Handle exception thrown by ProcessName during ProcessEx timeout

[halter73]

Unhandled exception. System.AggregateException: One or more errors occurred. (Process has exited, so the requested information is not available.)
 ---> System.InvalidOperationException: Process has exited, so the requested information is not available.
   at System.Diagnostics.Process.EnsureState(State state)
   at System.Diagnostics.Process.get_ProcessName()
   at Microsoft.AspNetCore.Internal.ProcessEx.<>c__DisplayClass13_0.<.ctor>b__0() in /_/src/Shared/Process/ProcessEx.cs:line 55
   at System.Threading.CancellationToken.<>c.<.cctor>b__26_0(Object obj)
   at System.Threading.CancellationTokenSource.CallbackNode.<>c.<ExecuteCallback>b__9_0(Object s)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
--- End of stack trace from previous location ---
   at System.Threading.CancellationTokenSource.CallbackNode.ExecuteCallback()
   at System.Threading.CancellationTokenSource.ExecuteCallbackHandlers(Boolean throwOnFirstException)
   --- End of inner exception stack trace ---
   at System.Threading.CancellationTokenSource.ExecuteCallbackHandlers(Boolean throwOnFirstException)
   at System.Threading.TimerQueueTimer.CallCallback(Boolean isThreadPool)
   at System.Threading.TimerQueueTimer.Fire(Boolean isThreadPool)
   at System.Threading.TimerQueue.FireNextTimers()

Process.ProcessName throwing in your CT callback caused BlazorTemplates.Tests to hang on our CI server.

https://dev.azure.com/dnceng/public/_build/results?buildId=731663&view=results

[ghost]

Hello @ajaybhargavb!

Because this pull request has the auto-merge label, I will be glad to assist with helping to merge this pull request once all check-in policies pass.

p.s. you can customize the way I help with merging this pull request, such as holding this pull request until a specific person approves. Simply @mention me (@msftbot) and give me an instruction to get started! Learn more here.

[dougbu]

Late questions (sorry):

1. Have you confirmed ProcessName is available here i.e. the process is always started before the constructor is called❔
2. Do we need a similar change in src/Tools/Microsoft.dotnet-openapi/test/ProcessEx.cs and wherever else we have similar Process wrappers❔ (No, I don't remember why we have more than one ProcessEx class.)

[halter73]

1. _process is private and there's no mechanism in ProcessEx to start a process, so it must be started here.
2. That's probably a good idea. I didn't know there were copies of this. Is that the only other one?