Apache MaxRequestWorkers and PHP FPM Max Children

chcw

• June 30, 2023 11:42

Hi, I read the following article to try to understand Apache MaxRequestWorkers and PHP FPM Max Children: mpm_common - Apache HTTP Server Version 2.4, MaxRequestWorkers is the max number of processes that Apache can allow. For non-thread mode(

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  cPRex Jurassic Moderator

  • June 30, 2023 18:07

  Hey there!

  1. Though I am in worker mode, the MaxRequestWorkers is set to 150 and system max is 256, much higher than default 16, why? It seems the value is like to be a default for prefork mode.

  
  cPanel has always used 256 for this limit, and you can read more about the defaults here:

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  chcw

  • June 30, 2023 18:48

  Hi, cPRex If I understand correct, then: 1. A PHP FPM Child Process is also a Apache Process. 2. The Apache processes = PHP FPM Child Processes for PHP requests + other processes for non PHP requests, such as images, js, CSS, etc. 3. The total requests that Apache can handle = Total requests PHP FPM can handle + Total requests that other processes can handle. If 2 is correct, then MaxRequestWorkers must be > PHP FPM Max Children, otherwise, there will be no available processes for non PHP requests. If 3 is correct, then the total requests Apache can handle = PHP FPM Max Request * Max Children + Other Multi-thread process * Children per thread + Other Single-thread process.

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  cPRex Jurassic Moderator

  • June 30, 2023 19:40

  That all sounds correct to me!

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  chcw

  • July 01, 2023 02:38

  Thank you.

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  cPRex Jurassic Moderator

  • July 02, 2023 19:04

  Sure thing!

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