Multithreading in php

Published by Tudor on January 2, 2009 | 113 Responses

Some time ago, I’ve wrote a small server in PHP. Nothing fancy. It would listen on a socket and when a new client would connect, the server would start a new thread and manage the client’s request. Since threading it’s not available in PHP, I’ve emulated the threads with child processes which are available in php. A thread object simply encapsulates a new process started with pnctl_fork() and emulates – to some extent – the behaviour of the java.lang.Thread class, the main difference being that in my implementation, you don’t extend the Thread class, you simply provide the name of a callback function in the constructor.

A simple multithreaded application would look like this:

require_once( 'Thread.php' );

// test to see if threading is available
if( ! Thread::available() ) {
    die( 'Threads not supported' );
}

// function to be ran on separate threads
function paralel( $_limit, $_name ) {
    for ( $index = 0; $index &lt; $_limit; $index++ ) {
        echo 'Now running thread ' . $_name . PHP_EOL;
        sleep( 1 );
    }
}

// create 2 thread objects
$t1 = new Thread( 'paralel' );
$t2 = new Thread( 'paralel' );

// start them
$t1-&gt;start( 10, 't1' );
$t2-&gt;start( 10, 't2' );

// keep the program running until the threads finish
while( $t1-&gt;isAlive() &amp;&amp; $t2-&gt;isAlive() ) {
    sleep(1);
}

require_once( 'Thread.php' );

// test to see if threading is available

if( ! Thread::available() ) {

die( 'Threads not supported' );

}

// function to be ran on separate threads

function paralel( $_limit, $_name ) {

for ( $index = 0; $index < $_limit; $index++ ) {

echo 'Now running thread ' . $_name . PHP_EOL;

sleep( 1 );

}

// create 2 thread objects

$t1 = new Thread( 'paralel' );

$t2 = new Thread( 'paralel' );

// start them

$t1->start( 10, 't1' );

$t2->start( 10, 't2' );

// keep the program running until the threads finish

while( $t1->isAlive() && $t2->isAlive() ) {

sleep(1);

}

This will display Now running thread 1 and Now running thread 2 messages with 1 second delays. I know, not that impressive, but hey, it’s multithreaded.

PHP threading will only work on Unix and Linux systems, because pnctl_fork is nothing more than a wrapper for the fork() function from unistd.h and it’s not available under Microsoft operating systems.

I know that the first example was pretty lame, but there are some more interesting things you could do with threads in PHP. For instance, if you need to do some server side processing of all the images in a directory, a multithreaded approach will be much faster.

require_once( 'Thread.php' );

// test to see if threading is available
if( ! Thread::available() ) {
    die( 'Threads not supported' );
}

// define the function to be run as a separate thread
function processImage( $_image ) {
    // expensive image processing logic here
}

$threads = array();
$index = 0;

foreach( new DirectoryIterator( '/path/to/images' ) as $item ) {
    if( $item-&gt;isFile() ) {
        $threads[$index] = new Thread( 'processImage' );
        $threads[$index]-&gt;start( $item-&gt;getPathname() );
        ++$index;
        }
}

// wait for all the threads to finish
while( !empty( $threads ) ) {
    foreach( $threads as $index =&gt; $thread ) {
        if( ! $thread-&gt;isAlive() ) {
            unset( $threads[$index] );
        }
    }
    // let the CPU do its work
    sleep( 1 );
}

require_once( 'Thread.php' );

// test to see if threading is available

if( ! Thread::available() ) {

die( 'Threads not supported' );

}

// define the function to be run as a separate thread

function processImage( $_image ) {

// expensive image processing logic here

}

$threads = array();

$index = 0;

foreach( new DirectoryIterator( '/path/to/images' ) as $item ) {

if( $item->isFile() ) {

$threads[$index] = new Thread( 'processImage' );

$threads[$index]->start( $item->getPathname() );

++$index;

}

// wait for all the threads to finish

while( !empty( $threads ) ) {

foreach( $threads as $index => $thread ) {

if( ! $thread->isAlive() ) {

unset( $threads[$index] );

}

// let the CPU do its work

sleep( 1 );

}

PS: it’s a bad practice to keep looping in order to wait for a thread to finish. An ongoing empty loop will quickly boost your CPU ‘s load to 100%. If you need your processor free (and you need it), simply send the current (looping) thread to sleep and let the others execute.

// wait for thread - bad approach (overloads the CPU)
while ( $thread-&gt;isAlive() ) {
}

// wait for thread - correct approach
while( $thread-&gt;isAlive() ) {
    sleep( 1 ); 
}

// wait for thread - bad approach (overloads the CPU)

while ( $thread->isAlive() ) {

}

// wait for thread - correct approach

while( $thread->isAlive() ) {

sleep( 1 );

}

Download Thread.php

Here you go: Thread.php. Just click the link to download the class. If you have a better approach to this issue or think that the original class could be improved, don’t be shy and leave a comment below. Credits will be given.

Posted in Programming Tagged extreme php, multithreading, php

113 Responses

Multithreading in php | PHP-Blog.com January 2, 2009 at 8:01 am | Permalink

[…] the original: Multithreading in php Related ArticlesBookmarksTags PHP PHP is a computer scripting language. Originally […]
Raul January 27, 2009 at 11:33 pm | Permalink | Reply

Thanks! 😉
Tudor January 27, 2009 at 11:37 pm | Permalink | Reply

Did you try it on a live project? Can we see it at work? 😛
Raul January 27, 2009 at 11:44 pm | Permalink | Reply

Unfortunatelly “live” , “at work” no because of M$ OS.
But i’ll use it for my scripts in Ubuntu! 😉
Tudor January 28, 2009 at 11:59 am | Permalink | Reply

I’ve used it on a project, but it’s only available in intranet. But it works and that’s all that matters. If you have any suggestions of improvement, so share 😉
upsemshop December 17, 2009 at 8:24 pm | Permalink | Reply

Hi guys,
My PC worked not correctly, too much mistakes and buggs. Please, help me to fix buggs on my computer.
My operation system is Win Vista.
Thx,
upsemshop
Joey February 1, 2010 at 6:51 am | Permalink | Reply

At line 170, there is an error.

pcntl_waitpid( $this->pid, $status = 0 );

You never use the variable $status anyway, so it doesn’t hurt. But if you ever decide to use the $status variable, passing in $status = 0 does not pass the variable to the function, it passes the value of the assignment, 0.

If you set your error reporting to strict, it will complain that:

“Only variables should be passed by reference”

Otherwise, thanks for sharing your code.
Tudor February 1, 2010 at 11:51 am | Permalink | Reply

10x man, I’ll look into it and fix it later today. Sometime bugs escape one programmer just to be caught by another. That’s the beauty of Open Source.
Tudor February 7, 2010 at 11:18 am | Permalink | Reply

I had a look at the code and it seems it was better the way it was. I made some tests, and, as if turned out, if I change that line and remove the $status variable, like such:

PHP

pcntl_waitpid( $this->pid, 0);

1

pcntl_waitpid( $this->pid, 0);

it will yield an fatal error, saying:

PHP

//Fatal error: Only variables can be passed by reference in Thread.php on line 170

1

//Fatal error: Only variables can be passed by reference in Thread.php on line 170

I always want to pass in 0 as an argument there, so there are two ways in which that can be achieved:

PHP

// 1. The long way $status = 0; pcntl_waitpid( $this->pid, $status); // 2. The short way pcntl_waitpid( $this->pid, $status = 0);

1
2
3
4
5
6

// 1. The long way
$status = 0;
pcntl_waitpid( $this->pid, $status);

// 2. The short way
pcntl_waitpid( $this->pid, $status = 0);

Hope it’s clear for everybody now.
Joey February 10, 2010 at 7:25 am | Permalink | Reply

Why do you want to pass a zero in there? That parameter is not expecting a _value_, it’s expecting a _reference_. PHP can can put the real status value in it and give it back to you so that you can check against it later.

See the functions pcntl_wif*()

I hope that made sense.
Tudor February 10, 2010 at 11:33 am | Permalink | Reply

I’ve browsed the manual, as this entry is over one year old and I can’t remember why I took some decisions back then. It seems that you must always pass in a variable for the status to the function, in order to work. I’m not interested in the returned status, so I’ve passed in a zero variable.
George March 30, 2010 at 10:25 am | Permalink | Reply

Thanks for the example code. Any idea how I would use that in an Apache server that executes PHP scripts? I’m on Ubuntu and it seems as if pcntl_fork() is not available in the PHP that is in the apache. I tried the solution in

http://www.php.net/manual/en/ref.pcntl.php#91224

but it does not seem to work for me.

