我有一个服务，遵循OnStart（）方法：
protected override void OnStart(string[] args)
{
this.manager.StartManager();
this.log.LogEvent(this.id.ToString(), string.Format(CultureInfo.InvariantCulture, "System"), string.Format(CultureInfo.InvariantCulture, "Service started"));
}
和OnStop（）方法：
protected override void OnStop()
{
this.manager.CancellationTokenSource.Cancel();
this.log.LogEvent(this.id.ToString(), string.Format(CultureInfo.InvariantCulture, "System"), string.Format(CultureInfo.InvariantCulture, "Service stopped"));
}
StartManager（）方法实现如下：
public void StartManager()
{
foreach (var reportGeneratorThread in this.ReportGenerators)
{
reportGeneratorThread.Start();
Thread.Sleep(1000);
}
try
{
Task.WaitAll(this.Tasks.ToArray());
}
catch (AggregateException e)
{
foreach (var v in e.InnerExceptions)
{
var taskException = v as TaskCanceledException;
if (v != taskException)
{
foreach (var reportGenerator in this.ReportGenerators)
{
if (reportGenerator.Task.IsFaulted)
{
this.logger.LogEvent(this.Id.ToString(), string.Format(CultureInfo.InvariantCulture, "System"), string.Format(CultureInfo.InvariantCulture, "Unhandled exception from Task " + reportGenerator.Task.Id));
ReportGeneratorThread faultedReportGeneratorThread = this.GetThreadById(reportGenerator.Task.Id);
var index = this.ReportGenerators.FindIndex(t => t.Equals(faultedReportGeneratorThread));
this.DisposeFaultedThread(faultedReportGeneratorThread, index);
this.ReportGenerators[index].Start();
this.logger.LogDebug(string.Format(CultureInfo.InvariantCulture, "Faulted Task, and instance of ReportGeneratorThread is recreated and corresponding task is started"));
break;
}
}
}
else if (taskException != null)
{
this.logger.LogEvent(this.Id.ToString(), string.Format(CultureInfo.InvariantCulture, "System"), string.Format(CultureInfo.InvariantCulture, "Task " + taskException.Task.Id + " has thrown a Task Canceled Exception"));
}
}
}
}
问题出现在我的StartManager（）方法中，因为reportGeneratorThread.Start（）方法正在启动一个任务，该任务在while循环中连续生成报告，只有在抛出取消令牌并且我才会被中止。 ;我把它扔在我的服务OnStop（）方法中。 因此，当我测试我的服务时，程序无法比Task.WaitAll（）更进一步，这阻止我完成OnStart（）方法，并且我收到以下错误：
Error 1053: the service did not respond to the start or control request in a timely fashion
我仍然需要管理我的任务，所以我实际上需要Task.WaitAll（）方法，但我也需要解决这个问题。在这种情况下，如何完成OnStart（）方法？在不改变代码结构的情况下，最好的方法是什么？
添加我的代码的更多部分：
这是我的任务调用的方法：
private void DoWork()
{
while (this.Running)
{
this.GenerateReport();
Thread.Sleep(Settings.Default.DefaultSleepDelay);
}
this.log.LogDebug(string.Format(CultureInfo.InvariantCulture, "Worker thread stopping."));
}
和GenerateReport（）方法：如果服务请求取消，我调用Stop（）方法。此方法抛出TaskCancelledException。
public void GenerateReport()
{
if (this.cancellationToken.IsCancellationRequested)
{
this.Stop();
}
var didwork = false;
try
{
didwork = this.reportGenerator.GenerateReport(this.getPermission, this.TaskId);
}
catch (Exception e)
{
this.log.LogError(ReportGenerator.CorrelationIdForPickingReport, string.Format(CultureInfo.InvariantCulture, "System"), string.Format(CultureInfo.InvariantCulture, "Error during report generation."), 0, e);
}
finally
{
if (!didwork)
{
Thread.Sleep(Settings.Default.ReportGenerationInterval);
}
}
}
答案 0 :(得分：2)
如果没有a good, minimal, complete code example来清楚地说明您的问题，则很难准确理解代码的作用。我发现至少有一些奇怪的事情发生了：
WaitAll()将阻止代码检测到一个出现故障的代码，直到所有任务完成为止。所以他们要么在重新启动之前都需要故障，要么在实际停止服务并取消任务之前你不会检测到故障。v != taskException时间是taskException null。所以在我看来，检查它以后是非空的是没有意义的。所以我不确定是否可以知道解决所有这些代码的最佳方法是什么。也就是说，似乎问题很明显：按照设计，您的OnStart()方法需要及时返回，但您当前的实现无法做到这一点。通过使StartManager()方法成为async方法并使用await将控制权返回给调用者，直到发生一些有趣的事情，这个基本问题似乎是可以解决的。这可能看起来像这样：
public async Task StartManager()
{
foreach (var reportGeneratorThread in this.ReportGenerators)
{
reportGeneratorThread.Start();
Thread.Sleep(1000);
}
try
{
await Task.WhenAll(this.Tasks.ToArray());
}
catch (AggregateException e)
{
foreach (var v in e.InnerExceptions)
