9

我目前遇到 IIS 崩溃的问题，在事件日志中留下以下消息。它们在将我引导到错误的实际来源方面并没有太大帮助，但一些研究表明这只是产生任务但不等待结果的情况，如果父进程完成，它们最终会完成它不能与导致空引用异常的父线程相关联。那是对的吗？

在大多数情况下，我已经删除或添加了等待发生的地方，但有些地方很方便。一个这样的例子是在会话开始时，内存缓存了会话特有的一些细节，但是它们并不是立即重要的，所以我启动了一项任务来完成这项工作，但不要等待它。

我已经添加了 ConfigureAwait(false)，这足以防止将来出现错误吗？听起来这将删除我认为可以防止错误的线程切换。

Task.Run(() =>
{
    // Do caching here

}).ConfigureAwait(false);

ASP.NET 4.0.30319.0

Exception: System.NullReferenceException

Message: Object reference not set to an instance of an object.

StackTrace:    at System.Web.ThreadContext.AssociateWithCurrentThread(Boolean setImpersonationContext)
   at System.Web.HttpApplication.OnThreadEnterPrivate(Boolean setImpersonationContext)
   at System.Web.LegacyAspNetSynchronizationContext.CallCallbackPossiblyUnderLock(SendOrPostCallback callback, Object state)
   at System.Web.LegacyAspNetSynchronizationContext.CallCallback(SendOrPostCallback callback, Object state)
   at System.Threading.Tasks.AwaitTaskContinuation.RunCallback(ContextCallback callback, Object state, Task& currentTask)
--- End of stack trace from previous location where exception was thrown ---
   at System.Threading.Tasks.AwaitTaskContinuation.<ThrowAsyncIfNecessary>b__1(Object s)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.QueueUserWorkItemCallback.System.Threading.IThreadPoolWorkItem.ExecuteWorkItem()
   at System.Threading.ThreadPoolWorkQueue.Dispatch()

.NET 运行时

Application: w3wp.exe
Framework Version: v4.0.30319
Description: The process was terminated due to an unhandled exception.
Exception Info: System.NullReferenceException
Stack:
   at System.Threading.Tasks.AwaitTaskContinuation.<ThrowAsyncIfNecessary>b__1(System.Object)
   at System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object, Boolean)
   at System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object, Boolean)
   at System.Threading.QueueUserWorkItemCallback.System.Threading.IThreadPoolWorkItem.ExecuteWorkItem()
   at System.Threading.ThreadPoolWorkQueue.Dispatch()

应用程序错误

Faulting application name: w3wp.exe, version: 7.5.7601.17514, time stamp: 0x4ce7afa2
Faulting module name: KERNELBASE.dll, version: 6.1.7601.18015, time stamp: 0x50b8479b
Exception code: 0xe0434352
Fault offset: 0x0000000000009e5d
Faulting process id: 0x1d98
Faulting application start time: 0x01ceaf8ea10ece66
Faulting application path: c:\windows\system32\inetsrv\w3wp.exe
Faulting module path: C:\Windows\system32\KERNELBASE.dll
Report Id: 341b9a76-1b82-11e3-8e17-005056be0005
4

1 回答 1

6

经过一上午的时间追逐这个问题，我最终发现有一条路径可以让父母绕过造成这个问题的等待。快速重构以防止这种情况解决了问题。

在最简单的形式中，导致问题的代码大致如下：

var getDataTask = getData();

if(some_condition == true) {
    return some_object;
}

getDataTask.Wait();

return getDataTask.result;

如果some_condition == true该方法将返回而不等待getDataTask完成。重构以停止修复它。

于 2013-09-12T11:06:25.460 回答