BackgroundWorker阻塞问题-集成测试和实际应用之间的不一致

我遇到了一个奇怪的情况。我试图使用BackgroundWorker实例列表，在它们上调用RunWorkerAsync()，然后等待它们全部完成，然后返回对调用者的响应。当我从NUnit集成测试中调用该方法时，它运行得很好，该测试会执行worker中的所有代码。然而，当我从我的web应用程序执行，非常相同的代码不断阻塞主线程和RunWorkerCompleted回调从未触发。为什么会这样?以下是我的代码(这里只使用1个BackgroundWorker来说明，但我只在实际使用> 1时使用它):

创建BackgroundWorkers并以阻塞方式执行它们的主代码:

// Build a list of BackgroundWorker instances representing the work needing to be done
var workers = new List<BackgroundWorker>
{
    GetContactsByFullNameAsync(lastName, firstName),
};
// Execute the work to be done (blocking during execution)
this.ExecuteAsyncWork(workers);
// Aggregate up the contacts and return the final result
return this.AggregateContacts(result);

新建一个BackgroundWorker的私有函数(但不执行它):

private BackgroundWorker GetContactsByFullNameAsync(string lastName, string firstName)
{
    var worker = new BackgroundWorker();
    worker.DoWork += (sender, args) =>
    {
        var result = new SuperSearchResultDTO();
        IList<Contact> contacts = _contactRepository.GetContactsByFullName(lastName, firstName);
        // Transform any resulting Contact instances to ContactDTO instances
        if (contacts != null && contacts.Count != 0)
            contacts.ToList().ForEach(c => result.Contacts.Add(ContactDTO.GetFromContact(c)));
        args.Result = result;
    };
    worker.RunWorkerCompleted += (sender, e) =>
    {
        if (e.Error != null)
            // An error was thrown inside the repository, but since it was thrown in a separate thread, it 
            // won't stop the current thread from executing as per usual.  We need to log the exception with 
            // the results, and handle it later.  Throwing right here doesn't do anything.
            _asyncWork[source] = new SuperSearchResultDTO { Exception = e.Error };
        else if (e.Cancelled)
            _asyncWork[source] = new SuperSearchResultDTO { Exception = new Exception("GetSSOContactsByEmailAsync was cancelled") };
        else
            // Cast the results from type "object" to SuperSearchResultDTO
            _asyncWork[source] = (SuperSearchResultDTO)e.Result;
    };
    return worker;
}

私有方法，用于执行所有worker，阻塞直到完成并处理异常:

private void ExecuteAsyncWork(List<BackgroundWorker> workers)
{
    // Kick of the searches against the different data sources simultaneously
    workers.ForEach(x => x.RunWorkerAsync());
    // BLOCK the current thread until either all the async methods are complete 
    while (workers.Any(x => x.IsBusy))
        System.Threading.Thread.Sleep(50);
    // Handle any exceptions
    var exception = _asyncWork.Where(x => x.Value != null && x.Value.Exception != null).Select(x => x.Value.Exception).FirstOrDefault();
    if (exception != null)
        throw exception;
}