如何使用 C 在 Linux 上以编程方式终止进程树 [英] How to kill a process tree programmatically on Linux using C

问题描述

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，然后在它没有完成时终止它:

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:

int sysExecTimeout(const char * exePath, int timeoutSec);

在函数中，我使用 fork 和 execl 来生成子进程，当它超时时，我使用 kill(pid, SIGTERM) 和 kill(pid, SIGKILL) 2 秒后，确保孩子死亡:

In the function, I use fork and execl to 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:

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);
    }
}

我使用的是 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 调用只会杀死 /bin/sh 进程并保持 exePath 命令运行，因为它是 /bin/sh 命令的子进程代码>/bin/sh.

I am using Linux, and it seems that when a parent process dies, the child is not killed automatically. So the two kill calls will just kill the /bin/sh process and leave the exePath command running, since it is a child process of /bin/sh.

我正在尝试编写 sysExecTimeout 函数，以便它终止以 pid 为根的整个进程树，其中 pid 是来自pid = fork()

I am trying to write the sysExecTimeout function such that it kills the entire process tree rooted at pid, where pid is the PID from pid = fork()

我需要这个，因为 exePath 命令会产生其他命令，这些命令也会产生其他命令，这些命令可能会卡住并消耗资源.

I need this because the exePath command will spawn other commands, which can also spawn other commands, which could get stuck and consume resources.

我无法控制执行的 exePath 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 do not have control over the exePath binaries/scripts that get executed, so I cannot write my own parent-dies-so-kill-the-children logic in them.

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 tried using kill(0, SIGTERM), which almost did the job, except it also killed my own process :)

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"，这样整个过程树就开始了来自该程序的死亡(假设可以遵循 PID/PPID 链).

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).

我可以在这里使用那个标志:

I could use that flag here:

if(pid == 0) {
    turnOnRecursiveDeathFlag();

    system(exePath);
    //execl("/bin/sh", "sh", "-c", exePath);
    exit(127);
}

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 ps -ef 的 hack，或者修改您正在运行的子进程等.

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.

推荐答案

在子进程中使用 setpgid 来设置它的 GPID 等于它自己的 PID.然后父级可以 kill(-pid,...) 向整个组发出信号.

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.

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);
    }
}

应该可以.

还有一件事，当您生成 shell 时，请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"没问题.

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.

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