我希望有人可以阐明如何让父进程等待所有子进程完成,然后再继续分叉。我有我想运行的清理代码,但子进程需要在这发生之前返回。
for (int id=0; id<n; id++) {
if (fork()==0) {
// Child
exit(0);
} else {
// Parent
...
}
...
}
我希望有人可以阐明如何让父进程等待所有子进程完成,然后再继续分叉。我有我想运行的清理代码,但子进程需要在这发生之前返回。
for (int id=0; id<n; id++) {
if (fork()==0) {
// Child
exit(0);
} else {
// Parent
...
}
...
}
pid_t child_pid, wpid;
int status = 0;
//Father code (before child processes start)
for (int id=0; id<n; id++) {
if ((child_pid = fork()) == 0) {
//child code
exit(0);
}
}
while ((wpid = wait(&status)) > 0); // this way, the father waits for all the child processes
//Father code (After all child processes end)
wait
等待子进程终止,并返回该子进程的pid
. 出错时(例如,当没有子进程时),-1
返回。所以,基本上,代码一直在等待子进程完成,直到出现wait
ing 错误,然后你就知道它们都完成了。
Use waitpid() like this:
pid_t childPid; // the child process that the execution will soon run inside of.
childPid = fork();
if(childPid == 0) // fork succeeded
{
// Do something
exit(0);
}
else if(childPid < 0) // fork failed
{
// log the error
}
else // Main (parent) process after fork succeeds
{
int returnStatus;
waitpid(childPid, &returnStatus, 0); // Parent process waits here for child to terminate.
if (returnStatus == 0) // Verify child process terminated without error.
{
printf("The child process terminated normally.");
}
if (returnStatus == 1)
{
printf("The child process terminated with an error!.");
}
}
只需使用:
while(wait(NULL) > 0);
这可确保您等待所有子进程,并且只有当所有子进程都返回时,您才转到下一条指令。