() -> {
                  startLatch.countDown();
                  startLatch.await();
                  callable.call();
                  doneLatch.countDown();
                  return null;
                });
      }
      doneLatch.await();
    } finally {
      executorService.shutdown();
    }
  }

                    Thread.currentThread().interrupt();
                } finally {
                    doneLatch.countDown();
                }
            }).start();
        }

        startLatch.countDown();
        doneLatch.await();

        // Verify all items were polled exactly once
        assertEquals(itemsPerThread * numThreads, totalPolled.get());

                } catch (InterruptedException ignore) {} finally {
                    doneLatch.countDown();
                }
            }).start();
        }

        startLatch.countDown(); // Start all threads
        assertTrue("All threads should complete", doneLatch.await(10, TimeUnit.SECONDS));

        Thread.sleep(100); // Wait for callback to execute