C# 如何正确处理任务异常

我试图找出如何正确处理任务中的某些异常：

Task<Branch3GInfo> getActive3GRoutersTask = 
    Task.Run(
        () => CAS.Service.GetBranch3GInformationAsync(3)
    );

try
{
    Task.WaitAll(discoverRouterExtendedInfoTask, getActive3GRoutersTask);
}
catch(AggregateException aggEx)
{
    StringBuilder sb = new StringBuilder();
    sb.Append("Some problems occured on GetNodesInCriticalCondition(): \n");
    foreach (var ex in aggEx.InnerExceptions)
    {
        sb.Append(ex.Message);
    }

    Trace.TraceError(sb.ToString());
}

var branch3gInfo = getActive3GRoutersTask.Result;

调用方法：

Task<Branch3GInfo> getActive3GRoutersTask = 
    Task.Run(
        () => CAS.Service.GetBranch3GInformationAsync(3)
    );

try
{
    Task.WaitAll(discoverRouterExtendedInfoTask, getActive3GRoutersTask);
}
catch(AggregateException aggEx)
{
    StringBuilder sb = new StringBuilder();
    sb.Append("Some problems occured on GetNodesInCriticalCondition(): \n");
    foreach (var ex in aggEx.InnerExceptions)
    {
        sb.Append(ex.Message);
    }

    Trace.TraceError(sb.ToString());
}

var branch3gInfo = getActive3GRoutersTask.Result;

根据我的代码，我假设GetBranch3GInformationAsync应该执行else子句，该子句不会将结果添加到ActiveRoutersExpireFos，或者，它应该捕获异常。如果我在GetBranch3GInformationAsync中处理这个问题，为什么调用方法会抛出System.AggregateException

Task<Branch3GInfo> getActive3GRoutersTask = 
    Task.Run(
        () => CAS.Service.GetBranch3GInformationAsync(3)
    );

try
{
    Task.WaitAll(discoverRouterExtendedInfoTask, getActive3GRoutersTask);
}
catch(AggregateException aggEx)
{
    StringBuilder sb = new StringBuilder();
    sb.Append("Some problems occured on GetNodesInCriticalCondition(): \n");
    foreach (var ex in aggEx.InnerExceptions)
    {
        sb.Append(ex.Message);
    }

    Trace.TraceError(sb.ToString());
}

var branch3gInfo = getActive3GRoutersTask.Result;

我如何着手解决这个问题，以便忽略由于异常而失败的对GetRouterExtendedInfoFromInterfaceAsync的任何调用，并且不会破坏我的代码

Task<Branch3GInfo> getActive3GRoutersTask = 
    Task.Run(
        () => CAS.Service.GetBranch3GInformationAsync(3)
    );

try
{
    Task.WaitAll(discoverRouterExtendedInfoTask, getActive3GRoutersTask);
}
catch(AggregateException aggEx)
{
    StringBuilder sb = new StringBuilder();
    sb.Append("Some problems occured on GetNodesInCriticalCondition(): \n");
    foreach (var ex in aggEx.InnerExceptions)
    {
        sb.Append(ex.Message);
    }

    Trace.TraceError(sb.ToString());
}

var branch3gInfo = getActive3GRoutersTask.Result;

更新： System.AggregateException中InnerException的堆栈跟踪远程服务器返回错误：500内部服务器错误

Task<Branch3GInfo> getActive3GRoutersTask = 
    Task.Run(
        () => CAS.Service.GetBranch3GInformationAsync(3)
    );

try
{
    Task.WaitAll(discoverRouterExtendedInfoTask, getActive3GRoutersTask);
}
catch(AggregateException aggEx)
{
    StringBuilder sb = new StringBuilder();
    sb.Append("Some problems occured on GetNodesInCriticalCondition(): \n");
    foreach (var ex in aggEx.InnerExceptions)
    {
        sb.Append(ex.Message);
    }