Any ideas?

Thanks,

George
Tudor March 31, 2010 at 3:26 pm | Permalink | Reply

It won’t work like this. I think the best way to achieve multithreading is dropping PHP and switch to python or something else. Or rewrite in a different language the part you want to be multithreaded.
Zoli April 8, 2010 at 8:45 pm | Permalink | Reply

Hi,

The function I’d like to thread returns a string, is it possible to retrieve that somehow and let them set in a result array in the main code starting the threads for example?

Thanks in advance, Zoli

Tudor April 9, 2010 at 11:42 am | Permalink | Reply

Good one, Zoli! I’ll update the Thread.php file in the future. Until then, you need to do the following: add “return” in front of the call_user_func_array() and
call_user_func() calls so that the start() method will return the original function’s result. Like such:

// child
pcntl_signal( SIGTERM, array( $this, 'signalHandler' ) );
$arguments = func_get_args();
if ( !empty( $arguments ) ) {
    return call_user_func_array( $this->runnable, $arguments );
}
else {
    return call_user_func( $this->runnable );
}

exit( 0 );

// child

pcntl_signal( SIGTERM, array( $this, 'signalHandler' ) );

$arguments = func_get_args();

if ( !empty( $arguments ) ) {

return call_user_func_array( $this->runnable, $arguments );

}

else {

return call_user_func( $this->runnable );

}

exit( 0 );

This is untested code, but it *should* work!

sims April 29, 2010 at 12:55 pm | Permalink | Reply

Thanks for that. I learned a lot from your code. A suggestion to an otherwise excellent class:

It is allowed for the first parameter of call_user_func_array to be an array(class, ‘method’). So, there is a problem with function_exists in runnableOk. Besides, if it is_callable then function_exists. So I don’t think you need to check both.
Ricardo Sanchez May 5, 2010 at 6:36 pm | Permalink | Reply

Hi! Great script!

I’ve been testing the Zoli idea and the “return” aproximation and it does not work… mainly because the child dies and there is no communication between parent and child…

They are two separated processes, so… any idea to get returned data to the parent from the children function? Maybe sockets??

Ricardo Sanchez May 6, 2010 at 6:06 pm | Permalink | Reply

Hi! I’ve found how to return data from child to parent, using pipes:

In class Thread:

/**
 * Starts the thread, all the parameters are passed to the callback function
 * @return void
 */
public function start() {
    $status = 0;
            $results = null;
    $pid = pcntl_fork();
    
    if( $pid == -1 ) { //error forking, no child is created
        throw new Exception( $this->getError( Thread::COULD_NOT_FORK ), Thread::COULD_NOT_FORK );
    }else if ( $pid ) {// parent
        $this->pid = $pid; 

    } else { // child 
        $this->pid = posix_getpid();//pid (child)
        $this->ppid = posix_getppid();//pid (parent)
        
        pcntl_signal( SIGTERM, array( $this, 'signalHandler' ) );
        $array_args = func_get_args();
        if ( !empty( $array_args ) ) {
            $results = call_user_func_array( $this->runnable, $array_args );
        }else{
            $results = call_user_func( $this->runnable );
        }
    
        $pipe = "/tmp/pipe_"..$this->pid;//pid is known by parent
        
        if(!file_exists($pipe)) {//child talks to parent using this pipe
            umask(0);
            posix_mkfifo($pipe, 0600);
        }
        //we have to open the pipe and send the data serialized
        $pipe_descriptor = fopen($pipe, 'w');
        fwrite($pipe_descriptor, serialize( $results ) );
        
        //and kill the child using posix_kill ( exit(0) duplicates headers!! )
        posix_kill( $this->pid , SIGKILL);
        exit(0);
    }
}

/**

* Starts the thread, all the parameters are passed to the callback function

* @return void

public function start() {

$status = 0;

$results = null;

$pid = pcntl_fork();

if( $pid == -1 ) { //error forking, no child is created

throw new Exception( $this->getError( Thread::COULD_NOT_FORK ), Thread::COULD_NOT_FORK );

}else if ( $pid ) {// parent

$this->pid = $pid;

} else { // child

$this->pid = posix_getpid();//pid (child)

$this->ppid = posix_getppid();//pid (parent)

pcntl_signal( SIGTERM, array( $this, 'signalHandler' ) );

$array_args = func_get_args();

if ( !empty( $array_args ) ) {

$results = call_user_func_array( $this->runnable, $array_args );

}else{

$results = call_user_func( $this->runnable );

}

$pipe = "/tmp/pipe_"..$this->pid;//pid is known by parent

if(!file_exists($pipe)) {//child talks to parent using this pipe

umask(0);

posix_mkfifo($pipe, 0600);

}

//we have to open the pipe and send the data serialized

$pipe_descriptor = fopen($pipe, 'w');

fwrite($pipe_descriptor, serialize( $results ) );

//and kill the child using posix_kill ( exit(0) duplicates headers!! )

posix_kill( $this->pid , SIGKILL);

exit(0);

}

In function which uses Thread:

$sleep_microseconds = 200000; // we don't want to achieve 100% CPU load!

//start multiple threads!!
for ($i = 0; $i start( 'param1','param2' );
    }
}

//We are the parent... childs never reach this part of the code!!
//Parent has to read child's pipes... Communication between parents and childrens is necesary in our society!

while (!empty( $threads )){//while any child is alive...
    foreach($threads as $index => $thread){
        $child_pipe = "/tmp/pipe_".$thread->getPid();//this pipe communicate the parent with one of his childs... look at Thread->start() method, in both places (child and parent) the pipe name must be the same!
    
        if (file_exists($child_pipe)){//if pipe exists, we (the parent) open it, listen to our child, and when the child has finished, the child will die and the parent close the pipe between them
            $file_descriptor = fopen( $child_pipe, "r");
            $child_response = "";
            while (!feof($file_descriptor)){//while pipe is open, parent continues reading
                $child_response .= fread($file_descriptor, 8192);
            }
            //we have the child data in the parent, but serialized:
            $array_responses[ $index ] = unserialize( $child_response );
            
            //now, child is dead, and parent close the pipe
            unlink( $child_pipe );
            unset($threads[$index]);//and remove the child from our array
        }
    }
    //parent must sleep for a while, because we don't want to achieve 100% CPU load!
    usleep( $sleep_microseconds );
}

//now, we have all data from the forked children in $array_responses

$sleep_microseconds = 200000; // we don't want to achieve 100% CPU load!

//start multiple threads!!

for ($i = 0; $i start( 'param1','param2' );

}

//We are the parent... childs never reach this part of the code!!

//Parent has to read child's pipes... Communication between parents and childrens is necesary in our society!

while (!empty( $threads )){//while any child is alive...

foreach($threads as $index => $thread){

$child_pipe = "/tmp/pipe_".$thread->getPid();//this pipe communicate the parent with one of his childs... look at Thread->start() method, in both places (child and parent) the pipe name must be the same!

if (file_exists($child_pipe)){//if pipe exists, we (the parent) open it, listen to our child, and when the child has finished, the child will die and the parent close the pipe between them

$file_descriptor = fopen( $child_pipe, "r");

$child_response = "";

while (!feof($file_descriptor)){//while pipe is open, parent continues reading

$child_response .= fread($file_descriptor, 8192);

}

//we have the child data in the parent, but serialized:

$array_responses[ $index ] = unserialize( $child_response );

//now, child is dead, and parent close the pipe

unlink( $child_pipe );

unset($threads[$index]);//and remove the child from our array

}

//parent must sleep for a while, because we don't want to achieve 100% CPU load!

usleep( $sleep_microseconds );

}

//now, we have all data from the forked children in $array_responses

Shane Mc Cormack July 15, 2010 at 4:28 pm | Permalink | Reply

Further to the above, I was mistaken, that obviously doesn’t work, all it does is stop the warnings.

It only appeared to be working based on the input I was testing with, oh well.

