僵尸进程无法通过waitpid调用进行清理

问题描述

我正在观察使用htop的进程，即使我使用waitpid调用进行清理，我仍然看到子进程保持僵尸状态。知道为什么会发生这种情况吗？

非常感谢您！

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#include <errno.h>
#include <unistd.h>
#include <sys/types.h>
#include <signal.h>

void child_signal_handler(int signal) {
  printf("Someone is stabbed me with signal %d\n",signal);
}

int main(int argc,char** argv)
{
  const pid_t child = fork();

  if (child == 0) {
    struct sigaction sa;
    memset(&sa,sizeof(sa));
    sa.sa_handler = &child_signal_handler;
    sigaction(SIGTERM,&sa,NULL);
    printf("Child is started in busy loop\n");
    while (true)
      ;
  } else {
    const int mercy_period = 3;
    printf("Parent is angry and gonna kill his child in %d sec\n",mercy_period);
    sleep(mercy_period);
    kill(child,SIGTERM);
    // clean-up zombie child process as it is terminated before we can wait on
    // it
    int status = 0;
    while(waitpid(-1,&status,WNOHANG) > 0);
  }

  return EXIT_SUCCESS;
}

解决方法

waitpid glibc实施注释

如果PID为（pid_t）-1，则匹配任何进程。如果在选项中将WNOHANG位置1，则该孩子 还没死，返回（pid_t）0。

由于_amazonses Pe82YD6rnCI0AXMHIZv8v0h/thYRZk97YCuQUA= 为假，因此while循环显然会立即退出。

将0 > 0和信号更改为else

SIGKILL

几次尝试后，} else { const int mercy_period = 3; printf("Parent is angry and gonna kill his child in %d sec\n",mercy_period); sleep(mercy_period); kill(child,SIGKILL); int status = 0; pid_t pid = waitpid(-1,&status,WNOHANG); while(!pid) { pid = waitpid(-1,WNOHANG); printf("%d\n",pid); } } 将返回子进程的pid。成功。