Is there a realistic way of implementing a multi-threaded model in PHP whether truly, or just simulating it. Some time back it was suggested that you could force the operating system to load another instance of the PHP executable and handle other simultaneous processes.
The problem with this is that when the PHP code finished executing the PHP instance remains in memory because there is no way to kill it from within PHP. So if you are simulating several threads you can imagine whats going to happen. So I am still looking for a way multi-threading can be done or simulated effectively from within PHP. Any ideas?
Yes you can do multi-threading in PHP with pthreads
From the PHP documentation:
pthreads is an object-orientated API that provides all of the tools needed for multi-threading in PHP. PHP applications can create, read, write, execute and synchronize with Threads, Workers and Threaded objects.
Warning: The pthreads extension cannot be used in a web server environment. Threading in PHP should therefore remain to CLI-based applications only.
Simple Test
#!/usr/bin/php
<?php
class AsyncOperation extends Thread {
public function __construct($arg) {
$this->arg = $arg;
}
public function run() {
if ($this->arg) {
$sleep = mt_rand(1, 10);
printf('%s: %s -start -sleeps %d' . "\n", date("g:i:sa"), $this->arg, $sleep);
sleep($sleep);
printf('%s: %s -finish' . "\n", date("g:i:sa"), $this->arg);
}
}
}
// Create a array
$stack = array();
//Initiate Multiple Thread
foreach ( range("A", "D") as $i ) {
$stack[] = new AsyncOperation($i);
}
// Start The Threads
foreach ( $stack as $t ) {
$t->start();
}
?>
First Run
12:00:06pm: A -start -sleeps 5
12:00:06pm: B -start -sleeps 3
12:00:06pm: C -start -sleeps 10
12:00:06pm: D -start -sleeps 2
12:00:08pm: D -finish
12:00:09pm: B -finish
12:00:11pm: A -finish
12:00:16pm: C -finish
Second Run
12:01:36pm: A -start -sleeps 6
12:01:36pm: B -start -sleeps 1
12:01:36pm: C -start -sleeps 2
12:01:36pm: D -start -sleeps 1
12:01:37pm: B -finish
12:01:37pm: D -finish
12:01:38pm: C -finish
12:01:42pm: A -finish
Real World Example
error_reporting(E_ALL);
class AsyncWebRequest extends Thread {
public $url;
public $data;
public function __construct($url) {
$this->url = $url;
}
public function run() {
if (($url = $this->url)) {
/*
* If a large amount of data is being requested, you might want to
* fsockopen and read using usleep in between reads
*/
$this->data = file_get_contents($url);
} else
printf("Thread #%lu was not provided a URL\n", $this->getThreadId());
}
}
$t = microtime(true);
$g = new AsyncWebRequest(sprintf("http://www.google.com/?q=%s", rand() * 10));
/* starting synchronization */
if ($g->start()) {
printf("Request took %f seconds to start ", microtime(true) - $t);
while ( $g->isRunning() ) {
echo ".";
usleep(100);
}
if ($g->join()) {
printf(" and %f seconds to finish receiving %d bytes\n", microtime(true) - $t, strlen($g->data));
} else
printf(" and %f seconds to finish, request failed\n", microtime(true) - $t);
}
why don't you use popen?
for ($i=0; $i<10; $i++) {
// open ten processes
for ($j=0; $j<10; $j++) {
$pipe[$j] = popen('script2.php', 'w');
}
// wait for them to finish
for ($j=0; $j<10; ++$j) {
pclose($pipe[$j]);
}
}
Threading isn't available in stock PHP, but concurrent programming is possible by using HTTP requests as asynchronous calls.
With the curl's timeout setting set to 1 and using the same session_id for the processes you want to be associated with each other, you can communicate with session variables as in my example below. With this method you can even close your browser and the concurrent process still exists on the server.
Don't forget to verify the correct session ID like this:
http://localhost/test/verifysession.php?sessionid=[the correct id]
$request = "http://localhost/test/process1.php?sessionid=".$_REQUEST["PHPSESSID"];
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $request);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_TIMEOUT, 1);
curl_exec($ch);
curl_close($ch);
echo $_REQUEST["PHPSESSID"];
set_time_limit(0);
if ($_REQUEST["sessionid"])
session_id($_REQUEST["sessionid"]);
function checkclose()
{
global $_SESSION;
if ($_SESSION["closesession"])
{
unset($_SESSION["closesession"]);
die();
}
}
while(!$close)
{
session_start();
$_SESSION["test"] = rand();
checkclose();
session_write_close();
sleep(5);
}
if ($_REQUEST["sessionid"])
session_id($_REQUEST["sessionid"]);
session_start();
var_dump($_SESSION);
if ($_REQUEST["sessionid"])
session_id($_REQUEST["sessionid"]);
session_start();
$_SESSION["closesession"] = true;
var_dump($_SESSION);
While you can't thread, you do have some degree of process control in php. The two function sets that are useful here are:
Process control functions http://www.php.net/manual/en/ref.pcntl.php
POSIX functions http://www.php.net/manual/en/ref.posix.php
You could fork your process with pcntl_fork - returning the PID of the child. Then you can use posix_kill to despose of that PID.