Shane Mc Cormack July 15, 2010 at 2:50 pm | Permalink | Reply

I needed to pass a value by reference to the “threaded” function and noticed that in its current instance, this class only passes by ref, this was changed near line 147 by using:

$stack = debug_backtrace();
$arguments = array();
if (isset($stack[0]["args"])) {
    for($i=0; $i > count($stack[0]['args']); $i++) {
        $arguments[$i] = & $stack[0]['args'][$i];
    }
}

$stack = debug_backtrace();

$arguments = array();

if (isset($stack[0]["args"])) {

for($i=0; $i > count($stack[0]['args']); $i++) {

$arguments[$i] = & $stack[0]['args'][$i];

}

I’m not sure of the performance hit by doing this, but it works.

Tudor July 15, 2010 at 9:07 pm | Permalink | Reply

Encapsulate the value you want to pass on in an object. Since objects are always passed by reference in PHP, it should do the trick.
Jelle De Loecker August 21, 2010 at 2:18 am | Permalink | Reply

The threading itself worked like a charm, unfortunately my singleton mysql wrapper wouldn’t work with it as it always complained about the database going away.
Tudor August 24, 2010 at 11:38 am | Permalink | Reply

Try opening a permanent connection to the MySQL server!
[PHP-mencoder] Des filigranes (watermark) dans vos flv avec PHP et mencoder « Emilien DAMART September 16, 2010 at 3:13 am | Permalink

[…] l’ai donc réécrit en PHP en utilisant cette classe qui permet de gérer des threads (Attention, celle-ci utilise l’extension pcntl de PHP). […]
Steponas October 22, 2010 at 1:03 pm | Permalink | Reply

Thanks for the great class! This has helped me with the question “What should I use for my PHP project as a command-line multithreaded net app: Python or Java”. I’ll go all the way with PHP.

Mark October 31, 2010 at 12:06 am | Permalink | Reply

Thanks for this, I’d like to suggest an addition. I needed to call a method in a class, but runnableOK was returning false as a method isn’t a function… So, assuming i’m passing the object instance and method name in an array like this: $t = new Thread(array($this, ‘publicmethod’)), the following change will allow it.

public static function runnableOk( $_runnable ) {
    // check for method existance 
    if (is_array($_runnable)){
        return (method_exists(get_class($_runnable[0]), $_runnable[1]) && is_callable($_runnable) );
    }
    else{
        return ( function_exists( $_runnable ) && is_callable( $_runnable ) );
    }
}

public static function runnableOk( $_runnable ) {

// check for method existance

if (is_array($_runnable)){

return (method_exists(get_class($_runnable[0]), $_runnable[1]) && is_callable($_runnable) );

}

else{

return ( function_exists( $_runnable ) && is_callable( $_runnable ) );

}

just make sure the method isn’t private! Or, instead of passing the object, you could modify it to accept the class name.

Tim January 7, 2011 at 12:06 am | Permalink | Reply

Hi,

Seems like a very nice class, and I’ve tried to implement it into an IRC bot written in PHP, but I can’t get it to work properly without the bot dying. After trying Ricardo’s pipe trick, i got a bit further, well the bot doesn’t die after execution, but doesn’t open the pipe either.

I wanted to try to implement some sort of threading mechanism, because the bot might have to execute some heavy commands every now and then, that is – commands which consumes a great amount of time (i.e. a ping command), which stalls the but while executing – so my thoughts were, launch the command in a new thread, and write back the reponse (when done) to the user/channel – while being able to make the bot do other tasks, while processing.

Any ideas? or is this just not possible?

Thanks,
/Tim

PieterMX January 13, 2011 at 1:48 pm | Permalink | Reply

Nice class, added a few lines to support static functions in objects:

/**
 * Implements threading in PHP
 * 
 * @package 
 * @version 1.0.0 - stable
 * @author Tudor Barbu 
 * @copyright MIT
 */
class Core_Thread {
    const FUNCTION_NOT_CALLABLE     = 10;
    const COULD_NOT_FORK            = 15;
    
    /**
     * possible errors
     *
     * @var array
     */
    private $errors = array(
        Core_Thread::FUNCTION_NOT_CALLABLE   => 'You must specify a valid function name that can be called from the current scope.',
        Core_Thread::COULD_NOT_FORK          => 'pcntl_fork() returned a status of -1. No new process was created',
    );
    
    /**
     * callback for the function that should
     * run as a separate thread
     *
     * @var callback
     */
    protected $runnable;
    protected $object;
    
    /**
     * holds the current process id
     *
     * @var integer
     */
    private $pid;
    
    /**
     * checks if threading is supported by the current
     * PHP configuration
     *
     * @return boolean
     */
    public static function available() {
        $required_functions = array(
            'pcntl_fork',
        );
        
        foreach( $required_functions as $function ) {
            if ( !function_exists( $function ) ) {
                return false;
            }
        }
        
        return true;
    }
    
    /**
     * class constructor - you can pass
     * the callback function as an argument
     *
     * @param callback $_runnable
     */
    public function __construct( $_runnable = null, $_object = null ) {
        if( $_runnable !== null ) {
            $this->setRunnable( $_runnable, $_object );
        }
    }
    
    /**
     * sets the callback
     *
     * @param callback $_runnable
     * @return callback
     */
    public function setRunnable( $_runnable, $_object = null ) {
        if( self::runnableOk( $_runnable, $_object ) ) {
            $this->runnable = $_runnable;
            $this->object = $_object;
        }
        else {
            throw new Core_Exception( $this->getError( Core_Thread::FUNCTION_NOT_CALLABLE ), Core_Thread::FUNCTION_NOT_CALLABLE );
        }
    }
    
    /**
     * gets the callback
     *
     * @return callback
     */
    public function getRunnable()
    {
        if($this->object)
            return array($this->object, $this->runnable);
            
        return $this->runnable ;
    }
    
    /**
     * checks if the callback is ok (the function/method
     * actually exists and is runnable from the current
     * context)
     * 
     * can be called statically
     *
     * @param callback $_runnable
     * @return boolean
     */
    public static function runnableOk( $_runnable, $_object = null ) {
        if($_object !== null)
            return ( method_exists( $_object, $_runnable ) &amp;&amp; is_callable( array($_object, $_runnable ) ) );
        else
            return ( function_exists( $_runnable ) &amp;&amp; is_callable( $_runnable ) );
    }
    
    /**
     * returns the process id (pid) of the simulated thread
     * 
     * @return int
     */
    public function getPid() {
        return $this->pid;
    }
    
    /**
     * checks if the child thread is alive
     *
     * @return boolean
     */
    public function isAlive() {
        $pid = pcntl_waitpid( $this->pid, $status, WNOHANG );
        return ( $pid === 0 );
        
    }
    
    /**
     * starts the thread, all the parameters are 
     * passed to the callback function
     * 
     * @return void
     */
    public function start() {
        $pid = pcntl_fork();
        if( $pid == -1 ) {
            throw new Core_Exception( $this->getError( Core_Thread::COULD_NOT_FORK ), Core_Thread::COULD_NOT_FORK );
        }
        if( $pid ) {
            // parent 
            $this->pid = $pid;
        }
        else {
            // child
            pcntl_signal( SIGTERM, array( $this, 'signalHandler' ) );
            $arguments = func_get_args();
            if ( !empty( $arguments ) ) {
                call_user_func_array( $this->getRunnable(), $arguments );
            }
            else {
                call_user_func( $this->getRunnable() );
            }
            
            exit( 0 );
        }
    }
    
    /**
     * attempts to stop the thread
     * returns true on success and false otherwise
     *
     * @param integer $_signal - SIGKILL/SIGTERM
     * @param boolean $_wait
     */
    public function stop( $_signal = SIGKILL, $_wait = false ) {
        if( $this->isAlive() ) {
            posix_kill( $this->pid, $_signal );
            if( $_wait ) {
                pcntl_waitpid( $this->pid, $status = 0 );
            }
        }
    }
    
    /**
     * alias of stop();
     *
     * @return boolean
     */
    public function kill( $_signal = SIGKILL, $_wait = false ) {
        return $this->stop( $_signal, $_wait );
    }
    
    /**
     * gets the error's message based on
     * its id
     *
     * @param integer $_code
     * @return string
     */
    public function getError( $_code ) {
        if ( isset( $this->errors[$_code] ) ) {
            return $this->errors[$_code];
        }
        else {
            return 'No such error code ' . $_code . '! Quit inventing errors!!!';
        }
    }
    
