Question

我正在尝试学习进程和线程之间的信号处理。几个问题的答案将帮助我更好地理解它。

我知道进程可以向进程组发送信号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pthread的信号是否可以同时由多个pthread处理？

我设置程序使用pthread_sigmask()来阻止所有信号，我有两个线程使用sigwait(SIGUSR1)来等待信号，我让主线程发送SIGUSR1信号。似乎只有一个线程处理信号时一切正常（我在另一个线程中注释掉了代码），但是当两个线程都在运行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

可以将信号发送到所有pthreads [和]同时由多个pthread处理吗？

不是在同一时间。这些是可能性：

向进程发送信号（kill()）：在这种情况下，任何侦听信号的线程都可以接收它，但只有一个可以接收它。
向进程组发送信号：信号将传递给组中的所有进程。
向特定线程（pthread_kill()）发送信号：现在您将其发送到特定线程ID。

原型：

int pthread_kill(pthread_t thread, int sig);

在您的情况下，我认为向所有线程传递信号的唯一方法是沿着所有线程ID迭代，以pthread_kill()发送信号。

pthreads之间的信号处理

1 个答案: