我正在尝试学习进程和线程间的信号处理。回答以下几个问题会帮助我更好地理解它。
我知道一个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，但我不确定线程是否也是如此。
- 发往所有pthread的信号能否由超过一个pthread同时处理？
我使用 pthread_sigmask() 设置程序来阻止所有信号，我有两个线程使用 sigwait(SIGUSR1) 等待信号，而主线程则发送SIGUSR1信号。当只有一个线程处理信号时，似乎一切正常（我注释掉了另一个线程的代码），但当两个线程都运行 sigwait() 代码时，它就会挂起或过快终止。
以下是代码：
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;
}