Hi guys, I’ve been trying to track down a bug with multi-thread use of libevent. I’m only using the timeout feature of libevent (no fd’s). I’ve dumbed down the issue to a simple example which is copied in below. This code deadlocks waiting for the event to occur. [ Psuedo Code ] <thread 1: main> * kicks of thread 2 * waits for other thread to alloc a base+event * adds event * waits for callback to occur (which never happens) * exits <thread 2> * alloc’s event base + event * dispatches Any idea’s why this doesn’t work? And yes I’ve called evthread_use_pthreads ;^) I’ve tried this on a Fedora 15 and OSX box with the same results. Although I tried with the package managed versions I also tried and got the same results with the trunk of the git tree, release-2.1.3-alpha-44-g197abd8 (on the Fedora box only). Regards, Dave Build the following with “gcc -Wall -o event-test main.c -lrt -levent -levent_pthreads” #include <stdio.h> #include <event.h> #include <pthread.h> #include <errno.h> #include <string.h> #include <unistd.h> #include <semaphore.h> #include <event2/thread.h> #include <fcntl.h> struct event_base* eb = NULL; struct event *ev = NULL; sem_t *sem; const struct timeval tv = { .tv_sec = 2, .tv_usec = 0 }; void cb_sem_post(evutil_socket_t fd, short val, void *arg) { printf("Running %s\n", __func__); sem_post(sem); } void *new_thread(void *arg) { printf("Running %s\n", __func__); /* initialize libevent */ if(evthread_use_pthreads()) { fprintf(stderr, "evthread_use_pthreads failed: %s\n", strerror(errno)); return 0; } eb = event_base_new(); ev = evtimer_new(eb, cb_sem_post, 0); if(!ev) fprintf(stderr, "evtimer_new failed: %s\n", strerror(errno)); sem_post(sem); /* ok free to use ev & eb from other thread */ event_base_dispatch(eb); return 0; } int main(int argc, const char * argv[]) { pthread_t thread; printf("Running %s\n", __func__); /* initialize a semaphore */ sem = sem_open("my_sem", O_CREAT, 0777, 0); if(sem == SEM_FAILED) { fprintf(stderr, "sem_open failed: %s\n", strerror(errno)); return 1; } if(pthread_create(&thread, NULL, new_thread, 0)) { fprintf(stderr, "%s\n", strerror(errno)); return 1; } sem_wait(sem); /* ev has been allocated */ //usleep(3000000); /* wait till other thread good and sleeping */ /* add event that will never expire */ if(event_add(ev, &tv)) fprintf(stderr, "%s\n", strerror(errno)); printf("waiting for callback that never occurs\n"); sem_wait(sem); printf("Exiting\n"); /* clean up */ event_base_loopexit(eb, NULL); if(ev) event_free(ev); if(eb) event_base_free(eb); pthread_join(thread, NULL); sem_close(sem); return 0; } _______________________________________________ Program output: Running main Running new_thread [debug] event_add: event: 0xb6f00618 (fd 7), EV_READ call 0xb788a7d3 [debug] Epoll ADD(1) on fd 7 okay. [old events were 0; read change was 1; write change was 0] [debug] event_base_loop: no events registered. [debug] event_add: event: 0xb6f00908 (fd -1), EV_TIMEOUT call 0x80489e0 [debug] event_add: event 0xb6f00908, timeout in 2 seconds 0 useconds, call 0x80489e0 waiting for callback that never occurs |