如何使用 C 在 Linux 上以编程方式终止进程树
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How to kill a process tree programmatically on Linux using C
提问by Alin Tomescu
I am trying to write a function that spawns a child process, lets it run for a certain amount of time and then kills it if it hasn't finished:
我正在尝试编写一个生成子进程的函数，让它运行一段时间，然后在它尚未完成时将其杀死：
int sysExecTimeout(const char * exePath, int timeoutSec);
In the function, I use forkand execlto spawn the child, and, when it times out, I use kill(pid, SIGTERM)and kill(pid, SIGKILL)after 2 seconds, to ensure the child dies:
在函数中，我使用forkandexecl来生成孩子，当它超时时，我使用kill(pid, SIGTERM)and kill(pid, SIGKILL)2 秒后，以确保孩子死亡：
pid_t pid = fork();
if(pid == 0) {
execl("/bin/sh", "sh", "-c", exePath);
exit(127);
} else if(pid != -1) {
// timeout code
if(timeout) {
kill(pid, SIGTERM);
sleep(2);
kill(pid, SIGKILL);
}
}
I am using Linux, and it seems that when a parent process dies, the child is not killed automatically. So the two killcalls will just kill the /bin/shprocess and leave the exePathcommand running, since it is a child process of /bin/sh.
我正在使用 Linux，似乎当父进程死亡时，子进程不会自动终止。所以这两个kill调用只会终止/bin/sh进程并保持exePath命令运行，因为它是/bin/sh.
I am trying to write the sysExecTimeoutfunction such that it kills the entire process tree rooted at pid, where pidis the PID from pid = fork()
我正在尝试编写sysExecTimeout函数，以便它杀死以 为根的整个进程树pid，pidPID 来自何处pid = fork()
I need this because the exePathcommand will spawn other commands, which can also spawn other commands, which could get stuck and consume resources.
我需要这个，因为该exePath命令会产生其他命令，这些命令也可能产生其他命令，这些命令可能会卡住并消耗资源。
I do not have control over the exePathbinaries/scripts that get executed, so I cannot write my own parent-dies-so-kill-the-children logic in them.
我无法控制exePath执行的二进制文件/脚本，因此我无法在其中编写自己的 parent-dies-so-kill-the-children 逻辑。
I tried using kill(0, SIGTERM), which almost did the job, except it also killed my own process :)
我尝试使用kill(0, SIGTERM)，它几乎完成了工作，除了它也杀死了我自己的进程:)
I am wondering if there is a flag I can turn on programatically in C that says "hey man, when I die, take all my children and kill them, and repeat recursively for their children" such that the entire process tree started from that program dies (assuming the PID/PPID chain can be followed).
我想知道是否有一个标志可以在 C 中以编程方式打开，上面写着“嘿，伙计，当我死时，带走我所有的孩子并杀死他们，并为他们的孩子递归重复”，这样整个流程树就从该程序开始模具（假设可以遵循 PID/PPID 链）。
I could use that flag here:
我可以在这里使用那个标志：
if(pid == 0) {
turnOnRecursiveDeathFlag();
system(exePath);
//execl("/bin/sh", "sh", "-c", exePath);
exit(127);
}
Is there a way to do that? I've been searching for a while, but all I can find are hacks using ps -ef, or modifying the children processes that you are running etc.
有没有办法做到这一点？我已经搜索了一段时间，但我能找到的只是使用 hackps -ef或修改您正在运行的子进程等。
采纳答案by DoxyLover
Use setpgid in the child to set its GPID equal to its own PID. The parent then can kill(-pid,...) to signal the entire group.
在子进程中使用 setpgid 将其 GPID 设置为等于其自己的 PID。然后父级可以 kill(-pid,...) 向整个组发出信号。
pid_t pid = fork();
if(pid == 0) {
setpgid(0, 0);
execl("/bin/sh", "sh", "-c", exePath);
exit(127);
} else if(pid == -1) {
// timeout code
if(timeout) {
kill(-pid, SIGTERM);
sleep(2);
kill(-pid, SIGKILL);
}
}
That should do it.
那应该这样做。
One more thing, when you spawn a shell, make sure it doesn't enable job control. Otherwise, it will create its own process groups. Your "/bin/sh -c" is fine.
还有一件事，当你生成一个 shell 时，确保它没有启用作业控制。否则，它将创建自己的进程组。你的“/bin/sh -c”很好。
