我遇到了一个奇怪的情况。我尝试使用BackgroundWorker实例列表,在它们上调用RunWorkerAsync(),然后在将响应返回给调用者之前等待所有这些实例完成。当我从NUnit集成测试中调用该方法时,这种方法很有效,该测试可以运行worker中的所有代码。但是,当我从我的Web应用程序执行时,相同的代码会不断阻塞主线程,并且RunWorkerCompleted回调永远不会触发。为什么是这样?这是我的代码(这里仅使用1个BackgroundWorker来说明,但我实际上只有> 1时才使用它):
为BackgroundWorkers提供新闻并以阻止方式执行它们的主要代码:
// 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);
用于新建BackgroundWorker的私有功能(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;
}
执行所有工作程序的私有方法,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;
}
答案 0 :(得分:1)
你只是在主线程上调用Thread.Sleep
,所以它会阻塞。您需要使用回调或事件来解决此问题。