pthreads之间的信号处理

Question

我想了解进程和线程之间的信号处理。几个问题的答案会帮助我更好地理解它。

我知道一个进程可以发送一个信号给进程组，并允许多个进程接收相同的信号，但我不确定线程​​。

• 发送给所有pthreads的信号是否可以同时由多个pthread处理？

设置我的计划，以阻止使用pthread_sigmask()所有信号，我有两个线程使用sigwait(SIGUSR1)等待信号，和我有主线程发送SIGUSR1信号。当只有一个线程处理信号时（我将其中的代码注释掉），似乎一切运行良好，但是当两者都运行sigwait()代码时，它会挂起或终止得太快。

代码粘贴在下面。

sig_atomic_t signals = 0; 
sig_atomic_t sigusr1_signals = 0; 
sig_atomic_t sigusr2_signals = 0; 
sig_atomic_t count = 0; 
sig_atomic_t totalcount = 0; 

sigset_t globalset; 

int WAIT = 1;   /* false = 0, true = 1 */ 

static int SIGNALS_SENT = 0; 
static int SIGNALS_RECEIVED = 0; 

void *sig1handler1(void *argv); 

void *reporterhandler(void *argv); 

int random_number(int min, int max); 

int main(void) { 

    pthread_t threads[2]; /* create an array to store a number of threads */ 

    //int *p_status = &status; 
    sigfillset(&globalset); 
    pthread_sigmask(SIG_BLOCK, &globalset, NULL); 

    /* Generate signal handling threads */ 
    if (pthread_create(&threads[0], NULL, &sig1handler1, NULL) > 0) 
    { 
     printf("Thread creation failure!\n"); 
     return -1; 
    } 


    /* create reporting thread */ 
    if (pthread_create(&threads[1], NULL, &reporterhandler, NULL) > 0) 
    { 
     printf("Thread creation failure!\n"); 
     return -1; 
    } 

    /* Signal all threads to begin work concurrently */ 
    WAIT = 0; 

    int c = 0; 
    while(c < 100) 
    { 
     int value = random_number(1, 2); 
     if (value == 1) 
      kill(0, SIGUSR1); 
     else 
      kill(0, SIGUSR2); 

     SIGNALS_SENT++; 
     c++; 
     usleep(10000); 
    } 

    kill(0, SIGINT); 


    /* Wait for each thread to finish and join */ 
    int i = 0; 
    for(i = 0; i < 2; i++) 
    { 
     if (pthread_join(threads[i], NULL) > 0) 
     { 
      printf("Thread [%u] join failure!\n", (unsigned int)threads[i]); 
      return -1; 
     } 

     printf("THREAD [%u] returned.\n", (unsigned int)threads[i]); 
    } 

    printf("Parent Process [%d] exiting successfully.\n", getpid()); 
    return EXIT_SUCCESS; 
} 


void *sig1handler1(void *argv) 
{ 
    pthread_t tid = pthread_self(); 
    printf("THREAD[%u] sig1handler1: waiting for signal to do some work...\n", (unsigned int)tid); 

// sigset_t myset; 
// sigfillset(&myset); 
// sigdelset(&myset, SIGINT); 
// sigdelset(&myset, SIGUSR1); 
// pthread_sigmask(SIG_SETMASK, &myset, NULL); 

    /* Wait for a signal to start work */ 
    while (WAIT); 

    int sig; 
    int count = 0; 

    while(1) 
    { 
     sigwait(&globalset, &sig); 
     if (sig == SIGUSR1) 
     { 
      sigusr1_signals++; 
      signals++; 
      count++; 
      //printf("thread1: caught SIGUSR1 signal!\n"); 
     } 
     else if (sig == SIGINT) 
     { 
      printf("thread1: caught SIGINT signal, detected SIGUSR1 %d times, and terminating!\n", count);   pthread_exit(NULL); 
     } 
    } 

    //printf("THREAD[%u] sig1handler1: doing some work!\n", (unsigned int)tid); 
    //return (void *)EXIT_SUCCESS; 
    //return (void *)NULL; 
    pthread_exit(NULL); 
} 

void *reporterhandler(void *argv) 
{ 
    pthread_t tid = pthread_self(); 
    printf("THREAD[%u] reporter: waiting for signal to do some work...\n", (unsigned int)tid); 

    int sig; 
    int count = 0; 

// sigset_t myset; 
// sigfillset(&myset); 
// sigdelset(&myset, SIGINT); 
// sigdelset(&myset, SIGUSR1); 
// sigdelset(&myset, SIGUSR2); 
// pthread_sigmask(SIG_SETMASK, &myset, NULL); 

    /* Wait for a signal to start work */ 
    while (WAIT); 

    while(1) 
    { 
     sigwait(&globalset, &sig); 
     if (sig == SIGUSR1) 
     { 
      sigusr1_signals++; 
      signals++; 
      count++; 
      totalcount++; 
      SIGNALS_RECEIVED++; 
     } 
     else if (sig == SIGUSR2) 
     { 
      sigusr2_signals++; 
      signals++; 
      count++; 
      totalcount++; 
      SIGNALS_RECEIVED++; 
     } 
     else if (sig == SIGINT) 
     { 
      printf("Reporter: SIGUSR1 detected %d times\n", sigusr1_signals); 
      printf("Reporter: SIGUSR2 detected %d times\n", sigusr2_signals); 
      printf("Reporter: detected %d signals\n", totalcount); 
      printf("Reporter: SIGNALS_SENT %d \n", SIGNALS_SENT); 
      printf("Reporter: SIGNALS_REC %d \n", SIGNALS_RECEIVED); 
      pthread_exit(NULL); 
     } 

     /* Display Report after detecting 10 signals */ 
     if (count == 10) 
        sigusr1_signals, sigusr2_signals); 

      count = 0; 
     } 
    } 

    //printf("THREAD[%u] reporter: doing some work!\n", (unsigned int)tid); 
    pthread_exit(NULL); 
} 

int random_number(int min, int max) 
{ 
    if (min < max) 
    { 
     max = max + 1;  /* include the max value */ 
     return (rand() % (max - min)) + min; 
    } 

    return -1; 
} 

Answer 1

• 能信号[被]发送至[和]可以由多于一个的并行线程在同一时间处理的所有并行线程？

不是在同一时间。这些都是可能性：

1. 发送信号的过程（kill()）：在这种情况下，任何线程监听信号，可以接收，但只有一个会做到这一点。
2. 向进程组发送信号：信号将被传送到组中的所有进程。
3. 发送信号到特定线程（pthread_kill()）：现在您将它发送到特定线程ID。

原型：

int pthread_kill(pthread_t thread, int sig); 

在你的情况，我认为该信号传递给所有线程的唯一方法就是沿着所有的线程ID迭代与pthread_kill()发送信号。