Adjust PHP-FPM Limits

Rachel B.
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PHP-FPM is a popular PHP FastCGI implementation that can drastically improve website loading time and resource utilization on your server. There are, however, some settings to be aware of when using PHP-FPM, which may need to be adjusted depending on the needs of your website or application and the traffic received.

Specifically, these settings are Max Requests, Max Children, and Process Idle Timeout. If these values are not set high enough, your website may experience 503 or 504 errors. Here we detail the steps to adjust these VPS or Dedicated server settings.

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Modify PHP-FPM Settings

IMPORTANT: This solution will require root access. If this needs to be obtained, follow the guide on requesting root access.

  1. Log into Root WHM
  2. Navigate to Software -> MultiPHP Manager
    WHMMultiPHPManager.PNG
  3. To adjust limits for all domains
    1. On the System Settings tab, click the Manage Settings button
      WHMMultiPHPManagerManageSettings.PNG
  4. To adjust limits for a single domain
    1. Navigate to the User Domain Settings tab
      WHMMultiPHPManagerUserDomainSettings.PNG
    2. Click the PHP-FPM Settings button beside the applicable domain
      WHMMultiPHPManagerDomainFPMSettings.PNG
  5. Adjust the values as needed
    TIP: See the section at the end of this article for recommended settings.
    1. Max Requests controls how many requests are served by a process (Max Children) before killing and spawning a new process
    2. Max Children is the number of PHP-FPM processes to spawn to process PHP code for web server requests
    3. Process Idle Timeout is the number of seconds after which an idle process is set to be killed so it releases CPU time and RAM
      WHMMultiPHPManagerFPMLimits.PNG
  6. Click the Update button
    WHMMultiPHPManagerFPMLimitsUpdate.PNG
  7. Navigate to Restart Services>PHP-FPM service for Apache
    WHMRestartFPM.PNG
  8. Click the Yes button to restart the PHP-FPM service
    WHMRestartFPMConfirm.PNG

Recommended Settings

IMPORTANT: These recommendations are general guidelines and are not always the most appropriate settings for all server environments. PHP-FPM settings should be adjusted according to your server resources and your website(s) or application(s) needs. Please see cPanel's documentation for more details on PHP-FPM Performance Tuning.
CAUTION: It's safer to increase these values a little bit at a time.  Raising any of these settings too high can cause services on the server to crash due to running out of memory.

  1. Safe limits for VPS systems
    Max Requests: 80
    Max Children: 17
    Process Idle Timeout: 10
  2. Safe limits for Dedicated servers
    Max Request: 250
    Max Children: 25
    Process Idle Timeout: 10

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