static new MultiSet<S> poorMansProfiling_results;
static int poorMansProfiling_samples;
static java.util.Timer poorMansProfiling_timer;
static Lock poorMansProfiling_lock = lock();
static Thread poorMansProfiling_threadToSample; // otherwise sample all threads

static void poorMansProfiling() {
  poorMansProfiling(poorMansProfiling_defaultInterval());
}

static void poorMansProfiling(Thread thread) {
  poorMansProfiling(poorMansProfiling_defaultInterval(), thread);
}

static void poorMansProfiling(int interval) {
  poorMansProfiling(interval, null);
}

static void poorMansProfiling(int interval, Thread thread) {
  lock poorMansProfiling_lock;
  poorMansProfiling_threadToSample = thread;
  poorMansProfiling_stop();
  poorMansProfiling_clear();
  poorMansProfiling_timer = doEvery_daemon(interval, r {
    Map<Thread, StackTraceElement[]> map =
      poorMansProfiling_threadToSample != null
        ? litmap(poorMansProfiling_threadToSample, poorMansProfiling_threadToSample.getStackTrace())
        : runnableThreadsWithStackTraces();
    lock poorMansProfiling_lock;
    poorMansProfiling_samples++;
    for (Thread t : keys(map)) {
      continue if isSystemThread(t);
      new StringBuilder buf;
      for (StackTraceElement e : map.get(t))
        buf.append(e).append("\n");
      poorMansProfiling_results.add(str(buf));
    }
  });
}

static void poorMansProfiling_stop() {
  lock poorMansProfiling_lock;
  if (poorMansProfiling_timer != null) {
    stopTimer(poorMansProfiling_timer);
    poorMansProfiling_timer = null;
  }
}

static void poorMansProfiling_clear() {
  lock poorMansProfiling_lock;
  poorMansProfiling_results.clear();
  poorMansProfiling_samples = 0;
}

static MultiSet<S> poorMansProfiling_results() {
  ret new MultiSet(poorMansProfiling_results);
}

static MultiSet<S> poorMansProfiling_stopAndGetResults() {
  lock poorMansProfiling_lock;
  poorMansProfiling_stop();
  ret poorMansProfiling_results();
}