多进程退出的问题

 

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

int run = 1;

//这里没有执行
void waitChild(int signo)
{
int status;
int pid;
while( ( pid = waitpid(-1, &status, 0 ) ) > 0)
{
printf( "44444child exist pid=%d \n" , pid );
}
printf( "555waitChild End \n");
}

void exitChild( int signo )
{
if( signo == SIGTERM )
{
printf( "2222child recv sig term pid=%d \n" , getpid() );
run = 0;
}
}

void worker()
{
signal(SIGTERM , exitChild );
signal(SIGINT , exitChild );

while( run == 1 )
{
printf("worker running pid=%d...\n" , getpid() );
sleep( 1 );
}
printf( "3333worker exit pid=%d \n" , getpid() );
exit( 0 );
}

void killChild( int signo )
{
if( signo == SIGINT )
{
printf( "1111kill child \n");
kill( 0 , SIGTERM );
}
}

int main()
{

int i;
pid_t pid;

signal(SIGCHLD, waitChild );
signal(SIGINT , killChild );
//子进程退出时触发

for(i=0; i<3; i++)
{
pid = fork();
if(pid == 0)
{
//child process
worker();
}
}

if(pid>0) {
printf("press Enter to exit...");
getchar();
}
return 0;
}

 

　

只执行了123 步，4，5没有触发,

SIGCHLD 应该在子进程退出时，触发，但是没有触发。


为了证明SIGCHLD确实可以触发，进行一下修改,子进程sleep(4)后，退出并触发了waitChild , 为什么上面的没有触发。

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

int run = 1;
//这里执行了
void waitChild(int signo)
{  
      int status;
      int pid;  
      while( ( pid = waitpid(-1, &status, 0 ) ) > 0)
      {
             printf(  "44444child exist pid=%d \n" , pid );
      }
    printf( "555waitChild End \n");
}  
   
void exitChild( int signo )
{
   if( signo == SIGTERM )
   {
      printf( "2222child recv sig term pid=%d \n" , getpid() );
      run = 0;
   }
}

void worker()
{
  signal(SIGTERM , exitChild );
  signal(SIGINT ,  exitChild );

  while( run == 1 )
  {
    printf("worker running pid=%d...\n" , getpid() );
    sleep( 4 );
    exit( 0 );
  }
  printf( "3333worker exit pid=%d \n" , getpid() );
}

void killChild( int signo )
{
   if( signo == SIGINT )
   {
      printf( "1111kill child \n");
      kill( 0 , SIGTERM );
   }
}

int main()
{  
   
  int i;  
  pid_t pid;  
 
  signal(SIGCHLD, waitChild ); 
  //子进程退出时触发

  for(i=0; i<3; i++)
  {  
    pid = fork();  
    if(pid == 0)
    {
     //child process 
        worker();
    }
  }  
  
  
  if(pid>0) { 
    printf("press Enter to exit...");  
    getchar();  
  }     
  return 0;  
}