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Advanced LSPHP Configuration

PHP Max Connections

suEXEC

LSWS offers three different PHP suEXEC modes: Worker, Daemon, and ProcessGroup.

In suEXEC PHP, LSWS allows you to control the number of PHP processes per user.

  1. Worker: Concurrency is controlled by the PHP suEXEC Max Conn setting Configuration > Server > General > PHP suEXEC Max Conn. This controls the number of PHP processes allowed per user.
  2. Daemon: Same as above. Concurrency is controlled by the PHP suEXEC Max Conn setting Configuration > Server > General > PHP suEXEC Max Conn. This controls the number of PHP processes allowed per user.
  3. ProcessGroup: The PHP suEXEC Max Conn setting controls the default concurrency.

PHP suEXEC Max Connections can be customized or overridden at virtual host and account level with the LSPHP_Workers directive in an Apache configuration file for all three modes: ProcessGroup, Daemon, and Worker.

Example

The PHP suEXEC Max Conn setting in the WebAdmin Console is set to 40, but you would like to raise it to 100 for a particular account. Add the following to the account's Apache virtual host configuration to override the global WebAdmin setting:

<IfModule LiteSpeed>
LSPHP_Workers 100
</IfModule>

Tip

If you are in a control panel environment and you get an error similar to the following:

[STDERR] Reached max children process limit: 10, extra: 3, current: 13, please increase LSAPI_CHILDREN` in `stderr.log

try to increase the PHP suEXEC Max Conn setting, found under Configuration > Server > General > Using Apache Configuration Filenot the LSAPI_CHILDREN setting in External Apps.

Non-suEXEC

LSWS offers two non-suEXEC PHP modes: Worker and ProcessGroup.

In non-suEXEC modes, there is only one PHP user. PHP concurrency is thus controlled by the the number of connections allowed between LSWS and the PHP engine: the External Application Max Connections setting found at Configuration > Server > External App > your_external_application.

You must make sure that your external application is also supplied with enough processes to serve these connections. The number of processes should always be set to be equal the Max Connections. This is set differently depending on your PHP mode:

  1. Worker: Simply set the Instances setting at Configuration > Server > External App > your_external_application.
  2. ProcessGroup: In ProcessGroup, the Instances setting must be set to 1. Control the number of processes instead with the PHP_LSAPI_CHILDREN environment variable.

Determining Which PHP Setup is in Use

If you are unsure which PHP setup you are using, ask yourself these questions:

  • Is the PHP suEXEC setting set to Yes or User's Home Directory Only? If so, then you are using suEXEC. If not, then you are not using suEXEC.

  • Is the Run on Start Up setting set to Yes (Daemon mode)? If so, then you are running Daemon mode. If not, then you are running Worker mode.

  • Do you have an LSPHP_ProcessGroup on directive in your Apache configuration files? If so, then users with that configuration are using ProcessGroup mode. (This can be set at the server or virtual host level.)
  • Is Instances set to 1? If so, you are running ProcessGroup mode. If not, you are running Worker mode.

These setups are explained further in PHP Process Modes.)

Troubleshooting Max Connections

Reached Max Children Process Limit

Let's say you have increased LSAPI_CHILDREN from 20 to 50, but you are still experiencing an error message like this:

Reached max children process limit: 15, extra: 5, current: 20, please increase LSAPI_CHILDREN.

Why?

In PHP suEXEC ProcessGroup mode, the instruction increase LSAPI_CHILDREN is actually asking you to increase the PHP SuEXEC Max Conn setting, not the PHP external app setting for LSAPI_CHILDREN.

You may not want to increase PHP SuEXEC Max Conn because it is a global setting applied to all virtual hosts. In this case you can increase PHP processes for only one virtual host via LSPHP_Workers in that vhost's configuration, like so:

<IfModule LiteSpeed>
LSPHP_Workers 50
</IfModule>

Another option may be to use the LSAPI_EXTRA_CHILDREN environment variable. It cannot be overridden.

Increasing LSAPI_CHILDREN will allow more foreground PHP processes running. Increasing LSAPI_EXTRA_CHILDREN will allow more background PHP processes running.

More details about this configuration can be found in the LiteSpeed SAPI Configuration documentation.

Tip

You should verify whether it is normal to have so many PHP processes. Try enabling LiteSpeed Cache to avoid having to deal with a high number of PHP processes.

New PHP suEXEC Max Conn Being Ignored

Let's say you've changed PHP suEXEC Max Conn from 10 to 20. Error messages inconsistently list the old value (10) and the new value (20). Why?

(14715) Reached max children process limit: 10, extra: 3, current: 13, busy: 12, please increase LSAPI_CHILDREN.
(28253) Reached max children process limit: 20, extra: 6, current: 26, busy: 26, please increase LSAPI_CHILDREN.
(14715) Reached max children process limit: 10, extra: 3, current: 13, busy: 12, please increase LSAPI_CHILDREN.
(28253) Reached max children process limit: 20, extra: 6, current: 26, busy: 26, please increase LSAPI_CHILDREN.

You must restart LiteSpeed Web Server to apply your changes to PHP suEXEC Max Conn:

service lsws restart

If you are running LSWS 5.3+ you will also need to restart any detached PHP processes:

killall lsphp

Last update: March 24, 2023