c - timer_settime calling handler function in pthread on uClinux -

i've got following function gets called pthread_create. function work, sets timer, other work , waits timer expire before doing loop again. however, on first run of timer, after expires program quits , i'm not totally sure why. should never leave infinite while loop. main thread accesses nothing thread , vice versa (for now).

my guess might not have setup correctly thread, or timer not calling handler function correctly. perhaps changing idle global variable thread causes problem.

i call handler without signals, hence use of sigev_thread_id. i'm using sigusrx signals in main thread anyway. thoughts i've started here wrong?

#ifndef sigev_notify_thread_id #define sigev_notify_thread_id _sigev_un._tid #endif  volatile sig_atomic_t idle = 0; timer_t timer_id; struct sigevent sev;  void handler() {     printf("timer expired.\n");     idle = 0; }  void *thread_worker() {     struct itimerspec ts;      /* setup handler timer event */     memset (&sev, 0, sizeof(struct sigevent));     sev.sigev_notify = sigev_thread_id;     sev.sigev_value.sival_ptr = null;     sev.sigev_notify_function = handler;     sev.sigev_notify_attributes = null;     sev.sigev_signo = sigrtmin + 1;     sev.sigev_notify_thread_id = syscall(sys_gettid);      /* setup "idle" timer */     ts.it_value.tv_sec = 55;     ts.it_value.tv_nsec = 0;     ts.it_interval.tv_sec = 0;     ts.it_interval.tv_nsec = 0;      if (timer_create(0, &sev, &timer_id) == -1) {         printf("timer_create failed: %d: %s\n", errno, strerror(errno));         exit(3);     }      while (1) {         // work here before timer gets started takes 5 seconds          while (idle);   /* wait here until timer_id expires */          /* setup timer */         if (timer_settime(timer_id, 0, &ts, null) == -1) {             printf("timer_settime failed: %d\n", errno);             exit(3);         }          idle = 1;          // work here while timer running not take 10 seconds     } } 

as far can tell, haven't installed signal handler sigusr1, default action kills process when it's acted upon.

in case, whole thing strikes me extraordinarily bad design:

1. the while loop give 100% cpu load while waiting timer expire.

2. this not way use sigev_thread_id, , in fact sigev_thread_id isn't setup usable applications. rather it's libc use internally implementing sigev_thread.

3. you don't want using signals. they're messy.

if have threads, why aren't calling clock_nanosleep in loop? timers useful when can't this, e.g. when can't use threads.