php-src/sapi/litespeed

Introduction

LiteSpeed SAPI module is a dedicated interface for PHP integration with LiteSpeed Web Server. LiteSpeed SAPI has similar architecture to the FastCGI SAPI with there major enhancements: better performance, dynamic spawning and PHP configuration modification through web server configuration and .htaccess files.

A simple benchmark test ("hello world") shows that PHP with LiteSpeed SAPI has 30% better performance over PHP with FastCGI SAPI, which is nearly twice the performance that Apache mod_php can deliver.

A major drawback of FastCGI PHP comparing to Apache mod_php is lacking the flexibilities in PHP configurations. PHP configurations cannot be changed at runtime via configuration files like .htaccess files or web server's virtual host configuration. In shared hosting environment, each hosting account will has its own open_basedir overridden in server configuration to enhance server security when mod_php is used. Usually, FastCGI PHP is not an option in shared hosting environment due to lacking of this flexibility. LiteSpeed SAPI is carefully designed to address this issue. PHP configurations can be modified the same way as that in mod_php with the same configuration directives.

PHP with LiteSpeed SAPI is highly recommended over FastCGI PHP for PHP scripting with LiteSpeed web server.

Building PHP with LiteSpeed SAPI

You need to add --enable-litespeed to the configure command to build PHP with LiteSpeed SAPI, all other SAPI related configure options should be removed.

For example:

./configure --enable-litespeed
make

You should find an executable called lsphp under sapi/litespeed/ directory after the compilation succeeds. Copy it to lsws/fcgi-bin/lsphp or wherever you prefer, if LiteSpeed web server has been configured to run PHP with LiteSpeed SAPI already, you just need to overwrite the old executable with this one and you are all set.

Start PHP from command line

Usually, lsphp is managed by LiteSpeed web server in a single server installation. lsphp can be used in clustered environment with one LiteSpeed web server at the front, load balancing lsphp processes running on multiple backend servers. In such environment, lsphp can be start manually from command with option -b <socket_address>, socket address can be IPv4, IPv6 or Unix Domain Socket address.

For example:

./lsphp -b [::]:3000

have lsphp bind to port 3000 on all IPv4 and IPv6 address,

./lsphp -b *:3000

have lsphp bind to port 300 on all IPv4 address,

./lsphp -b 192.168.0.2:3000

have lsphp bind to address 192.168.0.2:3000,

./lsphp -b /tmp/lsphp_manual.sock

have lsphp accept request on Unix domain socket /tmp/lsphp_manual.sock.

Using LiteSpeed PHP with LiteSpeed Web Server

Detailed information about how to configure LiteSpeed web server with PHP support is available from LiteSpeed website.

Usually, PHP support has been configured out of box, you don't need to change it unless you want to change PHP interface from FastCGI to LiteSpeed SAPI or vice versa.

Brief instructions are as follow:

1. Login to web administration interface, go to 'Server'->'Ext App' tab, add an external application of type "LSAPI app", "Command" should be set to a shell command that executes the PHP binary you just built. "Instances" should be set to "1". Add "LSAPI_CHILDREN" environment variable to match the value of "Max Connections". More tunable environment variable described below can be added.

2. Go to 'Server'->'Script Handler' tab, add a script handler configuration: set 'suffix' to 'php', 'Handler Type' to 'LiteSpeed API', 'Handler Name' should be the name of external application just defined.

3. Click 'Apply Changes' link on the top left of the page, then click 'graceful restart'. Now PHP is running with LiteSpeed SAPI.

Tunings

There are a few environment variables that can be tweaked to control the behavior of LSAPI application.

• LSAPI_CHILDREN or PHP_LSAPI_CHILDREN (default: 0)

  There are two ways to let PHP handle multiple requests concurrently, Server Managed Mode and Self Managed Mode. In Server Managed Mode, LiteSpeed web server dynamically spawn/stop PHP processes, in this mode "Instances" should match "Max Connections" configuration for PHP external application. To start PHP in Self Managed Mode, "Instances" should be set to "1", while LSAPI_CHILDREN environment variable should be set to match the value of "Max Connections" and greater than 1. Web Server will start one PHP process, this process will start/stop children PHP processes dynamically based on on demand. If LSAPI_CHILDREN less or equal to 1, PHP will be started in server managed mode.

  Self Managed Mode is preferred because all PHP processes can share one shared memory block for the opcode cache.

  Usually, there is no need to set value of LSAPI_CHILDREN over 100 in most server environments.

• LSAPI_AVOID_FORK (default: 0)

  LSAPI_AVOID_FORK specifies the policy of the internal process manager in "Self Managed Mode". When set to 0, the internal process manager will stop and start children process on demand to save system resource. This is preferred in a shared hosting environment. When set to 1, the internal process manager will try to avoid freqently stopping and starting children process. This might be preferred in a dedicate hosting environment.

• LSAPI_EXTRA_CHILDREN (default: 1/3 of LSAPI_CHILDREN or 0)

  LSAPI_EXTRA_CHILDREN controls the maximum number of extra children processes can be started when some or all existing children processes are in malfunctioning state. Total number of children processes will be reduced to LSAPI_CHILDREN level as soon as service is back to normal. When LSAPI_AVOID_FORK is set to 0, the default value is 1/3 of LSAPI_CHILDREN, When LSAPI_AVOID_FORK is set to 1, the default value is 0.

• LSAPI_MAX_REQS or PHP_LSAPI_MAX_REQUESTS (default value: 10000)

  This controls how many requests each child process will handle before it exits automatically. Several PHP functions have been identified having memory leaks. This parameter can help reducing memory usage of leaky PHP functions.

• LSAPI_MAX_IDLE (default value: 300 seconds)

  In Self Managed Mode, LSAPI_MAX_IDLE controls how long a idle child process will wait for a new request before it exits. This option help releasing system resources taken by idle processes.

• LSAPI_MAX_IDLE_CHILDREN (default value: 1/3 of LSAPI_CHILDREN or LSAPI_CHILDREN)

  In Self Managed Mode, LSAI_MAX_IDLE_CHILDREN controls how many idle children processes are allowed. Excessive idle children processes will be killed by the parent process immediately. When LSAPI_AVOID_FORK is set to 0, the default value is 1/3 of LSAPI_CHIDLREN, When LSAPI_AVOID_FORK is set to 1, the default value is LSAPI_CHILDREN.

• LSAPI_MAX_PROCESS_TIME (default value: 300 seconds)

  In Self Managed Mode, LSAPI_MAX_PROCESS_TIME controls the maximum processing time allowed when processing a request. If a child process can not finish processing of a request in the given time period, it will be killed by the parent process. This option can help getting rid of dead or runaway child process.

• LSAPI_PGRP_MAX_IDLE (default value: FOREVER)

  In Self Managed Mode, LSAPI_PGRP_MAX_IDLE controls how long the parent process will wait before exiting when there is no child process. This option helps releasing system resources taken by an idle parent process.

• LSAPI_PPID_NO_CHECK

  By default a LSAPI application check the existence of its parent process and exits automatically if the parent process died. This is to reduce orphan process when web server is restarted. However, it is desirable to disable this feature, such as when a LSAPI process was started manually from command line. LSAPI_PPID_NO_CHECK should be set when you want to disable the checking of existence of parent process. When PHP is started by -b option, it is disabled automatically.

Compatibility with Apache mod_php

LSAPI PHP supports PHP configuration overridden via web server configuration as well as .htaccess.

Since 4.0 release apache_response_headers function is supported.

Contact

For support questions, please post to the free support forum:

For bug report, please send bug report to bug [at] litespeedtech.com.