Let’s break down how to verify the active pm.max_children value for your PHP-FPM instance, plus a quick note on why your change might not have taken effect yet:

1. Use phpinfo() to See Runtime Configuration #

Create a temporary PHP file (e.g., info.php) in your web server’s document root with this content:

<?php
phpinfo();
?>

Access this file via your browser (like http://your-domain/info.php), then use your browser’s search function to look for pm.max_children. You’ll find it under the PHP-FPM section—make sure to check the entry for your "www" pool specifically.

⚠️ Critical: Delete this file right after checking. Exposing phpinfo() publicly is a serious security risk.

2. Check via PHP-FPM’s Command Line Tools #

For PHP 7.0 FPM, run these commands directly on your server terminal:

• To test and print the parsed configuration (including pool settings):

  php-fpm7.0 -tt
  

  Scan the output for pm.max_children under the [pool www] block. This shows the value PHP-FPM will use with your current config files.
• To fetch runtime info similar to phpinfo() via CLI:

  php-fpm7.0 -i | grep "pm.max_children"
  

3. Inspect Running PHP-FPM Processes #

To confirm the configuration loaded by the active PHP-FPM daemon:

1. Get the main PHP-FPM process ID:

   pidof php-fpm7.0
   

2. View its command line arguments to verify which config file it’s using:

   cat /proc/$(pidof php-fpm7.0)/cmdline | tr '\0' ' '
   

   Look for a --fpm-config flag or the default path (/etc/php/7.0/fpm/php-fpm.conf, which includes pool configs like www.conf).

A Quick Fix for Your Original Issue #

Wait—you mentioned restarting Apache after modifying www.conf, but PHP-FPM is a separate service from Apache. Changes to PHP-FPM configs require restarting the PHP-FPM service itself, not Apache. Try this command to apply your change:

sudo systemctl restart php7.0-fpm
# Or if using init.d:
sudo service php7.0-fpm restart

That’s likely why your pm.max_children update didn’t take effect initially!

内容的提问来源于stack exchange，提问作者Tilman