{
var taskException = v as TaskCanceledException;
if (v != taskException)
{
foreach (var reportGenerator in this.ReportGenerators)
{
if (reportGenerator.Task.IsFaulted)
{
this.logger.LogEvent(this.Id.ToString(), string.Format(CultureInfo.InvariantCulture, "System"), string.Format(CultureInfo.InvariantCulture, "Unhandled exception from Task " + reportGenerator.Task.Id));
ReportGeneratorThread faultedReportGeneratorThread = this.GetThreadById(reportGenerator.Task.Id);
var index = this.ReportGenerators.FindIndex(t => t.Equals(faultedReportGeneratorThread));
this.DisposeFaultedThread(faultedReportGeneratorThread, index);
this.ReportGenerators[index].Start();
this.logger.LogDebug(string.Format(CultureInfo.InvariantCulture, "Faulted Task, and instance of ReportGeneratorThread is recreated and corresponding task is started"));
break;
}
}
}
else if (taskException != null)
{
this.logger.LogEvent(this.Id.ToString(), string.Format(CultureInfo.InvariantCulture, "System"), string.Format(CultureInfo.InvariantCulture, "Task " + taskException.Task.Id + " has thrown a Task Canceled Exception"));
}
}
}
}
然后你可以从OnStart()这样调用它：
protected override void OnStart(string[] args)
{
// Save the returned Task in a local, just as a hack
// to suppress the compiler warning about not awaiting the call.
// Alternatively, store the Task object somewhere and actually
// do something useful with it.
var _ = this.manager.StartManager();
this.log.LogEvent(this.id.ToString(), string.Format(CultureInfo.InvariantCulture, "System"), string.Format(CultureInfo.InvariantCulture, "Service started"));
}
请注意，上面提出的修改无法解决我提到的任何奇怪问题。在我看来，该方法的更有用的实现可能看起来像这样：
public async Task StartManager()
{
foreach (var reportGeneratorThread in this.ReportGenerators)
{
reportGeneratorThread.Start();
}
while (true)
{
try
{
Task task = await Task.WhenAny(this.Tasks.ToArray());
if (task.IsFaulted)
{
// Unpack the exception. Alternatively, you could just retrieve the
// AggregateException directly from task.Exception and process it
// exactly as in the original code (i.e. enumerate the
// AggregateException.InnerExceptions collection). Note that in
// that case, you will see only a single exception in the
// InnerExceptions collection. To detect exceptions in additional
// tasks, you would need to await them as well. Fortunately,
// this will happen each time you loop back and call Task.WhenAny()
// again, since all the tasks are in the Tasks collection being
// passed to WhenAny().
await task;
}
}
catch (Exception v)
{
var taskException = v as TaskCanceledException;
if (v != taskException)
{
foreach (var reportGenerator in this.ReportGenerators)
{
if (reportGenerator.Task.IsFaulted)
{
this.logger.LogEvent(this.Id.ToString(), string.Format(CultureInfo.InvariantCulture, "System"), string.Format(CultureInfo.InvariantCulture, "Unhandled exception from Task " + reportGenerator.Task.Id));
ReportGeneratorThread faultedReportGeneratorThread = this.GetThreadById(reportGenerator.Task.Id);
var index = this.ReportGenerators.FindIndex(t => t.Equals(faultedReportGeneratorThread));
this.DisposeFaultedThread(faultedReportGeneratorThread, index);
this.ReportGenerators[index].Start();
this.logger.LogDebug(string.Format(CultureInfo.InvariantCulture, "Faulted Task, and instance of ReportGeneratorThread is recreated and corresponding task is started"));
break;
}
}
}
else
{
this.logger.LogEvent(this.Id.ToString(), string.Format(CultureInfo.InvariantCulture, "System"), string.Format(CultureInfo.InvariantCulture, "Task " + taskException.Task.Id + " has thrown a Task Canceled Exception"));
// Cancelling tasks...time to exit
return;
}
}
}
}
以上将循环，在发生故障时立即重启故障任务，但如果取消则完全退出。
注意：缺少一个好的代码示例，上面是浏览器代码：完全未编译，未经测试。我不记得从WhenAll()和WhenAny()传播异常的具体细节......我想我的例子是正确的，但你完全有可能需要调整它的具体细节。我希望至少基本思想能以有用的方式表达出来。