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This article mainly introduces the instructions on PHP multi-process execution tasks. It has a certain reference value. Now I share it with you. Friends in need can refer to it.
Yes A specified number of multiple tasks are executed concurrently, and the number of processes is controlled.
The processes are independent of each other and do not affect each other.
Code example:
<?php
$task = 0; //任务id
$taskNum = 10; //任务总数
$processNumLimit = 2; //子进程总量限制
while(true){
//产生分支
$processid = pcntl_fork();
//创建子进程失败
if( $processid == -1 ){
echo "create process error！\n";
exit(1);
}
//主进程，获得子进程pid
elseif($processid){
$task++; //下一个任务
$currentProcessid = posix_getpid(); //当前进程的Id
$parentProcessid = posix_getppid(); // 父级进程的ID
$phpProcessid = getmypid(); //当前php进程的id
echo "task:",$task,"\tprocessid:",$processid,"\tcurrentProcessid:",$currentProcessid,"\tparentProcessid:",$parentProcessid,"\tphpProcessid:",$phpProcessid,"\n";
//控制进程数
if($task >= $processNumLimit) {
echo "wait chl start！\n";
$exitid = pcntl_wait($status); //等待退出
echo "wait chl end！extid:",$exitid,"\tstatus:",$status,"\n";
}
//任务总量控制
if($task >= $taskNum) {
echo "taskNum enough！\n";
break;
}
}
//processid=0为新创建的进程
else{
//模拟不同任务的不同执行时长
$sleep = rand(1, 5);
$currentProcessid = posix_getpid(); //当前进程的Id
$parentProcessid = posix_getppid(); // 父级进程的ID
$phpProcessid = getmypid(); //当前php进程的id
echo "task:",$task,"\tprocessid:",$processid,"\tcurrentProcessid:",$currentProcessid,"\tparentProcessid:",$parentProcessid,"\tphpProcessid:",$phpProcessid,"\tsleep:",$sleep,"\tbegin!\n";
sleep($sleep);
echo "task:",$task,"\tprocessid:",$processid,"\tcurrentProcessid:",$currentProcessid,"\tparentProcessid:",$parentProcessid,"\tphpProcessid:",$phpProcessid,"\tsleep:",$sleep,"\tend!\n";
exit(0); //子进程执行完后退出，防止进入循环创建子进程
}
}Result of execution:
task:1 processid:32225 currentProcessid:32224 parentProcessid:15053 phpProcessid:32224 task:0 processid:0 currentProcessid:32225 parentProcessid:32224 phpProcessid:32225 sleep:5 begin! task:2 processid:32226 currentProcessid:32224 parentProcessid:15053 phpProcessid:32224 wait chl start！ task:1 processid:0 currentProcessid:32226 parentProcessid:32224 phpProcessid:32226 sleep:2 begin! task:1 processid:0 currentProcessid:32226 parentProcessid:32224 phpProcessid:32226 sleep:2 end! wait chl end！extid:32226 status:0 task:3 processid:32228 currentProcessid:32224 parentProcessid:15053 phpProcessid:32224 wait chl start！ task:2 processid:0 currentProcessid:32228 parentProcessid:32224 phpProcessid:32228 sleep:1 begin! task:2 processid:0 currentProcessid:32228 parentProcessid:32224 phpProcessid:32228 sleep:1 end! wait chl end！extid:32228 status:0 task:4 processid:32229 currentProcessid:32224 parentProcessid:15053 phpProcessid:32224 wait chl start！ task:3 processid:0 currentProcessid:32229 parentProcessid:32224 phpProcessid:32229 sleep:2 begin! task:0 processid:0 currentProcessid:32225 parentProcessid:32224 phpProcessid:32225 sleep:5 end! wait chl end！extid:32225 status:0 task:5 processid:32270 currentProcessid:32224 parentProcessid:15053 phpProcessid:32224 wait chl start！ task:4 processid:0 currentProcessid:32270 parentProcessid:32224 phpProcessid:32270 sleep:1 begin! task:3 processid:0 currentProcessid:32229 parentProcessid:32224 phpProcessid:32229 sleep:2 end! wait chl end！extid:32229 status:0 task:6 processid:32271 currentProcessid:32224 parentProcessid:15053 phpProcessid:32224 wait chl start！ task:5 processid:0 currentProcessid:32271 parentProcessid:32224 phpProcessid:32271 sleep:4 begin! task:4 processid:0 currentProcessid:32270 parentProcessid:32224 phpProcessid:32270 sleep:1 end! wait chl end！extid:32270 status:0 task:7 processid:32273 currentProcessid:32224 parentProcessid:15053 phpProcessid:32224 wait chl start！ task:6 processid:0 currentProcessid:32273 parentProcessid:32224 phpProcessid:32273 sleep:1 begin! task:6 processid:0 currentProcessid:32273 parentProcessid:32224 phpProcessid:32273 sleep:1 end! wait chl end！extid:32273 status:0 task:8 processid:32274 currentProcessid:32224 parentProcessid:15053 phpProcessid:32224 wait chl start！ task:7 processid:0 currentProcessid:32274 parentProcessid:32224 phpProcessid:32274 sleep:2 begin! task:5 processid:0 currentProcessid:32271 parentProcessid:32224 phpProcessid:32271 sleep:4 end! task:7 processid:0 currentProcessid:32274 parentProcessid:32224 phpProcessid:32274 sleep:2 end! wait chl end！extid:32274 status:0 task:9 processid:32277 currentProcessid:32224 parentProcessid:15053 phpProcessid:32224 wait chl start！ wait chl end！extid:32271 status:0 task:8 processid:0 currentProcessid:32277 parentProcessid:32224 phpProcessid:32277 sleep:2 begin! task:10 processid:32278 currentProcessid:32224 parentProcessid:15053 phpProcessid:32224 wait chl start！ task:9 processid:0 currentProcessid:32278 parentProcessid:32224 phpProcessid:32278 sleep:2 begin! task:8 processid:0 currentProcessid:32277 parentProcessid:32224 phpProcessid:32277 sleep:2 end! task:9 processid:0 currentProcessid:32278 parentProcessid:32224 phpProcessid:32278 sleep:2 end! wait chl end！extid:32277 status:0 taskNum enough
After pcntl_fork creates a child process, The child process executes the function code, and the parent process continues to increment the task id and create the next task process;
Wait through pcntl_wait for a child process to finish executing and exit, then create a new process to achieve the total number of processes Control;
After the main process completes creation, exit the loop through break. There may be child processes continuing to execute at this time.
Generate a branch (child process) at the current position of the current process. On success, the PID of the generated child process is returned in the parent process execution thread, and 0 is returned in the child process execution thread. On failure, -1 is returned in the parent process context, the child process is not created, and a PHP error is raised.
Wait or return the child process status of fork. The wait function scrapes the execution of the current process until a child process exits or receives a signal that requires interrupting the current process or calling a signal handling function. If a child process has exited when this function is called (commonly known as a zombie process), this function returns immediately. All system resources used by the child process will be released.
1. Problems with zombie processes and orphan processes
Some zombie processes obtain status and release resources by pcntl_wait, and processes that have not been taken over become Orphan process. The orphan process is adopted by the init process to complete wait's status acquisition and resource release.
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