Why is there a constant increase in RAM consumption in php-fpm?

Question

PHP

In php-fpm, there is a constant increase in RAM consumption, ~ + 1% per day.
And after 3 weeks you have to restart the server due to lack of RAM.
I noticed this when I typed top in the terminal:

466 root      20   0  469980  43080  35132 S   0.0  0.4   1:08.70  `- php-fpm: master process (/opt/plesk/php/7.1/etc/php-fpm.conf)             
  909 web  20   0 1610096 1.121g  27336 S   0.3  9.8  25:50.36      `- php-fpm: pool сайт                                          
  911 web  20   0 1609788 1.119g  25584 S   0.7  9.7  26:15.04      `- php-fpm: pool сайт

This is the first time I've come across this, why can this happen, why don't they close for so long? Prompt in what direction to dig?

Answer 1

Set pm.max_requeststo recreate processes after a certain number of processed requests.

Answer 2

I believe that the memory is not released due to the fact that its consumption is caused by an increase in the number of HTTP connections, with a DBMS, or something else.
You need to profile the application to know the reason.