Detailed explanation of PHP multi-threading implementation methods and usage examples

Now let’s introduce the specific PHP multi-threading implementation program code. Students who need to know more can refer to it.
When someone wants to implement concurrency functions, they usually think of using fork or spawn threads, but when they find that PHP does not support multi-threading, they may change their minds and use some not good enough languages, such as perl.
In fact, in most cases, you don't need to use fork or thread, and you will get better performance than using fork or thread.
Suppose you want to build a service to check n running servers to make sure they are still functioning normally. You might write code like the following:
The code is as follows

<?php
$hosts = array("host1.sample.com", "host2.sample.com", "host3.sample.com");
$timeout = 15;
$status = array();
foreach ($hosts as $host) {
 $errno = 0;
 $errstr = "";
 $s = fsockopen($host, 80, $errno, $errstr, $timeout);
 if ($s) {
 $status[$host] = "Connectedn";
 fwrite($s, "HEAD / HTTP/1.0rnHost: $hostrnrn");
 do {
  $data = fread($s, 8192);
  if (strlen($data) == 0) {
  break;
  }
  $status[$host] .= $data;
 } while (true);
 fclose($s);
 } else {
 $status[$host] = "Connection failed: $errno $errstrn";
 }
}
print_r($status);
?>

It runs well, but before fsockopen() analyzes the hostname and establishes a successful connection (or delays $timeout seconds), expand this code to Managing a large number of servers will take a long time.
So we have to abandon this code; we can establish an asynchronous connection - no need to wait for fsockopen to return connection status. PHP still needs to resolve the hostname (so it's more sensible to use the ip directly), but it will return immediately after opening a connection, and then we can connect to the next server.
There are two ways to achieve this: In PHP5, you can use the new stream_socket_client() function to directly replace fsocketopen(). For versions before PHP5, you need to do it yourself and use sockets extension to solve the problem.
The following is the solution in PHP5:
The code is as follows

<?php
$hosts = array("host1.sample.com", "host2.sample.com", "host3.sample.com");
$timeout = 15;
$status = array();
$sockets = array();
/* Initiate connections to all the hosts simultaneously */
foreach ($hosts as $id => $host) {
 $s = stream_socket_client("
$
$host:80", $errno, $errstr, $timeout,
 STREAM_CLIENT_ASYNC_CONNECT|STREAM_CLIENT_CONNECT);
 if ($s) {
 $sockets[$id] = $s;
 $status[$id] = "in progress";
 } else {
 $status[$id] = "failed, $errno $errstr";
 }
}
/* Now, wait for the results to come back in */
while (count($sockets)) {
 $read = $write = $sockets;
 /* This is the magic function - explained below */
 $n = stream_select($read, $write, $e = null, $timeout);
 if ($n > 0) {
 /* readable sockets either have data for us, or are failed
  * connection attempts */
 foreach ($read as $r) {
   $id = array_search($r, $sockets);
   $data = fread($r, 8192);
   if (strlen($data) == 0) {
  if ($status[$id] == "in progress") {
  $status[$id] = "failed to connect";
  }
  fclose($r);
  unset($sockets[$id]);
   } else {
  $status[$id] .= $data;
   }
 }
 /* writeable sockets can accept an HTTP request */
 foreach ($write as $w) {
  $id = array_search($w, $sockets);
  fwrite($w, "HEAD / HTTP/1.0rnHost: "
  . $hosts[$id] . "rnrn");
  $status[$id] = "waiting for response";
 }
 } else {
 /* timed out waiting; assume that all hosts associated
  * with $sockets are faulty */
 foreach ($sockets as $id => $s) {
  $status[$id] = "timed out " . $status[$id];
 }
 break;
 }
}
foreach ($hosts as $id => $host) {
 echo "Host: $hostn";
 echo "Status: " . $status[$id] . "nn";
} 
?>

We use stream_select() to wait for the connection event of sockets opening. stream_select() calls the system's select(2) function to work: the first three parameters are the arrays of streams you want to use; you can read, write and get exceptions from them (for the three parameters respectively). stream_select() can wait for an event to occur by setting the $timeout (seconds) parameter - when the event occurs, the corresponding socket data will be written to the parameters you passed in.
The following is the implementation of PHP 4.1.0 and later. If you have included sockets (ext/sockets) support when compiling PHP, you can use similar code above, but you need to use ext for the functions of the streams/filesystem function above. /sockets function implementation. The main difference is that we use the following function instead of stream_socket_client() to establish the connection:
The code is as follows

<?php
// This value is correct for Linux, other systems have other values
define(&#39;EINPROGRESS&#39;, 115);
function non_blocking_connect($host, $port, &$errno, &$errstr, $timeout) {
 $ip = gethostbyname($host);
 $s = socket_create(AF_INET, SOCK_STREAM, 0);
 if (socket_set_nonblock($s)) {
 $r = @socket_connect($s, $ip, $port);
 if ($r || socket_last_error() == EINPROGRESS) {
  $errno = EINPROGRESS;
  return $s;
 }
 }
 $errno = socket_last_error($s);
 $errstr = socket_strerror($errno);
 socket_close($s);
 return false;
}
?>

Now replace stream_select() with socket_select(), fread() with socket_read(), and socket_write() fwrite(), replace fclose() with socket_close() and you can execute the script!
The advancement of PHP5 is that you can use stream_select() to process almost any stream - for example, you can use it to receive keyboard input through include STDIN and save it into an array, and you can also receive data from a pipe opened through proc_open() .
Let’s share a PHP multi-threaded class
The code is as follows

* @title:   PHP多线程类(Thread)
 * @version:  1.0
 * 
 * PHP多线程应用示例：
 * require_once 'thread.class.php';
 * $thread = new thread();
 * $thread->addthread('action_log','a');
 * $thread->addthread('action_log','b');
 * $thread->addthread('action_log','c');
 * $thread->runthread();
 * 
 * function action_log($info) {
 *   $log = 'log/' . microtime() . '.log';
 *   $txt = $info . "rnrn" . 'Set in ' . Date('h:i:s', time()) . (double)microtime() . "rn";
 *   $fp = fopen($log, 'w');
 *   fwrite($fp, $txt);
 *   fclose($fp);
 * }
 */
class thread {
  
  var $hooks = array();
  var $args = array();
  
  function thread() {
  }
  
  function addthread($func)
  {
    $args = array_slice(func_get_args(), 1);
    $this->hooks[] = $func;
    $this->args[] = $args;
    return true;
  }
  
  function runthread()
  {
    if(isset($_GET['flag']))
    {
      $flag = intval($_GET['flag']);
    }
    if($flag || $flag === 0)
    {
      call_user_func_array($this->hooks[$flag], $this->args[$flag]);
    }
    else
    {
      for($i = 0, $size = count($this->hooks); $i < $size; $i++)
      {
        $fp=fsockopen($_SERVER[&#39;HTTP_HOST&#39;],$_SERVER[&#39;SERVER_PORT&#39;]);
        if($fp)
        {
          $out = "GET {$_SERVER[&#39;PHP_SELF&#39;]}?flag=$i HTTP/1.1rn";
          $out .= "Host: {$_SERVER[&#39;HTTP_HOST&#39;]}rn";
          $out .= "Connection: Closernrn";
          fputs($fp,$out);
          fclose($fp);
        }
      }
    }
  }
}

I hope this article will be helpful to everyone’s PHP programming design.

For more detailed explanations of PHP multi-threading implementation methods and usage examples, please pay attention to the PHP Chinese website!