PHP asynchronous data execution method

This article mainly introduces the method of PHP asynchronous data execution. Interested friends can refer to it. I hope it will be helpful to everyone.

The code is as follows:

<?php
$count = count($emailarr);
for($i =0; $i < $count; $i++)
{
　　sendmail();//发送邮件
}
?>

This code has a very poor user experience and cannot be used in practice. First, sending so many emails will cause the server to run timeout. In fact, the long user waiting time will make the user System product doubts and loss of confidence. However, the user does not need to wait until all 1,000 emails have been sent before submitting the message successfully. We can directly prompt the user to send the message successfully after submitting it to the background, and then let the background program silently send it one by one.
At this time we need "asynchronous execution" technology to execute the code. The characteristic of asynchronous execution is silent execution in the background. The user does not need to wait for the execution result of the code. The benefits of using asynchronous execution:

• Get rid of the application's dependence on a single task

• Improve the execution efficiency of the program

• Improves the scalability of the program

• Improved user experience in certain scenarios

• Because PHP does not support multi-threading, use asynchronous calling to request multiple HTTPs The parallel execution effect of the program is achieved, but please note that if there are too many HTTP requests, the system overhead will be greatly increased

Common ways of asynchronous execution of PHP1. The client page uses AJAX technology to request the serverThe simplest way is to embed an AJAX call in the HTML code returned to the client, or embed a img tag, src points to the time-consuming script to be executed. This method is the simplest and fastest. The server does not need to make any calls.
But the disadvantage is that generally speaking, Ajax should be triggered after onLoad. That is to say, if the user clicks on the page and then closes it, our background script will not be triggered.
If you use the img tag, this method cannot be called asynchronous execution in the strict sense. The user's browser will wait for a long time for the execution of the php script to be completed, that is, the status bar of the user's browser always shows that it is still loading. Of course, other methods with similar principles can also be used, such as script tags and so on.
2. popen() functionresource popen (string command, string mode);
Open a pipe pointing to the process that is generated by the execution of the given command command. Opens a pipe to the process spawned by execution of the command that spawned the given command. So you can pass it by calling it, but ignore its output.
pclose(popen("/home/xinchen/backend.php &", 'r'));
This method avoids the shortcomings of the first method and is also fast. But the problem is that this method cannot request another WebService through the HTTP protocol and can only execute local script files. And it can only be opened in one direction, and cannot pass a large number of parameters to the called script. And if the number of visits is high, a large number of processes will be generated. If you use external resources, you have to consider the competition yourself.
3. CURL extension CURL is a powerful HTTP command line tool that can simulate HTTP requests such as POST/GET, and then obtain and extract data and display it on "standard output" (stdout).

$ch = curl_init();
$curl_opt = array(CURLOPT_URL, 'http://www.example.com/backend.php',
       CURLOPT_RETURNTRANSFER, 1,
       CURLOPT_TIMEOUT, 1,);

curl_setopt_array($ch, $curl_opt);
curl_exec($ch);
curl_close($ch);

Using CURL requires setting CUROPT_TIMEOUT to 1 (the minimum is 1, depressed). That is, the client must wait at least 1 second.
4. fscokopen() function fsockopen is a very powerful function that supports socket programming. You can use fsockopen to implement socket programs such as email sending, etc. To use fcockopen, you need to manually splice out the header part.

$fp = fsockopen(www.jb51.net, 80, $errno, $errstr, 30);
if (!$fp) {
 echo "$errstr ($errno)<br />\n";
} else {
 $out = "GET /backend.php / HTTP/1.1\r\n";
 $out .= "Host: www.jb51.net\r\n";
 $out .= "Connection: Close\r\n\r\n";

 fwrite($fp, $out);
 /*忽略执行结果
 while (!feof($fp)) {
  echo fgets($fp, 128);
 }*/
 fclose($fp);
}

Summary: The above is the entire content of this article, I hope it will be helpful to everyone's study.

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