IIS 7.5应用程序池回收不让方法完成

Question

I have 2 methods:

public void Stop(bool immediate)
{
    Logger.Log(LogLevel.Debug, "Shutdown detected. Immediate: " + immediate);
    Shutdown();
    Logger.Log(LogLevel.Debug, "Unregistering");
    HostingEnvironment.UnregisterObject(this);
}

public void Shutdown()
{
    Logger.Log(LogLevel.Debug, "Preparing to stop UploadQueue");
    IsProcessing = false;

     //Set tasks to cancel to prevent queued tasks from parsing
     _cancellationTokenSource.Cancel();

     Logger.Log(LogLevel.Debug, "Waiting for " + _workerTasks.Count + " tasks to finish or cancel.");
     //Wait for tasks to finish
     Task.WaitAll(_workerTasks.Values.ToArray());

     Logger.Log(LogLevel.Debug, "Stopped UploadQueue");
}

The class is using the IRegisteredObject interface to receive the shutdown notification. In my log I get this:

2014-07-18 15:30:55,913,DEBUG,Shutdown detected. Immediate: False
2014-07-18 15:30:55,913,DEBUG,Preparing to stop UploadQueue
2014-07-18 15:30:55,913,DEBUG,Waiting for 35 tasks to finish or cancel.
...
bunch of stuff
...
2014-07-18 15:31:28,471,DEBUG,Shutdown detected. Immediate: True
2014-07-18 15:31:28,471,DEBUG,Preparing to stop UploadQueue
2014-07-18 15:31:28,471,DEBUG,Waiting for 0 tasks to finish or cancel.
2014-07-18 15:31:28,471,DEBUG,Stopped UploadQueue
2014-07-18 15:31:28,471,DEBUG,Unregistering

Why isn't it getting to the Logger.Log(LogLevel.Debug, "Stopped UploadQueue"); the first time? it certainly seems like its cancelling the tasks and letting the ones that are running finish. (The task checks if its cancelled before running, otherwise does it's thing).

Answer 1

From Task.WaitAll :

AggregationException:

At least one of the Task instances was canceled -or- an exception was thrown during the execution of at least one of the Task instances. If a task was canceled, the AggregateException contains an OperationCanceledException in its InnerExceptions collection.

You are cancelling your Tasks via _cancellationTokenSource.Cancel(); and i assume that is causing at least one of them to throw an exception. You might be catching it in a higher level stackframe and disregarding it. Wrap Task.WaitAll inside a try-catch block:

public void Shutdown()
{
    Logger.Log(LogLevel.Debug, "Preparing to stop UploadQueue");
    IsProcessing = false;

    //Set tasks to cancel to prevent queued tasks from parsing
    _cancellationTokenSource.Cancel();

    Logger.Log(LogLevel.Debug, "Waiting for " + _workerTasks.Count + " tasks to finish or cancel.");

     try
     {
         //Wait for tasks to finish
         Task.WaitAll(_workerTasks.Values.ToArray());

         Logger.Log(LogLevel.Debug, "Stopped UploadQueue");
     }
     catch (AggregationException e)
     {
         // Recover from the exception
     }
}