Hello list.
I am having problems using pthread conditional variables with mutexes
created using mutex attributes with the latest Cygwin. If I initialize
my mutexes with NULL attributes to get the default behavior, everything
works. However if I try to use mutex attributes my program freezes.
I am attaching a small test set written in C++ I devised to exhibit
the problem.
Has anyone faced the same trouble? Best regards.
--
PabloBleyerKocik /"The use of COBOL cripples the mind; its teaching
pablo / should, therefore, be regarded as a criminal
@bleyer.org / offense." -- Edsger Wybe Dijkstra
#include <pthread.h>
#include <string.h>
#include <iostream>
static pthread_mutex_t mutex;
static pthread_cond_t cond;
static bool quit = false;
void *
runner(void *p) {
struct timespec tv;
tv.tv_sec = 3;
tv.tv_nsec = 0;
std::cout << "Runner running..." << std::endl;
nanosleep(&tv, NULL);
std::cout << "Runner returning..." << std::endl;
pthread_mutex_lock(&mutex);
quit = true;
pthread_mutex_unlock(&mutex);
pthread_cond_broadcast(&cond);
return NULL;
}
void *
waiter(void *p) {
std::cout << "Waiter " << (int)p << " running..." << std::endl;
pthread_mutex_lock(&mutex);
while (!quit) pthread_cond_wait(&cond, &mutex);
pthread_mutex_unlock(&mutex);
std::cout << "Waiter " << (int)p << " returning..." << std::endl;
return NULL;
}
int
main(int argc, char **argv) {
pthread_t d, w1, w2;
#if 1 // Program freezes
pthread_mutexattr_t a;
pthread_mutexattr_init(&a);
pthread_mutexattr_settype(&a, PTHREAD_MUTEX_NORMAL);
pthread_mutex_init(&mutex, &a);
pthread_mutexattr_destroy(&a);
#else // This works
pthread_mutex_init(&mutex, NULL);
#endif
pthread_cond_init(&cond, NULL);
pthread_create(&d, NULL, runner, NULL);
pthread_create(&w1, NULL, waiter, (void *)1);
pthread_create(&w2, NULL, waiter, (void *)2);
pthread_join(d, NULL);
pthread_join(w1, NULL);
pthread_join(w2, NULL);
return 0;
}
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