fix multipurpose handling of SIGUSR1

src/signals-unix.c

@@ -539,9 +539,13 @@ JL_DLLEXPORT int jl_profile_start_timer(void)
 
 JL_DLLEXPORT void jl_profile_stop_timer(void)
 {
- if (running)
+ if (running) {
  timer_delete(timerprof);
- running = 0;
+ // Because SIGUSR1 is multipurpose, care must be taken for running = 0 to be set after the timer has fully stopped.
+ // There may be a pending signal emitted from the timer so wait a few timer cycles
+ sleep_ms((nsecprof / GIGA) * 1000 * 3);
+ running = 0;
+ }
 }
 
 #elif defined(HAVE_ITIMER)
@@ -556,18 +560,24 @@ JL_DLLEXPORT int jl_profile_start_timer(void)
  timerprof.it_interval.tv_usec = 0;
  timerprof.it_value.tv_sec = nsecprof / GIGA;
  timerprof.it_value.tv_usec = ((nsecprof % GIGA) + 999) / 1000;
- if (setitimer(ITIMER_PROF, &timerprof, NULL) == -1)
- return -3;
+ // Because SIGUSR1 is multipurpose, set `running` before so that we know that the first SIGUSR1 came from the timer
  running = 1;
+ if (setitimer(ITIMER_PROF, &timerprof, NULL) == -1) {
+ running = 0;
+ return -3;
+ }
  return 0;
 }
 
 JL_DLLEXPORT void jl_profile_stop_timer(void)
 {
  if (running) {
- running = 0;
  memset(&timerprof, 0, sizeof(timerprof));
  setitimer(ITIMER_PROF, &timerprof, NULL);
+ // Because SIGUSR1 is multipurpose, care must be taken for running = 0 to be set after the timer has fully stopped.
+ // There may be a pending signal emitted from the timer so wait a few timer cycles
+ sleep_ms((nsecprof / GIGA) * 1000 * 3);
+ running = 0;
  }
 }