to increase pm.start_servers, or pm.min/max_spare_servers), spawning 8 children, there are 6 idle, and 21 total children

[28-Jul-2021 06:18:45] NOTICE: fpm is running, pid 438622

[28-Jul-2021 06:18:45] NOTICE: ready to handle connections

[28-Jul-2021 06:18:45] NOTICE: systemd monitor interval set to 10000ms

[29-Jul-2021 13:04:39] WARNING: [pool www] seems busy (you may need to increase pm.start_servers, or pm.min/max_spare_servers), spawning 8 children, there are 6 idle, and 21 total children

[30-Jul-2021 16:28:54] NOTICE: Terminating …

[30-Jul-2021 16:28:54] NOTICE: exiting, bye-bye!

[30-Jul-2021 16:28:54] NOTICE: fpm is running, pid 666189

why terminating the process

error vs warning busy

error server reached pm max children setting 5 consider raising it

pm.max_children = 5 fpm cannot go avove this limit either it dynamic or OnDemand or static pool.

Default

pm = dynamic

pm.max_children = 5 (128*5=640mb or less memory)

pm.start_servers = 2

pm.min_spare_servers = 1

pm.max_spare_servers = 3

5 process can handles (concurrent) confections simultaneously.

each child process has handle connection / request just like apache connection limit

Note: mysql will die if it reaches default max confections 151 consider reading mysql max onnection limit.

Beware of increasing php fpm child process

idle processes	32
active processes	2
total processes	34
max active processes	27

pm.max_children = 250
pm.start_servers = 12
pm.min_spare_servers = 12
pm.max_spare_servers = 150 (so there 32 idles process eating memory without any connection /request)

no more than spare servers than the limit.

Php max memory limit set in php.ini is the maximum memory limit for each process.

php fpm seems busy solution: just a warning

increase max spare servers & also max children

pm.max_requests = 500

(process kills after 500 rearrests so free)

or use static method

or on demand

Problem 2 serious: php fpm reached max children

WARNING: [pool nginx] server reached pm.max_children setting (180), consider raising it.

server reached pm.max_children setting (5) consider raising it docker

Solution: for php fpm pm max children reached

Increase max children limit. but consider 50MB for each children based upon max php memory limi9t and average memory usage.

php fpm configuration file: /etc/php/7.4/fpm/pool.d/

50*100=5000MB or 5GB Memory requires in extreme cases other wise it will crach.

config test for php -fpm configuration syntax errors

php-fpm7.4 -t

[03-Aug-2021 11:08:22] NOTICE: configuration file /etc/php/7.4/fpm/php-fpm.conf test is successful

reload php fpm

sudo systemctl reload php-fpm

sometimes restart requires

nginx php-fpm child exited with code 0

when pm max requests sets low..

pm.max_requests = 500

[pool www] child 696424 exited with code 0 after 49436.410120 seconds from start

before that pm.max_requests = 5000

no process respawned.

Php fpm and and nginx keep alive (for upstream servers)

Php fpm. restarting after pool busy

keepalive connection between nginx and php fpm

keepalive_requests option of your upstream to the same number as your php-fpm’s pm.max_requests,

pm.max_requests = 5000;

readv() failed (104: Connection reset by peer) while reading upstream and recv() failed (104: Connection reset by peer) while reading response header from upstream

Also check tuning nginx for max performance

FAQS on php fpm server busy

php-fpm exiting bye-bye causes

because php-fpm perhaps is setup with emergency restart.

you

when max children reached
When fpm pool busy..

emergency_restart_threshold = 0

;emergency_restart_interval = 0