    /**
     * signal handler
     *
     * @param integer $_signal
     */
    protected function signalHandler( $_signal ) {
        switch( $_signal ) {
            case SIGTERM:
                exit( 0 );
            break;
        }
    }
}

// EOF

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/**

* Implements threading in PHP

* @package

* @version 1.0.0 - stable

* @author Tudor Barbu

* @copyright MIT

class Core_Thread {

const FUNCTION_NOT_CALLABLE = 10;

const COULD_NOT_FORK = 15;

/**

* possible errors

* @var array

private $errors = array(

Core_Thread::FUNCTION_NOT_CALLABLE => 'You must specify a valid function name that can be called from the current scope.',

Core_Thread::COULD_NOT_FORK => 'pcntl_fork() returned a status of -1. No new process was created',

);

/**

* callback for the function that should

* run as a separate thread

* @var callback

protected $runnable;

protected $object;

/**

* holds the current process id

* @var integer

private $pid;

/**

* checks if threading is supported by the current

* PHP configuration

* @return boolean

public static function available() {

$required_functions = array(

'pcntl_fork',

);

foreach( $required_functions as $function ) {

if ( !function_exists( $function ) ) {

return false;

}

return true;

}

/**

* class constructor - you can pass

* the callback function as an argument

* @param callback $_runnable

public function __construct( $_runnable = null, $_object = null ) {

if( $_runnable !== null ) {

$this->setRunnable( $_runnable, $_object );

}

/**

* sets the callback

* @param callback $_runnable

* @return callback

public function setRunnable( $_runnable, $_object = null ) {

if( self::runnableOk( $_runnable, $_object ) ) {

$this->runnable = $_runnable;

$this->object = $_object;

}

else {

throw new Core_Exception( $this->getError( Core_Thread::FUNCTION_NOT_CALLABLE ), Core_Thread::FUNCTION_NOT_CALLABLE );

}

/**

* gets the callback

* @return callback

public function getRunnable()

{

if($this->object)

return array($this->object, $this->runnable);

return $this->runnable ;

}

/**

* checks if the callback is ok (the function/method

* actually exists and is runnable from the current

* context)

* can be called statically

* @param callback $_runnable

* @return boolean

public static function runnableOk( $_runnable, $_object = null ) {

if($_object !== null)

return ( method_exists( $_object, $_runnable ) && is_callable( array($_object, $_runnable ) ) );

else

return ( function_exists( $_runnable ) && is_callable( $_runnable ) );

}

/**

* returns the process id (pid) of the simulated thread

* @return int

public function getPid() {

return $this->pid;

}

/**

* checks if the child thread is alive

* @return boolean

public function isAlive() {

$pid = pcntl_waitpid( $this->pid, $status, WNOHANG );

return ( $pid === 0 );

}

/**

* starts the thread, all the parameters are

* passed to the callback function

* @return void

public function start() {

$pid = pcntl_fork();

if( $pid == -1 ) {

throw new Core_Exception( $this->getError( Core_Thread::COULD_NOT_FORK ), Core_Thread::COULD_NOT_FORK );

}

if( $pid ) {

// parent

$this->pid = $pid;

}

else {

// child

pcntl_signal( SIGTERM, array( $this, 'signalHandler' ) );

$arguments = func_get_args();

if ( !empty( $arguments ) ) {

call_user_func_array( $this->getRunnable(), $arguments );

}

else {

call_user_func( $this->getRunnable() );

}

exit( 0 );

}

/**

* attempts to stop the thread

* returns true on success and false otherwise

* @param integer $_signal - SIGKILL/SIGTERM

* @param boolean $_wait

public function stop( $_signal = SIGKILL, $_wait = false ) {

if( $this->isAlive() ) {

posix_kill( $this->pid, $_signal );

if( $_wait ) {

pcntl_waitpid( $this->pid, $status = 0 );

}

/**

* alias of stop();

* @return boolean

public function kill( $_signal = SIGKILL, $_wait = false ) {

return $this->stop( $_signal, $_wait );

}

/**

* gets the error's message based on

* its id

* @param integer $_code

* @return string

public function getError( $_code ) {

if ( isset( $this->errors[$_code] ) ) {

return $this->errors[$_code];

}

else {

return 'No such error code ' . $_code . '! Quit inventing errors!!!';

}

/**

* signal handler

* @param integer $_signal

protected function signalHandler( $_signal ) {

switch( $_signal ) {

case SIGTERM:

exit( 0 );

break;

}

// EOF

Daniel Pötzinger January 16, 2011 at 10:57 pm | Permalink | Reply

Thanks for sharing this! Inspired by your work I published Threadi today.
@see
http://www.typo3-media.com/blog/multithreating-in-php.html
https://github.com/danielpoe/Threadi
Tudor January 17, 2011 at 12:13 pm | Permalink | Reply

Thanks mate!
Tudor January 17, 2011 at 1:10 pm | Permalink | Reply

Make sure that the pnctl library is installed http://www.php.net/manual/en/book.pcntl.php . I think it’s in the repositories.
mr_mojtaba January 17, 2011 at 12:14 pm | Permalink | Reply

Hi .
I want to use this class in my php code in Ubuntu. but i dont know why it not worked here.
When i run the project:

PHP

if (Thread::available()) { die( 'Threads not supported' ); }

1
2
3

if (Thread::available()) {
die( 'Threads not supported' );
}

This message is shown:
Threads not supported
How can i solve this problem?
mr_mojtaba January 17, 2011 at 2:30 pm | Permalink | Reply

how can i check the pnctl library is installed? Please describe me what do i do to use this class?
Do i use this class(Thread.php) in windws os?
Thanks
mr_mojtaba January 17, 2011 at 2:36 pm | Permalink | Reply

I need multithreading to do some work.Please help me how i can use this class. I write the frist example of this page, but i dont have the problem: ‘Threads not supported’
How can i check pnctl library is installed? How can i?
With Regards.Mojtaba
Tudor January 17, 2011 at 3:56 pm | Permalink | Reply

If it fails with that message, then the library is not installed. I just posted a link in the previous comment to the PHP manual’s section on the pnctl. Read it, install pnctl and it will work…
mr_mojtaba January 18, 2011 at 10:05 am | Permalink | Reply

Thanks very much
mr_mojtaba January 18, 2011 at 11:29 am | Permalink | Reply

I have a question about using threading in php:
I need to check some conditions in my code and if the conditions were true then insert some information to mysql database and redirect the user to other pages. I dont like the user wait so that the informations is recorded to database and then redirect to other pages. Do i can insert information to my database as threading?
If i use this code at the end of my code: While(t1->isAlive()){}…
Then the user should be waiting so that transaction is compeleted and then redirect. So How can i solve this problem?
With Regards.Mojtaba
Tudor January 18, 2011 at 12:41 pm | Permalink | Reply

Writing input to the db takes very little time and you really shouldn’t worry about that. This was only used in a CLI environment so I don’t know its exact behavior under Apache or whatever server you might be using.
Diego January 26, 2011 at 7:26 pm | Permalink | Reply

Hi Tudor, greetings from Ecuador…. I’ve tried your code sending simple parameters to start function (integer and string values) but if I use complex objects I cannot reach functions from my nested variable in the object…. I’m not sure if it is clear…

Thanks so much in advance for the help you could provide me…
Tudor January 26, 2011 at 7:31 pm | Permalink | Reply

Can you post some code?
Marines MUD – W pogoni za RAMem March 12, 2011 at 5:30 pm | Permalink

[…] już szczęśliwym posiadaczem ubuntu, nie stanowi to żadnego problemu. Znalazłem też w sieci fajną klasę, która umożliwia czytelniejszą obsługę wątków w obiektowym stylu. Dzięki tej klasie obsługa wątków jest dziecinnie prosta. Autor zamieścił przykłady jej […]
Kailash April 19, 2011 at 2:50 am | Permalink | Reply

hi Tudo,

I need urgent help in this. I am trying to use your thread.php ro read multiple file but when i call processImage function then it does not come back to main function. Its not going to second loop to read files. Just hangs there itself.

CAn you guide me.

Thanks,
Lea Hayes April 22, 2011 at 12:41 am | Permalink | Reply

Hello Tudor,

What benefits are there to emulating multi-threading in PHP?

Don’t get me wrong, you have come up with a working thread emulation, but what does it actually achieve?

