Multithreading in PHP

Multi-threading in PHP
Dimitriy Remerov

Scopes
CURL bots
Creating files such as PDF, DOC, etc.
Cycles or calculation tasks optimization

CURL bots
If you need parallel CURL downloads, you actually don't need multi-processing, because you can use curl_multi_* functions.

Ways of using with web server
Within web server environment you can run processes in background via exec() this way:
exec ( '/path/cmd >/dev/null 2>&1 &' ) ;
Don't forget to escapeshellarg() your arguments if you are going to pass any.

PCNTL extension
PHP have the Process Control extension.
You can use it if you built your PHP with
--enable-pcntl option.
PCNTL doesn't work on Windows and should not be used within a web server environment.

ZendX_Console_Process_Unix
There is a wrapper for PCNTL that allows developers to spawn an object as a new process, and so do multiple tasks in parallel on console environments.
It works only on *nix based systems only with CGI or CLI environment. Additionally, the shmop_* , pcntl_* and posix_* modules are required.

Simple Usage
class MyProcess extends ZendX_Console_Process_Unix
{
protected function _run ()
{
for ( $i = 0 ; $i < 10 ; $i ++ ) {
// Doing something really important which can't wait:
sleep ( 1 ) ;
}
}
}

Simple Usage
$process1 = new MyProcess () ;
$process1 -> start () ;
$process2 = new MyProcess () ;
$process2 -> start () ;
while ( $process1 -> isRunning () || $process2 -> isRunning ()) {
sleep ( 1 ) ;
}
echo 'All processes completed' ;

Other methods
setVariable() and getVariable() can be used from both the parent- and the child process to share variables. To observe the alive status, the child process should call _setAlive() in a frequent interval, so that the parent process can check the last alive time via getLastAlive() . To get the PID of the child process, the parent can call getPid() .

Other languages
Don't forget that a web application doesn't have to be written completely in one language.
There is an approach that called 'problem picks the language'.
Since PHP is not initially built for such things, you can use other languages for your multi-processing tasks.

Multithreading in PHP

by dimitriyremerov on Jun 11, 2010

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