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Question: Unable to access website: [pool example.com] seems busy (you may need to increase pm.start_servers, or pm.min/max_spare_servers), spawning 8 children, there are 1 idle, and 49 total children


Applicable to:

• Plesk for Linux

Symptoms

• Plesk Obsidian running on a Linux-based operating system

• Unable to access website the website example.com with 502 Bad Gateway or 503 Service Temporarily Unavailable errors showing in a browser

• The following error can be found in the log file for the PHP version that this website is configured to use (for example /var/log/plesk-php74-fpm/error.log):

WARNING: [pool example.com] seems busy (you may need to increase pm.start_servers, or pm.min/max_spare_servers), spawning 8 children, there are 0 idle, and 129 total children

• The Apache error log for the website /var/www/vhosts/example.com/logs/example.com/error_log contains an error that is similar to the following:

• AH01067: Failed to read FastCGI header, referer: https://example.com/testpage.php

Cause

Some or all values for the PHP FastCGI Process Manager (PHP-FPM) directives below were exceeded by the related website:

• pm.start_servers
• pm.min_spare_servers
• pm.max_spare_servers

Resolution


                                        Solution I

1.Log into Plesk.

2.Go to Domains > example.com > PHP Settings > PHP-FPM settings section.

3.Change pm from dynamic to ondemand

4.Press the OK button to apply the change

Note: after applying the steps above, the RAM consumption and load on the server can be increased


                                        Solution II


1.Log into Plesk.

2.Go to Domains > example.com > PHP Settings > PHP-FPM settings section.

3.Increase values for the directives pm.start_servers, pm.min_spare_servers, pm.max_spare_servers and press the OK button to apply the changes


Additional information

Plesk for Linux services logs and configuration files

PHP: Configuration - Manual