The emulation will incur overhead, but the “threads” will not be assigned to separate processors by the OS. If anything using emulated threads is only going to slow an application down (as opposed to boosting performance).

Cheers,
Tudor April 22, 2011 at 5:35 pm | Permalink | Reply

Dude…seriously!!! Do some reading…
Prozessorauslastung fällt während Skript läuft (unter Ubuntu) - php.de April 27, 2011 at 5:46 pm | Permalink

[…] die skripten multithreaded laufen lasse: hierbei verwende ich einen wrapper für pcntl_fork() (vgl.HIER). das skript erzeugt damit für die ersten 5-10 sekunden vollast auf allen 8 threads (oder sovielen […]
How To “Find And Replace” Words In Multiple Files In a Folder : Ranjith Siji – Programming the Web May 1, 2011 at 6:19 pm | Permalink

[…] via their port numbers (baibhavsingh.wordpress.com)You’ve Been Hacked! (famousbloggers.net)Thread class for multithreading in PHP (motane.lu)How do I increase upload file limit from 2MB to 10MB under Apache 2 UNIX / Linux web […]
Asynchrone Threads in PHP - php.de May 17, 2011 at 10:11 pm | Permalink

[…] danke für den Hinweis. War nur durch das drauf gekommen -> Multithreading PHP Script läuft jetzt auch ganz gut ohne das ganze, aber kurze Frage noch. Wird bei PHP-Code: […]
Jack June 7, 2011 at 10:41 am | Permalink | Reply

Hello,
I just needed a help regarding multithreading in php.So i visited it.
I follow up the source code of multithreading.but in the source m having an error.
[code lang=”php” 1=”[/code” language=”Thread::available()”][/code]
Im having problem in the above line.Can anyone help me out ?

Thanx
O Senhor do PHP: A Irmandade dos Scripts | LordFokas.com – Blog June 25, 2011 at 4:26 pm | Permalink

[…] Outra coisa brutal que me apercebi, é que dá para fazer MultiThreading com PHP, através de uma classe implementada por um individuo cujo nickname é Tudor. Podem aceder ao seu blog e ter acesso a mais especificações sobre a classe Thread() aqui: http://blog.motane.lu/2009/01/02/multithreading-in-php/ […]
cojack July 7, 2011 at 10:53 am | Permalink | Reply

Hello,
Tudor do you have any idea how to create a shared memory between forks? Im realy newbie in this topic 😉

Regards,
cojack.

Gdhami July 21, 2011 at 2:49 pm | Permalink | Reply

Thanks for the code, much appreciated!

I’ve been trying to run a modified version of the 2nd example on my box, it works, but somewhere after executing the threads it stops if I enable the sleep(1); call *or* if I use this line

    while( !empty($threads) )

1	while( !empty($threads) )

Changing while to if fix the problem but well the logic is then broken.

The code is here, I’d be infinitely grateful if you can shed some light on it:

// ================================================ //
$threads = array();

// Create and start threads
for ($i = 1; $i start( $base_name, $file_name, $folder_name, $i );
    $threads[] = array($i - 1 => $thread);
}

// Wait for all the threads to finish
$i = 0;
while( !empty($threads) )
{
    foreach( $threads as $i => &$thread )
    {
        if ( !$thread[$i]->isAlive() ) {
            unset( $threads[$i] ); // die;
            // unset( $thread[$i] );
        }
    }

    // Let the CPU do its work
    sleep(1);
}
// ================================================ //

// ================================================ //

$threads = array();

// Create and start threads

for ($i = 1; $i start( $base_name, $file_name, $folder_name, $i );

$threads[] = array($i - 1 => $thread);

}

// Wait for all the threads to finish

$i = 0;

while( !empty($threads) )

{

foreach( $threads as $i => &$thread )

{

if ( !$thread[$i]->isAlive() ) {

unset( $threads[$i] ); // die;

// unset( $thread[$i] );

}

// Let the CPU do its work

sleep(1);

}

// ================================================ //

Thanks in advance,
Gdhami.

Linkdump #52: ABC PHP. « Tomasz Kowalczyk August 2, 2011 at 9:38 am | Permalink

[…] Multithreading in php. Trochę na temat wielowątkowości w PHP. […]
jost125 August 5, 2011 at 11:36 am | Permalink | Reply

Hi, I was thinking about something very similar, so thanks for saving my time

I have one note, the name is not picked right. Lot of people might be confused, because parallelism via processes is very different than via threads. Threads have shared memory, are run in one process and so on.

So much more suitable name should be Process.

Still thanks for the work!
Bruno October 1, 2011 at 12:10 am | Permalink | Reply

is there a sollution for windows system?
Tudor October 1, 2011 at 6:18 pm | Permalink | Reply

I don’t know! Might be, but I never use windows….
Better Convert pdf to Multiple jpg | Dalibor Sojic October 5, 2011 at 12:53 am | Permalink

[…] By default, PHP has no built-in support for multithreading, but Tudor Barbu has developed multithreading class for PHP. […]
Netbeans Code Templates | The Playabl Blog October 10, 2011 at 4:55 am | Permalink

[…] to make the page load more quickly, I can use a template with the code I found on this PHP Multithreading site. Share […]
sa October 28, 2011 at 6:07 am | Permalink | Reply

is there a sollution for windows system?
Tudor October 29, 2011 at 12:05 pm | Permalink | Reply

Read the comment above yours…
Why is realtime apps for php such a problem? - Quora November 11, 2011 at 6:54 pm | Permalink

[…] level support, there is a guy who created a class which mocks the JAVA Threading here is the link: http://blog.motane.lu/2009/01/02…This answer .Please specify the necessary improvements. Edit Link Text Show answer summary […]
Cosmin December 1, 2011 at 12:48 am | Permalink | Reply

If you are talking about Windows, in most of the cases the discussion involves .NET. Of course..you can achieve multithreading by interoping with Java, C++ etc., but since .NET always come in handy for me, I can recommend you this http://www.facebook.com/note.php?note_id=281965971827784
Suresh December 1, 2011 at 8:30 am | Permalink | Reply

Hi,
Thanks for your information

how to use this for search?
search result will execute same window but override previous one
Cosmin December 2, 2011 at 1:04 am | Permalink | Reply

My post is about achieving multithreading in general, not on a specific case. Of course, you are limited to the single main thread of PHP but which can spawn multiple child threads by interoping, for example, with .net.

You can think of it like this: PHP thread would pass a list of “operations” to be executed on different threads by .net. Instead of having them waiting one for eachother, they could run in parallel. Of course, you can not overcome the limitation of the PHP thread, but there is still a slight gain on performance.
Marian December 9, 2011 at 6:09 pm | Permalink | Reply

Why use the loop to keep things alive?
You can just set the time limit to 0 and only when one thread closes you can check if there are any other working if not exit.
I think you might spare some resources.
I am working a lot with socket listeners built in PHP and Python… so they are never supposed to stop and the PHP version works very neat like that using quite few resources.
anon January 17, 2012 at 6:48 am | Permalink | Reply

what just writing a plugin for sonic daemon?

victor wallin January 27, 2012 at 1:58 am | Permalink | Reply

what do you think about this solution? (Runs on Linux (slackvare) 2.6.27.7)

PHP 5.2.11 (cli) (built: Oct 2 2009 17:30:20)

require_once( "Thread.php" );
if ( function_exists("sem_get") )echo "sem";
   // test to see if threading is available
if( ! Thread::available() ) {
        die( "Threads not supported" );
}
// function to be ran on separate threads
function paralel( $_limit, $_name ,$lock) {
        sem_acquire($lock);
        for ( $index = 0; $index start( 10, 't1',$s1);
$s2 = sem_get(2);
$t2->start( 10, 't2',$s2);
// keep the program running until the threads finish
sem_acquire($s1);
sem_acquire($s2);
/*
while( $t1->isAlive() && t2->isAlive() ) {}//*/

require_once( "Thread.php" );

if ( function_exists("sem_get") )echo "sem";

// test to see if threading is available

if( ! Thread::available() ) {

die( "Threads not supported" );

}

// function to be ran on separate threads

function paralel( $_limit, $_name ,$lock) {

sem_acquire($lock);

for ( $index = 0; $index start( 10, 't1',$s1);

$s2 = sem_get(2);

$t2->start( 10, 't2',$s2);

// keep the program running until the threads finish

sem_acquire($s1);

sem_acquire($s2);

while( $t1->isAlive() && t2->isAlive() ) {}//*/

Tudor January 27, 2012 at 2:26 am | Permalink | Reply

I don’t think your code got pasted right. Use
<pre lang=”php”>…</pre>
to paste properly.
Fizzadar February 25, 2012 at 6:58 pm | Permalink | Reply

Awesome! There’s hardly any good implementations of forking in php available online, and this one is definitely the best!
1. Tudor February 26, 2012 at 12:48 am | Permalink | Reply
  
  Cheers mate!
J. Bruni February 29, 2012 at 5:03 am | Permalink | Reply

Very nice! Thanks for sharing.
Sanjoy March 6, 2012 at 7:45 am | Permalink | Reply

Hi !!!
I am trying to use this above example. I am working in WAMP. When i am running the Parallel-Returnable.php file its shows Fatal error: Class ‘Threadi_Thread_NonThread’ not found

And i want to know how to enable pcntl in WAMP ?
Please help me to solve this.

