The Pool class

(PECL pthreads >= 2.0.0)

Introduction

A Pool is a container for, and controller of, an adjustable number of Workers.

Pooling provides a higher level abstraction of the Worker functionality, including the management of references in the way required by pthreads.

Class synopsis

Pool {
/* Properties */
protected $size ;
protected $class ;
protected $workers ;
protected $work ;
protected $ctor ;
protected $last ;
/* Methods */
public void collect ( Callable $collector )
public Pool __construct ( integer $size , string $class [, array $ctor ] )
public void resize ( integer $size )
public void shutdown ( void )
public integer submit ( Threaded $task )
public integer submitTo ( integer $worker , Threaded $task )
}

Properties

size

maximum number of Workers this Pool can use

class

the class of the Worker

ctor

the arguments for constructor of new Workers

workers

references to Workers

work

references to Threaded objects submitted to the Pool

last

offset in workers of the last Worker used

Table of Contents

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User Contributed Notes 3 notes

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5
olavk
1 year ago
Simple example with Collectable (basically Thread meant for Pool) and Pool

<?php

class job extends Collectable {
  public
$val;

  public function
__construct($val){
   
// init some properties
   
$this->val = $val;
  }
  public function
run(){
   
// do some work
   
$this->val = $this->val . file_get_contents('http://www.example.com/', null, null, 3, 20);
   
$this->setGarbage();
  }
}

// At most 3 threads will work at once
$p = new Pool(3);

$tasks = array(
  new
job('0'),
  new
job('1'),
  new
job('2'),
  new
job('3'),
  new
job('4'),
  new
job('5'),
  new
job('6'),
  new
job('7'),
  new
job('8'),
  new
job('9'),
  new
job('10'),
);
// Add tasks to pool queue
foreach ($tasks as $task) {
 
$p->submit($task);
}

// shutdown will wait for current queue to be completed
$p->shutdown();
// garbage collection check / read results
$p->collect(function($checkingTask){
  echo
$checkingTask->val;
  return
$checkingTask->isGarbage();
});

?>
up
2
meadowsjared at gmail dot com
4 months ago
Please note, when using the collect function, it's important that you extend the pool class so you can keep checking for finished threads until they're all done.

<?php
class TestWork extends Threaded {
    protected
$complete;
   
//$pData is the data sent to your worker thread to do it's job.
   
public function __construct($pData){
       
//transfer all the variables to local variables
       
$this->complete = false;
       
$this->testData = $pData;
    }
   
//This is where all of your work will be done.
   
public function run(){
       
usleep(2000000); //sleep 2 seconds to simulate a large job
       
$this->complete = true;
    }
    public function
isGarbage() {
        return
$this->complete;
    }
}
class
ExamplePool extends Pool
{
    public
$data = array();
    public function
process()
    {
       
// Run this loop as long as we have
        // jobs in the pool
       
while (count($this->work)) {
           
$this->collect(function (TestWork $task) {
               
// If a task was marked as done
                // collect its results
               
if ($task->isGarbage()) {
                   
$tmpObj = new stdclass();
                   
$tmpObj->complete = $task->complete;
                   
//this is how you get your completed data back out [accessed by $pool->process()]
                   
$this->data[] = $tmpObj;
                }
                return
$task->isGarbage();
            });
        }
       
// All jobs are done
        // we can shutdown the pool
       
$this->shutdown();
        return
$this->data;
    }
}
$pool = new ExamplePool(3);
$testData = 'asdf';
for(
$i=0;$i<5;$i++) {
   
$pool->submit(new TestWork($testData));
}
$retArr = $pool->process(); //get all of the results
echo '<pre>';
print_r($retArr); //return the array of results (and maybe errors)
echo '</pre>';
?>
up
-4
fajan
2 years ago
Example class to demonstrate usage of Pool/Worker mechanism, also to show a few tricks & hints ;)
<?php
class Config extends Threaded{    // shared global object
   
protected $val=0, $val2=0;
    protected function
inc(){++$this->val;}    // protected synchronizes by-object
   
public function inc2(){++$this->val2;}    // no synchronization
}
class
WorkerClass extends Worker{
    protected static
$worker_id_next = -1;
    protected
$worker_id;
    protected
$config;
    public function
__construct($config){
       
$this->worker_id = ++static::$worker_id_next;    // static members are not avalable in thread but are in 'main thread'
       
$this->config = $config;
    }
    public function
run(){
        global
$config;
       
$config = $this->config;    // NOTE: setting by reference WON'T work
       
global $worker_id;
       
$worker_id = $this->worker_id;
        echo
"working context {$worker_id} is created!\n";
       
//$this->say_config();    // globally synchronized function.
   
}
    protected function
say_config(){    // 'protected' is synchronized by-object so WON'T work between multiple instances
       
global $config;        // you can use the shared $config object as synchronization source.
       
$config->synchronized(function() use (&$config){    // NOTE: you can use Closures here, but if you attach a Closure to a Threaded object it will be destroyed as can't be serialized
           
var_dump($config);
        });
    }
}
class
Task extends Stackable{    // Stackable still exists, it's just somehow dissappeared from docs (probably by mistake). See older version's docs for more details.
   
protected $set;
    public function
__construct($set){
       
$this->set = $set;
    }
    public function
run(){
        global
$worker_id;
        echo
"task is running in {$worker_id}!\n";
       
usleep(mt_rand(1,100)*100);
       
$config = $this->getConfig();
       
$val = $config->arr->shift();
       
$config->arr[] = $this->set;
        for (
$i = 0 ; $i < 1000; ++$i){
           
$config->inc();
           
$config->inc2();
        }
    }
    public function
getConfig(){
        global
$config;    // WorkerClass set this on thread's scope, can be reused by Tasks for additional asynch data source. (ie: connection pool or taskqueue to demultiplexer)
       
return $config;
    }
}

$config = new Config;
$config->arr = new \Threaded();
$config->arr->merge(array(1,2,3,4,5,6));
class
PoolClass extends Pool{
    public function
worker_list(){
        if (
$this->workers !== null)
            return
array_keys($this->workers);
        return
null;
    }
}
$pool = new PoolClass(3, 'WorkerClass', [$config] );
$pool->worker_list();
//$pool->submitTo(0,new Task(-10));    // submitTo DOES NOT try to create worker

$spammed_id = -1;
for (
$i = 1; $i <= 100; ++$i){    // add some jobs
   
if ($spammed_id == -1 && ($x = $pool->worker_list())!= null && @$x[2]){
       
$spammed_id = $x[2];
        echo
"spamming worker {$spammed_id} with lots of tasks from now on\n";
    }
    if (
$spammed_id != -1 && ($i % 5) == 0)    // every 5th job is routed to one worker, so it has 20% of the total jobs (with 3 workers it should do ~33%, not it has (33+20)%, so only delegate to worker if you plan to do balancing as well... )
       
$pool->submitTo($spammed_id,new Task(10*$i));   
    else
       
$pool->submit(new Task(10*$i));
}
$pool->shutdown();
var_dump($config); // "val" is exactly 100000, "val2" is probably a bit less
// also: if you disable the spammer, you'll that the order of the "arr" is random.
?>
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