我正在使用 Linux 并尝试与信号处理相关的代码。按照我正在尝试的代码,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 );
}
即使我正在使用“ pthread_sigmask(SIG_BLOCK,&new_set,&old_set)”。它没有阻塞信号。但是如果我删除“pthread_create(&a, NULL, threadmasked, NULL);” 它工作正常并阻止信号。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。