WIth Thanks & Regards,
Sanjay
http://sanjoyinfoworld.blogspot.in
Tudor March 6, 2012 at 1:17 pm | Permalink | Reply

Sorry mate, I did not write Threadi, so I can’t offer support. You should contact the author, his name is Daniel Pötzinger and he blogs at http://www.typo3-media.com/blog/

However, based on your error – class not found – you didn’t include the library correctly. But if you’re using a windows system, it won’t work as it relies on the pnctl_fork() function to spawn new “threads”. Just read the manual: http://www.php.net/manual/en/book.pcntl.php

Good luck
t.
PHP multithreading through .NET interop « PHP / Zend / www.elcome! March 14, 2012 at 11:48 pm | Permalink

[…] For Unix we have http://www.php.net/manual/en/intro.posix.php and http://www.php.net/manual/en/intro.pcntl.php which are a set of complementary libraries that allows process manipulation operations. Let me repeat that: “process manipulation operations”… since there is nothing mentioned about threading, you can simply put it this way: PHP doesn’t natively support threading in Unix through the libraries mentioned above, instead it supports process forking. As you may already noticed, I used the term of “natively” because you can achive multithreading by interoping with languages like Java, C / C++ or even .NET through Mono. If you may wonder what are the advantages of using threads over processes in general, read this http://www.programmerinterview.com/index.php/operating-systems/thread-vs-process/; in particular, each language can have it’s own mechanisms of dealing with threads. A nice article on “multithreading” in PHP can be found on my comrade’s blog Tudor a.k.a. motanelu http://blog.motane.lu/2009/01/02/multithreading-in-php/. […]
dTrane March 28, 2012 at 11:43 pm | Permalink | Reply

Hello they call me Gabe I love handbags and all kinds of other things as well!

Julio Araya April 17, 2012 at 10:06 pm | Permalink | Reply

Wanna use objects and his methods or static methods?

Step 1: Change the method Thread::runnableOk to this:

public static function runnableOk( $_runnable ) {
    if (is_array($_runnable) && count($_runnable) == 2 ) {
        return method_exists($_runnable[0], $_runnable[1]);
    } 
        return ( function_exists( $_runnable ) && is_callable( $_runnable ) );
}:

public static function runnableOk( $_runnable ) {

if (is_array($_runnable) && count($_runnable) == 2 ) {

return method_exists($_runnable[0], $_runnable[1]);

}

return ( function_exists( $_runnable ) && is_callable( $_runnable ) );

Step 2: Use this code to use you objects

class MyClass {
    // function to be ran on separate threads
    function paralel( $_limit, $_name ) {
        for ( $index = 0; $index < $_limit; $index++ ) {
            echo 'Now running thread ' . $_name . PHP_EOL;
            sleep( 1 );
        }
    }
    
    public static function staticMethod ( $_limit, $_name ) {
        for ( $index = 0; $index < $_limit; $index++ ) {
            echo 'Now running thread static ' . $_name . PHP_EOL;
            sleep( 1 );
        }
    }
}

$m1 = new MyClass();

// create 2 thread objects
$t1 = new Thread( array($m1,'paralel') );
$t2 = new Thread( array('MyClass','staticMethod') );

class MyClass {

// function to be ran on separate threads

function paralel( $_limit, $_name ) {

for ( $index = 0; $index < $_limit; $index++ ) {

echo 'Now running thread ' . $_name . PHP_EOL;

sleep( 1 );

}

public static function staticMethod ( $_limit, $_name ) {

for ( $index = 0; $index < $_limit; $index++ ) {

echo 'Now running thread static ' . $_name . PHP_EOL;

sleep( 1 );

}

$m1 = new MyClass();

// create 2 thread objects

$t1 = new Thread( array($m1,'paralel') );

$t2 = new Thread( array('MyClass','staticMethod') );

😉

[PHP] Listener April 21, 2012 at 4:59 pm | Permalink

[…] […]
Pointless Ramblings April 27, 2012 at 2:22 am | Permalink

[…] An example daemon is listed below, the class requires the PHP pcntl extension (*nix only) & Tudor Barbu’s excellent Thread class → […]
Damian May 21, 2012 at 1:16 am | Permalink | Reply

I did some of php coding for electriccars4kids.org
Thank you for sharing!
Lorin June 4, 2012 at 12:53 pm | Permalink | Reply

Regarding threading and MySQL (or probably any database server), here are my findings which might help someone else. Generally, launching a new thread “duplicates” all the variables and memory contents of the parent and your child starts with all of it as “baggage”. This includes your current connection to MySQL. As long as your parent (or a second child) doesn’t use that connection, you can use it from your child without any problems. If you have multiple children using the database, each child should open it’s own connection (that kind of makes sense).

However, PHP screws you as soon as your first child ends. As we know, PHP automatically closes connections to MySQL once a script (e.g. your child) ends. This unfortunately includes the connection the child inherited initially from the parent. This means that as soon as one of your child processes has ended, your parent process will have to reconnect to MySQL in order to do anything with the database – or you will get the “MySQL has gone away” error.

In order to keep connections clearly assigned to each thread, I recommend to:
– open one new connection per child
– store the connection resource in a variable and always the identifier for any mysql_* commands. If you use mysqli, use the object oriented aproach and create a new mysqli-object for each thread.
– remember that your parent’s mysql connection will be broken as soon as the first child process has ended. your parent will need to reconnect to MySQL.
Max July 12, 2012 at 9:09 pm | Permalink | Reply

I like you simple implementation, I see many threads in my task manager after running your script. I found on Git hub similar project which work better for me. https://github.com/kulikov/php-threads-manager
Chey August 17, 2012 at 6:58 pm | Permalink | Reply

For those interested in parallel processing you can check out Gearman. Works with PHP.

http://gearman.org/
Simon September 8, 2012 at 9:33 am | Permalink | Reply

Hi Tudor
This is a great function you have build. It’s easy to use and work very well.
Is there a build-in function to limit the number processes that runs at the same time? Or have you thought about building it in. I have for example perhaps 500000 loops through some data, that I want to spread out on multi processes, but of course I suppose it will not be good to start 50000 processes at the same time?! Or is there something build into PHP that ensures it doesn’t start to many at the same time?
No Threading In Shared Servers « The Playabl Blog September 10, 2012 at 5:53 am | Permalink

[…] have the cheapest plan in Dreamhost, which is the Shared Server plan. I tried testing Tudor Barbu's Thread class to see if I could get my site to multi-thread in order to produce pages as quickly as […]
Php script issue, syntax error | question code September 24, 2012 at 6:32 am | Permalink

[…] this one specific threading system i found in php, but it gives a error on index = 0;, any ideas? http://blog.motane.lu/2009/01/02/multithreading-in-php/ any help is appreciated. and i attached the link to the thread script of course, and thats about […]

Gerben Wijnja September 24, 2012 at 10:45 pm | Permalink | Reply

Hmm, I expected my code to be recognized, but it’s not syntax highlighted. Can’t find any pointers on how to post code, so here goes another try with [ code ] tags.

