k8s pause 容器


在kubernetes的v1.0.0中,pause的实现非常简单:

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func main() {
	c := make(chan os.Signal, 1)
	signal.Notify(c, os.Interrupt, os.Kill, syscall.SIGTERM)

	// Block until a signal is received.
	<-c
}

其中: os.Interrupt, os.Kill分别是syscall.SIGINT, syscall.SIGKILL

在之后的版本中,该用c实现。

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#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>

static void sigdown(int signo) {
  psignal(signo, "Shutting down, got signal");
  exit(0);
}

static void sigreap(int signo) {
  while (waitpid(-1, NULL, WNOHANG) > 0);
}

int main() {
  if (getpid() != 1)
    /* Not an error because pause sees use outside of infra containers. */
    fprintf(stderr, "Warning: pause should be the first process\n");

  if (sigaction(SIGINT, &(struct sigaction){.sa_handler = sigdown}, NULL) < 0)
    return 1;
  if (sigaction(SIGTERM, &(struct sigaction){.sa_handler = sigdown}, NULL) < 0)
    return 2;
  if (sigaction(SIGCHLD, &(struct sigaction){.sa_handler = sigreap,
                                             .sa_flags = SA_NOCLDSTOP},
                NULL) < 0)
    return 3;

  for (;;)
    pause();
  fprintf(stderr, "Error: infinite loop terminated\n");
  return 42;
}

移除了kill 9,增加了SIGCHLD信号处理: 用来处理其它子进程退出。