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diagnostic: document waithandle keyword #40852

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f131b03
dotnet-trace: document waithandle keyword
verdie-g May 11, 2024
14544d7
Document events
verdie-g May 28, 2024
30cd953
Fix ClrInstanceID type
verdie-g May 28, 2024
b760c1d
Update docs/fundamentals/diagnostics/runtime-events.md
BillWagner Oct 16, 2024
ef43d93
Apply suggestions from code review
BillWagner Oct 16, 2024
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1 change: 1 addition & 0 deletions docs/core/diagnostics/dotnet-trace.md
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Expand Up @@ -153,6 +153,7 @@ dotnet-trace collect [--buffersize <size>] [--clreventlevel <clreventlevel>] [--
| `compilationdiagnostic` | `0x2000000000` |
| `methoddiagnostic` | `0x4000000000` |
| `typediagnostic` | `0x8000000000` |
| `waithandle` | `0x40000000000` |

You can read about the CLR provider more in detail on the [.NET runtime provider reference documentation](../../fundamentals/diagnostics/runtime-events.md).

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3 changes: 3 additions & 0 deletions docs/fundamentals/diagnostics/runtime-events.md
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Expand Up @@ -43,3 +43,6 @@ These events collect information about the type system.

[Tiered compilation events](runtime-tiered-compilation-events.md)\
These events collect information about tiered compilation.

[Wait handle events](runtime-wait-handle-events.md)\
These events collect information about wait handles. They help to diagnostic thread pool starvations.
55 changes: 55 additions & 0 deletions docs/fundamentals/diagnostics/runtime-wait-handle-events.md
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@@ -0,0 +1,55 @@
---
title: "Wait handle runtime events"
description: See ETW events that collect information specific to the wait handles.
ms.date: "05/27/2024"
helpviewer_keywords:
- "wait handle events (CoreCLR)"
- "ETW, EventPipe, LTTng wait handle events (CoreCLR)"
---

# .NET runtime wait handle events

These runtime events capture information about wait handles. They can be useful to investigate thread pool starvation issues. For more information about how to use these events for diagnostic purposes, see [logging and tracing .NET applications](../../core/diagnostics/logging-tracing.md)

## WaitHandleWaitStart event

This event is emitted at the start of a wait operation on a wait handle. Here is a non-exhaustive list of managed method that could emit this event:

- `Monitor.Wait`
- `Monitor.Enter` or the C# lock keyword
- `ManualResetEvent.WaitOne`
- `Task.Wait`

|Keyword for raising the event|Level|
|-----------------------------------|-----------|
|`WaitHandleKeyword` (0x40000000000)|Verbose (5)|

The following table shows event information.

|Event|Event ID|Raised when|
|-----------|--------------|-----------------|
|`WaitHandleWaitStart`|301|A wait starts.|

|Field name|Data type|Description|
|----------------|---------------|-----------------|
|`WaitSource`|`win:UInt8`|`0x0` - Other sources.<br /><br /> `0x1` - The wait originated from managed code through the `Monitor.Wait` method.|
|`AssociatedObjectID`|`win:Pointer`|Address of the associated object (e.g. address of `obj` in the code `lock(obj) {}`).|
|`ClrInstanceID`|`win:UInt16`|Unique ID for the instance of CoreCLR.|

## WaitHandleWaitStop event

This event is emitted at the end of a wait operation on a wait handle.

|Keyword for raising the event|Level|
|-----------------------------------|-----------|
|`WaitHandleKeyword` (0x40000000000)|Verbose (5)|

The following table shows event information.

|Event|Event ID|Raised when|
|-----------|--------------|-----------------|
|`WaitHandleWaitStop`|302|A wait stops.|

|Field name|Data type|Description|
|----------------|---------------|-----------------|
|`ClrInstanceID`|`win:UInt16`|Unique ID for the instance of CoreCLR.|
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