I made some code style improvements:

Made all the code PHP CodeSniffer compatible.
Fixed return type of kill() from ‘boolean’ to ‘void’. Stop() returns void, so kill() will also return void.
Removed underscores from local variables. Only private class variables should be prefixed with an underscore.
Changed function name available() to isAvailable() – function names should always start with a verb.
Changed function name runnableOk() to isRunnableOk() – same reason
Changed function name signalHandler() to handleSignal() – same reason

/**
 * Implements threading in PHP
 *
 * PHP version 5
 *
 * @category  Threading
 * @package   None
 * @author    Tudor Barbu <miau@motane.lu>
 * @copyright 2009 MIT
 * @license   http://en.wikipedia.org/wiki/MIT_License MIT License
 * @link      http://blog.motane.lu/2009/01/02/multithreading-in-php/
 */

/**
 * Thread class
 *
 * @category  Threading
 * @package   None
 * @author    Tudor Barbu <miau@motane.lu>
 * @copyright 2009 MIT
 * @license   http://en.wikipedia.org/wiki/MIT_License MIT License
 * @link      http://blog.motane.lu/2009/01/02/multithreading-in-php/
 */

class Thread
{
    const FUNCTION_NOT_CALLABLE = 10;
    const COULD_NOT_FORK        = 15;

    /**
     * Possible errors
     *
     * @var array
     */
    private $_errors = array(
        Thread::FUNCTION_NOT_CALLABLE =>
            'You must specify a valid function name that can be called '.
            'from the current scope.',
        Thread::COULD_NOT_FORK        =>
            'pcntl_fork() returned a status of -1. No new process was created'
    );

    /**
     * Callback for the function that should run as a separate thread
     *
     * @var callback
     */
    protected $runnable;


    /**
     * Holds the current process id
     *
     * @var integer
     */
    private $_pid;

    /**
     * Checks if threading is supported by the current PHP configuration
     *
     * @return boolean
     */
    public static function isAvailable()
    {
        $required_functions = array(
            'pcntl_fork',
        );

        foreach ( $required_functions as $function ) {
            if ( !function_exists($function) ) {
                return false;
            }
        }

        return true;
    }

    /**
     * Class constructor - you can pass
     * the callback function as an argument
     *
     * @param callback $runnable Callback reference
     */
    public function __construct( $runnable = null )
    {
        if ( $runnable !== null ) {
            $this->setRunnable($runnable);
        }
    }

    /**
     * Sets the callback
     *
     * @param callback $runnable Callback reference
     *
     * @return callback
     */
    public function setRunnable( $runnable )
    {
        if ( self::isRunnableOk($runnable) ) {
            $this->runnable = $runnable;
        } else {
            throw new Exception(
                $this->getError(Thread::FUNCTION_NOT_CALLABLE),
                Thread::FUNCTION_NOT_CALLABLE
            );
        }
    }

    /**
     * Gets the callback
     *
     * @return callback
     */
    public function getRunnable()
    {
        return $this->runnable;
    }

    /**
     * Checks if the callback is ok (the function/method
     * actually exists and is runnable from the current
     * context)
     *
     * can be called statically
     *
     * @param callback $runnable Callback
     *
     * @return boolean
     */
    public static function isRunnableOk( $runnable )
    {
        return ( function_exists($runnable) && is_callable($runnable) );
    }

    /**
     * Returns the process id (pid) of the simulated thread
     *
     * @return int
     */
    public function getPid()
    {
        return $this->_pid;
    }

    /**
     * Checks if the child thread is alive
     *
     * @return boolean
     */
    public function isAlive()
    {
        $pid = pcntl_waitpid($this->_pid, $status, WNOHANG);
        return ( $pid === 0 );

    }

    /**
     * Starts the thread, all the parameters are
     * passed to the callback function
     *
     * @return void
     */
    public function start()
    {
        $pid = @pcntl_fork();
        if ( $pid == -1 ) {
            throw new Exception(
                $this->getError(Thread::COULD_NOT_FORK),
                Thread::COULD_NOT_FORK
            );
        }
        if ( $pid ) {
            // parent
            $this->_pid = $pid;
        } else {
            // child
            pcntl_signal(SIGTERM, array( $this, 'handleSignal' ));
            $arguments = func_get_args();
            if ( !empty($arguments) ) {
                call_user_func_array($this->runnable, $arguments);
            } else {
                call_user_func($this->runnable);
            }

            exit( 0 );
        }
    }

    /**
     * Attempts to stop the thread
     * returns true on success and false otherwise
     *
     * @param integer $signal SIGKILL or SIGTERM
     * @param boolean $wait   Wait until child has exited
     *
     * @return void
     */
    public function stop( $signal = SIGKILL, $wait = false )
    {
        if ( $this->isAlive() ) {
            posix_kill($this->_pid, $signal);
            if ( $wait ) {
                pcntl_waitpid($this->_pid, $status = 0);
            }
        }
    }

    /**
     * Alias of stop();
     *
     * @param integer $signal SIGKILL or SIGTERM
     * @param boolean $wait   Wait until child has exited
     *
     * @return void
     */
    public function kill( $signal = SIGKILL, $wait = false )
    {
        return $this->stop($signal, $wait);
    }

    /**
     * Gets the error's message based on its id
     *
     * @param integer $code The error code
     *
     * @return string
     */
    public function getError( $code )
    {
        if ( isset( $this->_errors[$code] ) ) {
            return $this->_errors[$code];
        } else {
            return "No such error code $code ! Quit inventing errors!!!";
        }
    }

    /**
     * Signal handler
     *
     * @param integer $signal Signal
     *
     * @return void
     */
    protected function handleSignal( $signal )
    {
        switch( $signal ) {
        case SIGTERM:
            exit( 0 );
            break;
        }
    }
}

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/**

* Implements threading in PHP

* PHP version 5

* @category Threading

* @package None

* @author Tudor Barbu <miau@motane.lu>

* @license http://en.wikipedia.org/wiki/MIT_License MIT License

* @link http://blog.motane.lu/2009/01/02/multithreading-in-php/

/**

* Thread class

* @category Threading

* @package None

* @author Tudor Barbu <miau@motane.lu>

* @license http://en.wikipedia.org/wiki/MIT_License MIT License

* @link http://blog.motane.lu/2009/01/02/multithreading-in-php/

class Thread

{

const FUNCTION_NOT_CALLABLE = 10;

const COULD_NOT_FORK = 15;

/**

* Possible errors

* @var array

private $_errors = array(

Thread::FUNCTION_NOT_CALLABLE =>

'You must specify a valid function name that can be called '.

'from the current scope.',

Thread::COULD_NOT_FORK =>

'pcntl_fork() returned a status of -1. No new process was created'

);

/**

* Callback for the function that should run as a separate thread

* @var callback

protected $runnable;

/**

* Holds the current process id

* @var integer

private $_pid;

/**

* Checks if threading is supported by the current PHP configuration

* @return boolean

public static function isAvailable()

{

$required_functions = array(

'pcntl_fork',

);

foreach ( $required_functions as $function ) {

if ( !function_exists($function) ) {

return false;

}

return true;

}

/**

* Class constructor - you can pass

* the callback function as an argument

* @param callback $runnable Callback reference

public function __construct( $runnable = null )

{

if ( $runnable !== null ) {

$this->setRunnable($runnable);

}

/**

* Sets the callback

* @param callback $runnable Callback reference

* @return callback

public function setRunnable( $runnable )

{

if ( self::isRunnableOk($runnable) ) {

$this->runnable = $runnable;

} else {

throw new Exception(

$this->getError(Thread::FUNCTION_NOT_CALLABLE),

Thread::FUNCTION_NOT_CALLABLE

);

}

/**

* Gets the callback

* @return callback

public function getRunnable()

{

return $this->runnable;

}

/**

* Checks if the callback is ok (the function/method

* actually exists and is runnable from the current

* context)

* can be called statically

* @param callback $runnable Callback

* @return boolean

public static function isRunnableOk( $runnable )

{

return ( function_exists($runnable) && is_callable($runnable) );

}

/**

* Returns the process id (pid) of the simulated thread

* @return int

public function getPid()

{

return $this->_pid;

}

/**

* Checks if the child thread is alive

* @return boolean

public function isAlive()

{

$pid = pcntl_waitpid($this->_pid, $status, WNOHANG);

return ( $pid === 0 );

}

/**

* Starts the thread, all the parameters are

* passed to the callback function

* @return void

public function start()

{

$pid = @pcntl_fork();

if ( $pid == -1 ) {

throw new Exception(

$this->getError(Thread::COULD_NOT_FORK),

Thread::COULD_NOT_FORK

);