That said, if you kill a parent process a signal should be sent to the child process telling it to die. If php itself isn't recognising this you could register a function to manage it and do a clean exit using pcntl_signal.
I know this is an old question but for people searching, there is a PECL extension written in C that gives PHP multi-threading capability now, it's located here https://github.com/krakjoe/pthreads
using threads is made possible by the pthreads PECL extension
You could simulate threading. PHP can run background processes via popen (or proc_open). Those processes can be communicated with via stdin and stdout. Of course those processes can themselves be a php program. That is probably as close as you'll get.
You can use exec() to run a command line script (such as command line php), and if you pipe the output to a file then your script won't wait for the command to finish.
I can't quite remember the php CLI syntax, but you'd want something like:
exec("/path/to/php -f '/path/to/file.php' | '/path/to/output.txt'");
I think quite a few shared hosting servers have exec() disabled by default for security reasons, but might be worth a try.
Depending on what you're trying to do you could also use curl_multi to achieve it.
I know this is way old, but you could look at http://phpthreadlib.sourceforge.net/
It supports bi-directional inter-thread communication and also has builtin protections for killing off child threads (preventing orphans).
You can have option of:
How about pcntl_fork?
check our the manual page for examples: PHP pcntl_fork
pcntl_fork won't work in a web server environment if it has safe mode turned on. In this case, it will only work in the CLI version of PHP.
The Thread class is available since PECL pthreads ≥ 2.0.0.
As of the writing of my current comment, I don't know about the PHP threads. I came to look for the answer here myself, but one workaround is that the PHP program that receives the request from the web server delegates the whole answer formulation to a console application that stores its output, the answer to the request, to a binary file and the PHP program that launched the console application returns that binary file byte-by-byte as the answer to the received request. The console application can be written in any programming language that runs on the server, including those that have proper threading support, including C++ programs that use OpenMP.
One unreliable, dirty, trick is to use PHP for executing a console application, "uname",
uname -a
and print the output of that console command to the HTML output to find out the exact version of the server software. Then install the exact same version of the software to a VirtualBox instance, compile/assemble whatever fully self-contained, preferably static, binaries that one wants and then upload those to the server. From that point onwards the PHP application can use those binaries in the role of the console application that has proper multi-threading. It's a dirty, unreliable, workaround to a situation, when the server administrator has not installed all needed programming language implementations to the server. The thing to watch out for is that at every request that the PHP application receives the console application(s) terminates/exit/get_killed.
As to what the hosting service administrators think of such server usage patterns, I guess it boils down to culture. In Northern Europe the service provider HAS TO DELIVER WHAT WAS ADVERTISED and if execution of console commands was allowed and uploading of non-malware files was allowed and the service provider has a right to kill any server process after a few minutes or even after 30 seconds, then the hosting service administrators lack any arguments for forming a proper complaint. In United States and Western Europe the situation/culture is very different and I believe that there's a great chance that in U.S. and/or Western Europe the hosting service provider will refuse to serve hosting service clients that use the above described trick. That's just my guess, given my personal experience with U.S. hosting services and given what I have heard from others about Western European hosting services. As of the writing of my current comment(2018_09_01) I do not know anything about the cultural norms of the Southern-European hosting service providers, Southern-European network administrators.
May be I missed something but exec did not worked as asynchronous for me in windows environment i used following in windows and it worked like charm ;)
$script_exec = "c:/php/php.exe c:/path/my_ascyn_script.php";
pclose(popen("start /B ". $script_exec, "r"));
Multithreading means performing multiple tasks or processes simultaneously, we can achieve this in php by using following code,although there is no direct way to achieve multithreading in php but we can achieve almost same results by following way.
chdir(dirname(__FILE__)); //if you want to run this file as cron job
for ($i = 0; $i < 2; $i += 1){
exec("php test_1.php $i > test.txt &");
//this will execute test_1.php and will leave this process executing in the background and will go
//to next iteration of the loop immediately without waiting the completion of the script in the
//test_1.php , $i is passed as argument .
}
Test_1.php
$conn=mysql_connect($host,$user,$pass);
$db=mysql_select_db($db);
$i = $argv[1]; //this is the argument passed from index.php file
for($j = 0;$j<5000; $j ++)
{
mysql_query("insert into test set
id='$i',
comment='test',
datetime=NOW() ");
}
This will execute test_1.php two times simultaneously and both process will run in the background simultaneously ,so in this way you can achieve multithreading in php.
This guy done really good work Multithreading in php