How to implement multi-threading in PHP-PHP Tutorial-php.cn

Multi-threading is a very good thing in Java. Many friends say that PHP multi-threading cannot be used in PHP. In fact, that is a wrong statement. This article introduces two implementation methods of multi-threading in PHP. If you are interested Students can take a look.

Does PHP itself support multi-threading, but we can use other methods to achieve multi-threading, such as shell services, such as web servers. In this article, we will talk about how to implement these two methods. Friends in need can come and refer to it.

Multi-threading is a very good thing in Java. Many friends say that PHP multi-threading cannot be used in PHP. In fact, that is a wrong statement. The PHP multi-threading implementation method is related to the fsockopen function. Below we will introduce the specific 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 something that is not good enough. Language, 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);
?>

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it This works fine, but scaling this code to manage a large number of servers would take a long time until fsockopen() has parsed the hostname and established a successful connection (or delayed $timeout seconds).

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:

It runs very well, but after fsockopen() parses the hostname and creates one successfully Scaling this code to manage a large number of servers would take a long time before connecting (or delaying $timeout seconds).

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";
} 
?>

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We use stream_select() to wait for the connection opened by sockets event. 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 PHP4.1.0 and later versions. If you have included sockets (ext/sockets) support when compiling PHP, you can use similar code as above, just need to change the above The functions of streams/filesystem functions are implemented using ext/sockets functions. 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;
}
?>

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Now use socket_select() to replace stream_select(), use socket_read() to replace fread(), use socket_write() to replace fwrite(), use socket_close() to replace fclose() and you can execute Scripted!

The advanced thing about 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 it through proc_open () data in the opened pipe.

Let’s share a PHP multi-threaded class

The code is as follows:

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[&#39;flag&#39;]))
  {
   $flag = intval($_GET[&#39;flag&#39;]);
  }
  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);
    }
   }
  }
 }
}

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