junit java单元测试测试多线程并发方法详解编程语言

下面方法摘录自 http://www.planetgeek.ch/2009/08/25/how-to-find-a-concurrency-bug-with-java/， 用来测试多线程并发执行的方法。

public static void assertConcurrent(final String message, final List<? extends Runnable> runnables, final int maxTimeoutSeconds) throws InterruptedException { 
  final int numThreads = runnables.size(); 
  final List<Throwable> exceptions = Collections.synchronizedList(new ArrayList<Throwable>()); 
  final ExecutorService threadPool = Executors.newFixedThreadPool(numThreads); 
  try { 
    final CountDownLatch allExecutorThreadsReady = new CountDownLatch(numThreads); 
    final CountDownLatch afterInitBlocker = new CountDownLatch(1); 
    final CountDownLatch allDone = new CountDownLatch(numThreads); 
    for (final Runnable submittedTestRunnable : runnables) { 
      threadPool.submit(new Runnable() { 
        public void run() { 
          allExecutorThreadsReady.countDown(); 
          try { 
            afterInitBlocker.await(); 
            submittedTestRunnable.run(); 
          } catch (final Throwable e) { 
            exceptions.add(e); 
          } finally { 
            allDone.countDown(); 
          } 
        } 
      }); 
    } 
    // wait until all threads are ready 
    assertTrue("Timeout initializing threads! Perform long lasting initializations before passing runnables to assertConcurrent",  
        allExecutorThreadsReady.await(runnables.size() * 10, TimeUnit.MILLISECONDS)); 
    // start all test runners 
    afterInitBlocker.countDown(); 
    assertTrue(message +" timeout! More than " + maxTimeoutSeconds + " seconds", allDone.await(maxTimeoutSeconds, TimeUnit.SECONDS)); 
  } finally { 
    threadPool.shutdownNow(); 
  } 
  assertTrue(message + " failed with exception(s) " + exceptions, exceptions.isEmpty()); 
}

此方法接受三个参数：分别为错误消息， 并发执行的Runner列表，以及并发执行的超时时间。

方法中会启用一个线程池， 并将参数中的所有的Runner都准备好后并发执行runner方法， 并将所有的执行异常存放在一个list中， 如果方法在规定时间内执行完， 并且异常列表为空的情况认为方法正确执行。