我正在使用 Linux 并尝试与信号处理相关的代码。我正在尝试以下代码，但我无法理解此代码的行为。
/**Globally declared variable**/
time_t start, finish;
struct sigaction sact;
sigset_t new_set, old_set,test;
double diff;
/**Function to Catch Signal**/
void catcher( int sig )
{
cout<< "inside catcher() function\n"<<endl;
}
void Initialize_Signalhandler()
{
sigemptyset( &sact.sa_mask );
sact.sa_flags = 0;
sact.sa_handler = catcher;
sigaction( SIGALRM, &sact, NULL );
sigemptyset( &new_set );
sigaddset( &new_set, SIGALRM );
}
/**Function called by thread**/
void *threadmasked(void *parm)
{
/**To produce delay of 10sec**/
do {
time( &finish );
diff = difftime( finish, start );
} while (diff < 10);
cout<<"Thread Exit"<<endl;
}
int main( int argc, char *argv[] ) {
Initialize_Signalhandler();
pthread_t a;
pthread_create(&a, NULL, threadmasked, NULL);
pthread_sigmask( SIG_BLOCK, &new_set, &old_set);
time( &start );
cout<<"SIGALRM signals blocked at %s\n"<< ctime(&start) <<endl;
alarm(2); //to raise SIGALM signal
/**To produce delay of 10sec**/
do {
time( &finish );
diff = difftime( finish, start );
} while (diff < 10);
return( 0 );
}
甚至认为我正在使用“pthread_sigmask(SIG_BLOCK, &new_set, &old_set)”。它没有阻挡信号。但是如果我删除“pthread_create(&a, NULL, threadmasked, NULL);”它工作正常并阻止了信号。我在这里观察到的另一件事是，如果我将 pthread_sigmask 更改为 sigprocmask，行为保持不变。
最佳答案
线程从创建它们的线程继承信号掩码。
因此，当您的代码调用 pthread_sigmask() after 它调用 pthread_create() 时，新创建的线程不会修改其信号掩码.
像这样更改你的代码，让事情按你预期的那样工作:
...
pthread_sigmask( SIG_BLOCK, &new_set, &old_set);
pthread_t a;
pthread_create(&a, NULL, threadmasked, NULL);
...
关于c++ - pthread_sigmask :unusual behavior，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/14495192/