static Var<java.util.Timer> startDeadlockDetector_timer = new Var;
static int startDeadlockDetector_interval;
static bool startDeadlockDetector_noStop; // don't stop when deadlock found

static void startDeadlockDetector() {
  synchronized(startDeadlockDetector_timer) {
    if (startDeadlockDetector_timer! == null)
      startDeadlockDetector_timer.set(doEvery_daemon(1000, func {
        if (empty(printDeadlocks())) null;
        print("Stopping deadlock detector.");
        ret startDeadlockDetector_noStop ? null : false;
      }));
  }
}