    Trace.TraceError(sb.ToString());
}

var branch3gInfo = getActive3GRoutersTask.Result;

at System.Net.HttpWebRequest.EndGetResponse(IAsyncResult asyncResult) 
at System.Threading.Tasks.TaskFactory`1.FromAsyncCoreLogic(IAsyncResult iar, Func`2 endFunction, Action`1 endAction, Task`1 promise, Boolean requiresSynchronization)
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
at CASpectrumApi.CasApiRestCall.<ExecuteAsync>d__38.MoveNext() in C:\src\CASpectrumApi\src\CASpectrumApi\Queries\CasApiRestCall.cs:line 294
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
at CASpectrumApi.Managers.CasApiServiceManager.<RenderAndExecuteRestCallAsync>d__103.MoveNext() in C:\src\CASpectrumApi\src\CASpectrumApi\Managers\CasApiServiceManager.cs:line 2516
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
at CASpectrumApi.Managers.CasApiServiceManager.<QueryModelsFilterByAttributeNotDeviceOnlyAsync>d__51.MoveNext() in C:\src\CASpectrumApi\src\CASpectrumApi\Managers\CasApiServiceManager.cs:line 1196
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
at CASpectrumApi.Managers.CasApiServiceManager.<GetBranch3GInterfacesAsync>d__34.MoveNext() in C:\src\CASpectrumApi\src\CASpectrumApi\Managers\CasApiServiceManager.cs:line 442
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
at CASpectrumApi.Managers.CasApiServiceManager.<GetBranch3GInformationAsync>d__26.MoveNext() in C:\src\CASpectrumApi\src\CASpectrumApi\Managers\CasApiServiceManager.cs:line 246

---

您可以从调用堆栈中看到：

Task<Branch3GInfo> getActive3GRoutersTask = 
    Task.Run(
        () => CAS.Service.GetBranch3GInformationAsync(3)
    );

try
{
    Task.WaitAll(discoverRouterExtendedInfoTask, getActive3GRoutersTask);
}
catch(AggregateException aggEx)
{
    StringBuilder sb = new StringBuilder();
    sb.Append("Some problems occured on GetNodesInCriticalCondition(): \n");
    foreach (var ex in aggEx.InnerExceptions)
    {
        sb.Append(ex.Message);
    }

    Trace.TraceError(sb.ToString());
}

var branch3gInfo = getActive3GRoutersTask.Result;

at CASpectrumApi.Managers.CasApiServiceManager.<GetBranch3GInterfacesAsync>d__34.MoveNext()

---

失败的是对GetBranch3GInterfacesAsync的调用，而不是对GetRouterExtendedInfoFromInterfaceAsync的调用。GetBranch3GInterfacesAsync在try块外调用，因此异常自然会传播。

您看到的AggregateException的异常详细信息是什么？您的方法没有处理所有异常。假设branch3gInfo为null。您将获得NRE，然后将其传播到调用方法。有关详细信息，请参阅AggregateException.InnerExceptions属性。@StephenCleary它包含一个InnerException，表示HTTP调用返回HTTP 500内部服务器错误。我已经更新了堆栈跟踪的问题。调用方法try{Task.WaitAlldiscoverRouterExtendedInfoTask，getactive3groutrstask；}中的try/catch不应该捕获异常吗？@blgrnboy：它将在那里引发，如果调用getactive3groutrstask.Result，它将重新引发。

Task<Branch3GInfo> getActive3GRoutersTask = 
    Task.Run(
        () => CAS.Service.GetBranch3GInformationAsync(3)
    );

try
{
    Task.WaitAll(discoverRouterExtendedInfoTask, getActive3GRoutersTask);
}
catch(AggregateException aggEx)
{
    StringBuilder sb = new StringBuilder();
    sb.Append("Some problems occured on GetNodesInCriticalCondition(): \n");
    foreach (var ex in aggEx.InnerExceptions)
    {
        sb.Append(ex.Message);
    }

    Trace.TraceError(sb.ToString());
}

var branch3gInfo = getActive3GRoutersTask.Result;