Internal exception surfacing when calling `Post` on disposed `MailBoxProcessor`

```
Message: 
System.ObjectDisposedException : Cannot access a disposed object.
Object name: 'Microsoft.Win32.SafeHandles.SafeWaitHandle'.

  Stack Trace: 
SafeHandle.DangerousAddRef(Boolean& success)
Kernel32.SetEvent(SafeWaitHandle handle)
EventWaitHandle.Set()
Mailbox`1.Post(TMsg msg) line 193
FSharpMailboxProcessor`1.Post(TMsg message) line 419
```

I can see the above exception occasionally in this test:
https://github.com/dotnet/fsharp/blob/e6854f5f8d81499742208bdf809bab50944d1d59/tests/FSharp.Core.UnitTests/FSharp.Core/Microsoft.FSharp.Control/MailboxProcessorType.fs#L316

I assume the expected behavior here is no exception?

I'll try to come up with consistent minimal repro, but the problem seems to be here:
https://github.com/dotnet/fsharp/blob/69fa88b1f7577e6efc5598854cc447887ed5b2e4/src/FSharp.Core/mailbox.fs#L189-L193
`ev` is disposed and `Set` will fail.


The fix seems to be to also assign null to `pulse` when disposing it here:
https://github.com/dotnet/fsharp/blob/69fa88b1f7577e6efc5598854cc447887ed5b2e4/src/FSharp.Core/mailbox.fs#L336-L346





	match pulse with
	\| null -> () // no one waiting, leaving the message in the queue is sufficient
	\| ev ->
	// someone is waiting on the wait handle
	ev.Set() \|> ignore

	interface System.IDisposable with
	member _.Dispose() =
	lock syncRoot (fun () ->
	if isNotNull inboxStore then
	inboxStore.Clear()

	arrivals.Clear()
	isDisposed <- true)

	if isNotNull pulse then
	(pulse :> IDisposable).Dispose()

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Internal exception surfacing when calling `Post` on disposed `MailBoxProcessor` #17849

majocha
openedon Oct 8, 2024

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

Internal exception surfacing when calling Post on disposed MailBoxProcessor #17849

Description

majochaopenedon Oct 8, 2024

Metadata