对于多线程编程时候，对于signal传递的信号处理函数对于各个线程是共享的，虽然各个线程可以设置自己的屏蔽字。如下面所示代码。两个线程中，每个线程有一个signal接受信号，但是实际上执行时每个线程会执行两个signal信号处理函数。

也可以用  pthread_sigmask(SIG_SETMASK, &set, NULL);设置自己线程的屏蔽字，不接收某个信号。注意：：如果没有设置屏蔽字，并且也没有设置signal函数接收SIGUSR1与

SIGUSR12时，用kill发送信号会导致进程直接退出。

#include #include

#include #include #include

void thread_handler_first();

void thread_handler_second();

void sign_handler(int sign);

int main()

{

pthread_t thread_first, thread_second;

if(pthread_create(&thread_first, NULL, (void *)*thread_handler_first, NULL) != 0)

{

printf("create child thread fail\n"); exit(EXIT_FAILURE);

}

else

printf("create first child thread success\n");

if(pthread_create(&thread_second, NULL, (void *)*thread_handler_second, NULL) != 0)

{

printf("create child thread fail\n"); exit(EXIT_FAILURE);

}

else

printf("create second child thread success\n");

sleep(2);

printf("Now the main thread prepare to send SIGUSR1 and SIGUSR2 to first child thread\n");

if(pthread_kill(thread_first, SIGUSR1) || pthread_kill(thread_first, SIGUSR2))

{

printf("send SIGUSR1 and SIGUSR2 to first child thread fail\n"); exit(EXIT_FAILURE);

}

else

printf("send SIGUSR1 and SIGUSR2 to first child thread success\n");

sleep(1);

printf("Now the main thread prepare to send SIGUSR1 and SIGUSR2 to second child thread\n");

if(pthread_kill(thread_second, SIGUSR1) || pthread_kill(thread_second, SIGUSR2))

{

printf("send SIGUSR1 and SIGUSR2 to second child thread fail\n"); exit(EXIT_FAILURE);

}

else

printf("send SIGUSR1 and SIGUSR2 to second child thread success\n");

sleep(1);

printf("Now the main thread prepare to send SIGKILL to both first and second child thread\n");

if(pthread_kill(thread_first, SIGKILL) != 0)

{

printf("send SIGKILL to first child thread fail\n"); exit(EXIT_FAILURE);

}

else

printf("send SIGKILL to first child thread success\n");

if(pthread_kill(thread_first, SIGKILL) != 0)

{

printf("send SIGKILL to second child thread fail\n"); exit(EXIT_FAILURE);

}

else

printf("send SIGKILL to second child thread success\n");

sleep(1);

pthread_join(thread_first, NULL);

pthread_join(thread_second, NULL);

exit(EXIT_SUCCESS);

}

void thread_handler_first()

{

int i;

__sigset_t set;

signal(SIGUSR1, sign_handler);

sigfillset(&set);

sigdelset(&set, SIGUSR1);

sigdelset(&set, SIGUSR2);

pthread_sigmask(SIG_SETMASK, &set, NULL);

for(i = 0; i < 5; i++)

{

printf("this is first thread:%u...\n", pthread_self()); pause();

}

}

void thread_handler_second()

{

int i;

signal(SIGUSR2, sign_handler);

//    signal(SIGUSR1, sign_handler);

for(i = 0; i < 5; i++)

{

printf("This is second thread:%u...\n",pthread_self()); pause();

}

}

void sign_handler(int sign)

{

printf("\nthread:%u, receive signal:%u---\n", pthread_self(), sign);

}

执行结果如下：

create first child thread success

create second child thread success

This is second thread:3069864816...

this is first thread:3078257520...

Now the main thread prepare to send SIGUSR1 and SIGUSR2 to first child thread

send SIGUSR1 and SIGUSR2 to first child thread success

thread:3078257520, receive signal:12---

thread:3078257520, receive signal:10---

this is first thread:3078257520...

Now the main thread prepare to send SIGUSR1 and SIGUSR2 to second child thread

send SIGUSR1 and SIGUSR2 to second child thread success

thread:3069864816, receive signal:12---

thread:3069864816, receive signal:10---

This is second thread:3069864816...

Now the main thread prepare to send SIGKILL to both first and second child thread

Killed