PHP multi-threading implementation example

php multi-threading For many friends who have just come into contact with php, they don’t understand what it means and what it is used for. So today we will explain to you the implementation case of php multi-threading!

Suppose we are running the file a.php now. But in the program, I request the WEB server to run another b.php

Then the two files will be executed at the same time.

(PS: After a link request is sent, the WEB server will execute it, regardless of whether the client has exited)

Sometimes, what we want to run is not another file, but What should I do with part of the code in this file?

In fact, it uses parameters to control which program a.php runs.

Let’s look at an example:

//a.php

PHP代码:--------------------------------------------------------------------------------
<?php
    function runThread()
    {
        $fp = fsockopen(&#39;localhost&#39;, 80, $errno, $errmsg);
        
        fputs($fp, "GET /a.php?act=b\r\n\r\n");        //这里的第二个参数是HTTP协议中规定的请求头
                                //不明白的请看RFC中的定义
        
        fclose($fp);
    }
    function a()
    {
        $fp = fopen(&#39;result_a.log&#39;, &#39;w&#39;);
        fputs($fp, &#39;Set in &#39; . Date(&#39;h:i:s&#39;, time()) . (double)microtime() . "\r\n");
        
        fclose($fp);        
    }
    function b()
    {
        $fp = fopen(&#39;result_b.log&#39;, &#39;w&#39;);
        fputs($fp, &#39;Set in &#39; . Date(&#39;h:i:s&#39;, time()) . (double)microtime() . "\r\n");
        
        fclose($fp);        
    }
    if(!isset($_GET[&#39;act&#39;])) $_GET[&#39;act&#39;] = &#39;a&#39;;
    
    if($_GET[&#39;act&#39;] == &#39;a&#39;)
    {
        runThread();
        a();
    }
    else if($_GET[&#39;act&#39;] == &#39;b&#39;) b();
?>
--------------------------------------------------------------------------------

Open result_a.log and result_b.log and compare the access times of the two files. You will find that these two are indeed running in different threads.
Some times are exactly the same.

The above is just a simple example, you can improve it into other forms.

Now that PHP can also have multi-threading, the problem also arises, that is, the problem of synchronization. We know that PHP It does not support multi-threading. So there is nothing like the synchronize method in

java. So what should we do?

1. Try not to access the same resource. To avoid conflicts. But you can perform database operations at the same time. Because the database supports concurrent operations, so in multi-threaded PHP

do not write data to the same file. If necessary If you want to write, use other methods for synchronization. For example, call Beijing Tianan Gynecological Hospital flock to lock the file, etc. Or create a temporary file

and wait for the disappearance of this file in another thread while(file_exits ('xxx')); This means that when this temporary file exists, it means that the thread is actually operating.

If there is no such file, it means that other threads have released it.

2. Try your best Do not read data from the socket that runThread takes after executing fputs. Because to achieve multi-threading, it is necessary to use non-blocking mode. That is, return immediately when a function like fgets

is executed. So read and write There will be problems with the data. If blocking mode is used, the program is not multi-threaded. It has to wait for the return of the above before executing the

following program. So if you need to exchange data, finally use external files or data Completed. If you really want it, use socket_set_nonblock($fp) to achieve it.

Summary:

Having said so much, here’s the bottom line Is there any practical significance? When is it necessary to use this method?

The answer is yes. As we all know, in an application that continuously reads network resources, the speed of the network is the bottleneck. If you adopt this form, you can read

different pages with multiple threads at the same time.

Related recommendations:

An implementation method of PHP multi-threading—shell

PHP multi-threading small case

About PHP multi-threading issues

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