svoid test_ThreadPool() {
  new ThreadPool pool;
  print(pool);
  flagTest(flag -> pool.acquireThread((Runnable) flag), 10.0);
  print(pool);
  
  int n = pool.maxSize()*2;
  new IntVar counter;
  new IntVar waitCounter;
  pool.onCustomerMustWaitAlert(-> inc(waitCounter));
  for immutable i to n: {
    var t = pool.acquireThread(r {
      sleepSeconds((i+1)*0.2);
      printWithMS(this + " done");
      inc(counter);
    });
    printWithMS("Acquired thread " + t);
  }
  counter.waitForValue(n);
  assertEquals(4, waitCounter!);
  print(pool);
}