Run PHP without Timeouts

This wiki covers how to set up LiteSpeed Web Server so that a long-running PHP script will never timeout.

Some PHP scripts need to run for long periods of time without interruption. Examples include WordPress modules such as BackupBuddy, ImportBuddy, or any other module that relies on a WordPress built-in cron job. Whenever a PHP application rebuilds MySQL indexes, the process may run for a long time.

In Apache mod_php, the ignore_user_abort variable allows a user to trigger a long-running process and then close the browser or navigate away from the page without killing the PHP/MySQL process. This environment variable is not supported by LSWS.

Generally, allowing a PHP script to run forever is not desirable. Thus there are a number of features that may prevent a PHP process from running as long as possible. You may need to set up more than one of the following configurations to ensure your application works correctly.

When a user closes a connection (by closing a window, for example), LSWS will abort processing that PHP script by killing the PHP process. This is to avoid wasting system resources and prevent certain types of DoS attacks.

In some cases, though, it is preferable to not to abort the PHP script regardless of whether the connection is still open. For example, Wordpress built-in cron jobs start a background job by sending a request to wp-cron.php then immediately closing the connection without waiting for response. In order for the cron job to complete, though, the web server must keep the PHP engine running without interruption.

Aborting for a broken connection can be turned off at the server level in LSWS's WebAdmin console or by using the “noabort” environment variable.

WebAdmin console > Configuration > Server > General > External Application Abort

Set External Application Abort to “No Abort” to stop all applications from aborting even when a connection has been broken.

Aborting for a broken connection can be turned off by using the request-level “noabort” environment variable. This can be done in a rewrite rule or using the SetEnv/SetEnvIf directives. “noabort” is a LiteSpeed-specifc environment variable.

The [E=noabort:1] flag can be added to any rewrite rule. The rewrite rule can be in an Apache .htaccess file or vhost-level configuration file. The rewrite flag should usually be used in ONE account only. If you need to do a server-level configuration that will apply to all accounts (though perhaps only for certain scripts), you should use the SetEnvIf directive.

• For all requests.

RewriteEngine On
RewriteRule .* - [E=noabort:1]

• For wp-cron.php, backupbuddy.php, and importbuddy.php only.

RewriteEngine On
RewriteRule (wp-cron|backupbuddy|importbuddy)\.php - [E=noabort:1]

• For all requests.

SetEnv  noabort 1

• For certain URLs (i.e. wp-cron.php, backupbuddy.php, and importbuddy.php).

SetEnvIf Request_URI "(wp-cron|backupbuddy|importbuddy)\.php" noabort

Note: Rewrite rules cannot be easily inherited. Thus, if you want to turn off aborting for a broken connection for a certain URL in all accounts, the SetEnvIf directive should be used.

If a script does not send back anything for long time, server may close the client connection based on connection timeout, it means that the request could be aborted by the server or the client cannot see the result even though the script may continue to run till it finishes, depends on whether “noabort” has been set or not. You may want to prevent connection from being timed out some times.

Admin CP => Configuration => Server => Tuning => Connection Timeout (secs)

Similar to “noabort” environment, you can add “noconntimeout” environment variable via rewrite rule or SetEnv/SetEnvIf to turn off connection timeout.

RewriteEngine On
RewriteRule .* - [E=noconntimeout:1]

RewriteRule (wp-cron|backupbuddy|importbuddy)\.php - [E=noconntimeout:1]

SetEnvIf Request_URI "(wp-cron|backupbuddy|importbuddy)\.php" noconntimeout

It can be combined with “noabort” environment variable.

RewriteRule (wp-cron|backupbuddy|importbuddy)\.php - [E=noabort:1, E=noconntimeout:1]

equivalent SetEnvIf directive is

SetEnvIf Request_URI "(wp-cron|backupbuddy|importbuddy)\.php" noabort noconntimeout

    max_execution_time=36000

This is the time that spent in the PHP process itself (user time), does not include time spent in system calls or network I/O. Usually it takes more time to have it triggered.

 Admin CP => Configuration => Server(or Vhost) => External App => lsphp5 => Environments

In Self Managed Mode, LSAPI_MAX_PROCESS_TIME (default 3600 seconds) controls the maximum processing time allowed when processing a request. If a child process cannot finish processing the request in the given time period, it will be killed by the parent process. This option can get rid of a dead or a runaway child process.

One of our customers has had success with the following PHP code. Code:

<?php
//avoid apache to kill the php running
ignore_user_abort(true);
//start buffer output
ob_start();

echo "show something to user";
//close session file on server side to avoid blocking other requests
session_write_close();

//send length header
header("Content-Length: ".ob_get_length());
header("Connection: close");
//really send content, can't change the order:
//1.ob buffer to normal buffer, 
//2.normal buffer to output
ob_end_flush();
flush();
//continue do something on server side
ob_start();
//replace it with the background task
sleep(50); 
ob_end_clean();
?>

Note: You need to turn off keepalive for this request, which can be done with a rewrite rule.