What is the php multi-process function?

When running scripts on the server, some time-consuming tasks cannot be avoided, and the use of multiple processes is essential. After PHP5.5, PHP began to add multi-process elements to meet development needs.

Recommended courses:PHP Tutorial.

php multi-process is generally used to execute php scripts in the php_cli command line to implement expansions that need to be enabled for multiple processes: pcntl, posix (pcntl is the abbreviation of process control process management) . Multi-process programming of PHP is not supported in the Windows environment. This article is mainly developed and tested in the Linux environment.

pcntl_fork — Generates a branch (child process) at the current position of the current process.
Basic example of a fork sub-process:

$pid = pcntl_fork(); //父进程和子进程都会执行下面代码 if ($pid == -1) { //错误处理：创建子进程失败时返回-1. die('could not fork'); } else if ($pid) { //父进程会得到子进程号，所以这里是父进程执行的逻辑 pcntl_wait($status); //等待子进程中断，防止子进程成为僵尸进程。 } else { //子进程得到的$pid为0, 所以这里是子进程执行的逻辑。 }

If a task is broken down into multiple processes for execution, the overall time-consuming will be reduced.
For example, there is a relatively large data file to be processed. This file consists of many lines. If a single process executes the tasks to be processed, it will take a long time if the volume is large. At this time, multiple processes can be considered.

Let’s look at an interview question. There is an int array with 10 million elements that needs to be summed. It is divided equally into 4 processes for processing. Each process processes a part, and then the results are counted. The code is as follows

      
In the appeal answer, the array is divided into 4 sub-arrays and processed by 4 sub-processes respectively. However, there is no way to add the calculated results because the processes complete the tasks independently and there is no way to share the same process. A (memory) variable, message queue will be introduced below to solve the problem of process communication
      

      
      
The above is the detailed content of What is the php multi-process function?. For more information, please follow other related articles on the PHP Chinese website!