}

if ( $pid ) {

// parent

$this->_pid = $pid;

} else {

// child

pcntl_signal(SIGTERM, array( $this, 'handleSignal' ));

$arguments = func_get_args();

if ( !empty($arguments) ) {

call_user_func_array($this->runnable, $arguments);

} else {

call_user_func($this->runnable);

}

exit( 0 );

}

/**

* Attempts to stop the thread

* returns true on success and false otherwise

* @param integer $signal SIGKILL or SIGTERM

* @param boolean $wait Wait until child has exited

* @return void

public function stop( $signal = SIGKILL, $wait = false )

{

if ( $this->isAlive() ) {

posix_kill($this->_pid, $signal);

if ( $wait ) {

pcntl_waitpid($this->_pid, $status = 0);

}

/**

* Alias of stop();

* @param integer $signal SIGKILL or SIGTERM

* @param boolean $wait Wait until child has exited

* @return void

public function kill( $signal = SIGKILL, $wait = false )

{

return $this->stop($signal, $wait);

}

/**

* Gets the error's message based on its id

* @param integer $code The error code

* @return string

public function getError( $code )

{

if ( isset( $this->_errors[$code] ) ) {

return $this->_errors[$code];

} else {

return "No such error code $code ! Quit inventing errors!!!";

}

/**

* Signal handler

* @param integer $signal Signal

* @return void

protected function handleSignal( $signal )

{

switch( $signal ) {

case SIGTERM:

exit( 0 );

break;

}

Tudor October 1, 2012 at 6:30 pm | Permalink | Reply

Cheers mate! That was the coding standard of the company I was working for at the time. We weren’t using Zend’s coding standard!
redknight101 October 11, 2012 at 9:49 am | Permalink | Reply

How can I include max number of process?
smith October 18, 2012 at 4:06 pm | Permalink | Reply

Hi Tubo,

Your code is very clear.. i tried the example in shared hosting.
This script only runs the first thread…
Can you help me how to do this??
Zizaco October 19, 2012 at 8:46 am | Permalink | Reply

Amazing class man. Thank you! I will post an article about it in my blog soon.
I’ve done some “pipeing” using Memcached. Now this:

PHP

$t1 = new Thread( 'processing' ); $t1->start(); while( $t1->isAlive() ) {} echo "Thread return: ".$t1->getReturn();

1
2
3

$t1 = new Thread( 'processing' ); $t1->start();
while( $t1->isAlive() ) {}
echo "Thread return: ".$t1->getReturn();

…works like a charm. (:
Same PHP script is showing different output in browser than when it’s run from command line December 30, 2012 at 9:17 am | Permalink

[…] “database.php” & “Thread.php” (Thread.php has been downloaded from here). database.php does some trivial tasks after connecting to a remote MondoDb database. Here’s […]
Same PHP script is showing different output in browser than when it#39;s run from command lineCode and Programming January 30, 2013 at 1:01 pm | Permalink

[…] “database.php” & “Thread.php” (Thread.php has been downloaded from here). database.php does some trivial tasks after connecting to a remote MondoDb database. Here’s […]
Ricardo Fontanelli February 7, 2013 at 5:05 pm | Permalink | Reply

Hi, thanks for sharing, when I used this class (by web browser), the response return ‘Content-type: text/html’ in my browser. Is it some Apache configuration?
PHP MULTITHREADING ( PHP MULTIHILOS ) | TusCodes.com February 18, 2013 at 7:37 pm | Permalink

[…] clase Thread NO la desarrollamos nosotros, el crédito es de Tudor, pero le hicimos unas modificaciones para que funcionara con clases, solo pasándole como parametro […]
Catalin May 31, 2013 at 1:22 pm | Permalink | Reply

Hi,

Nice job with fork, but i would like to know if creating a c++ extension for php and using c++ threads is not a better approach.
As far as i know fork does not create genuine threads.

Thx
ranaji July 10, 2013 at 7:01 am | Permalink | Reply

hi,
i have an idea to use it on windows also you can leran it from below link.
mutithreading in php .
thanks.
Is there a set time out equivalent in php? - PHP Solutions - Developers Q & A August 28, 2013 at 5:16 am | Permalink

[…] need to start new thread, try this http://blog.motane.lu/2009/01/02/multithreading-in-php/ This entry was posted in PHP on June 26, 2011 by […]
Php multithreading (Php multihilos) | TusCodes November 6, 2013 at 8:32 pm | Permalink

[…] clase Thread NO la desarrollamos nosotros, el crédito es de Tudor, pero le hicimos unas modificaciones para que funcionara con clases, solo pasándole como parametro […]
a January 31, 2014 at 12:00 pm | Permalink | Reply

i cant find threads.php file, can someone share asap?
Mike January 31, 2014 at 6:31 pm | Permalink | Reply

Just FYI.. The link to Thread.php is broken. I was able to copy it from a commentor but figured you might want to fix the link.

Cheers!
a February 5, 2014 at 9:10 am | Permalink | Reply

can u upload a copy of it. so tht i can download, pls
Dd February 22, 2014 at 11:39 pm | Permalink | Reply

Cannot download! Clicking on the link redirects to a page with only plain text: “No input file specified.”
soumik March 25, 2014 at 8:35 am | Permalink | Reply

thread.php not available in the following link ‘http://downloads.motane.lu/Thread.php’
Manoj May 28, 2014 at 3:15 pm | Permalink | Reply

Hey,
I tried to download ‘Thread.php’, but it’s giving me message in new page :- ‘No input file specified.’. Can anybody help?
Vinayaka June 3, 2014 at 8:42 am | Permalink | Reply

I am not able to downlod Threads class

http://downloads.motane.lu/Thread.php
isbkch June 12, 2014 at 11:50 pm | Permalink | Reply

Link is dead, is there some chance you can fix it ?
Tudor July 27, 2014 at 11:07 am | Permalink | Reply

I have updated the link, it points to a github repository. Sorry about the inconvenience!
Jason September 12, 2014 at 3:31 am | Permalink | Reply

For some odd reason I have a legacy PHP script that uses this on PHP 5.2 without any problems but on PHP 5.5 the children that are forked hang and require a kill -9 to get rid of. Does this work on PHP 5.5 or do I need to look at the other script as the problem for the hang?
Farhan ISlam January 4, 2015 at 9:20 pm | Permalink | Reply

Not sure if this helps or not, but I am looking for running a multithread application inside windows.

Any alternative for windows based PHP program?
Tudor January 6, 2015 at 10:11 am | Permalink | Reply

Sorry mate, I never use windows, so…
Mu August 3, 2015 at 12:46 am | Permalink | Reply

Your test code above contains HTML errors,

EG:

// start them
$t1->start( 10, ‘t1’ );
$t2->start( 10, ‘t2’ );

is that supported to be:

$t1 = start( 10, ‘t1’ );
$t2 = start( 10, ‘t2’ );

ITs all over the place
Mu August 3, 2015 at 12:47 am | Permalink | Reply

ohh when I paste it here it fixed it self up.
require_once( ‘Thread.php’ );

// test to see if threading is available
if( ! Thread::available() ) {
die( ‘Threads not supported’ );
}

// function to be ran on separate threads
function paralel( $_limit, $_name ) {
for ( $index = 0; $index < $_limit; $index++ ) {
echo ‘Now running thread ‘ . $_name . PHP_EOL;
sleep( 1 );
}
}

// create 2 thread objects
$t1 = new Thread( ‘paralel’ );
$t2 = new Thread( ‘paralel’ );

// start them
$t1->start( 10, ‘t1’ );
$t2->start( 10, ‘t2’ );

// keep the program running until the threads finish
while( $t1->isAlive() && $t2->isAlive() ) {
sleep(1);
}
Tudor August 3, 2015 at 11:04 pm | Permalink | Reply

Use pre tags to display code, as described on this page – http://tudorbarbu.ninja/the-blog/
Harpreet Bhatia July 14, 2016 at 3:00 pm | Permalink | Reply

Hi,
First, thats a very nice code there. Really useful.
Second, I am a bit concerned. I am on Ubuntu. while testing your code. i was also check current running processes using `htop.
Now i found out that 2 new processes were created. but not killed.
Why weren’t the processes killed? What should we do?

Multithreading in php

Download Thread.php

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