- Plesk 12.5 for Linux
- Plesk Onyx for Linux
The Apache web-server keeps going down. The following error message appears in the Apache logfile /var/log/apache2/error.log:
CONFIG_TEXT: [mpm_prefork:error] [pid 14998] AH00161: server reached MaxRequestWorkers setting, consider raising the MaxRequestWorkers setting
There is a high load on the server. Operations hang or take a lot of time to execute.
The MaxRequestWorkers limit has been reached.
Increase the MaxRequestWorkers and ServerLimit limits:
Connect to the Plesk server via SSH.
Open the corresponding file in a text editor and increase the values of the following directives:
For CentOS/RHEL-based distributions: /etc/httpd/conf.modules.d/01-cgi.conf
CONFIG_TEXT: <IfModule mpm_prefork_module>
LoadModule cgi_module modules/mod_cgi.so
For Debian/Ubuntu-based distributions: /etc/apache2/mods-enabled/mpm_event.conf and /etc/apache2/mods-enabled/mpm_prefork.conf
CONFIG_TEXT: MaxRequestWorkers 300
Note: Values are provided as an example, they should be adjusted according the server capabilities and load. Default
MaxRequestWorkersvalue is 256. Be careful, too high values of
ServerLimitdirectives may cause Apache to become unresponsive.
for CentOS/RHEL-based distributions:
# service httpd restart
for Debian/Ubuntu-based distributions:
# service apache2 restart
- Apache is not responding: fork: Unable to fork new process
- Apache crashes on reload and websites show 502 Bad Gateway: seg fault or similar nasty error detected in the parent process
- Apache hangs or crashes on reload
More about Apache performance tuning and the MaxRequestWorkers directive: