microsoft/perfview

Freeze processing in EventPipeEventSource if uncaught exception is thrown in callback.

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#1,290 opened on Oct 15, 2020

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bughelp wanted

Description

Environment

  • Microsoft.Diagnostics.Tracing.TraceEvent: 2.0.61
  • Microsoft.Diagnostics.NETCore.Client: 0.2.141901
  • EventPipe sender app and receiver app's TFM: net5.0-rc2

Steps to reproduce

  1. run app which produce EventSource event periodically
  2. start EventPipe session by DiagnosticClient
  3. create EventPipeEventSource from event stream
  4. set callback to DynamicEventParser.All
    • Exception will be thrown in callback
  5. start processing

full test code is uploaded to gist

Expected result

callback is invoked periodicaly, or at least terminate event processing when EventPipeEventSource.StopProcessing is called.

Actual result

callback was never invoked again, and EventPipeEventSource.Process never returned, even if EventPipeEventSource.StopProcessing was called.

Contributor guide

Tech stack
csharp
Domain
observabilityperformance
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
needs investigation
Prerequisites
C#.NETEventPipe
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
20
Research direction
Investigate the EventPipeEventSource class in the Microsoft.Diagnostics.Tracing.TraceEvent library to understand how callbacks are invoked and how exceptions are handled. The issue shows that an uncaught exception in the callback causes the event loop to freeze. Look for try catch blocks around callback invocations and ensure exceptions are caught to avoid freezing. Also check the StopProcessing mechanism to ensure it can interrupt a frozen loop.