HttpConnectionContext.TickHeartbeat() in SignalR ticks after the context is disposed, causing runtime errors when accessing context from heartbeat handlers

[Amy-B-Tradition]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

HubCallerContext is already disposed, its getter throws an error instead of doing anything useful (like returning a context where someone could check if it's disposed before trying to use it). When users attach OnHeartbeat handlers, I think it's fair to expect that the framework will stop calling them once the session is disposed. However, it seems like sometimes the heartbeats continue after this point, and this generates runtime errors because who wraps their property access attempts in a try/catch.

Expected Behavior

Heartbeat handlers are no longer called after session dispose, or accessor does not throw an error and Context has a property that devs can check themselves.

Steps To Reproduce

No response

Exceptions (if any)

No response

.NET Version

No response

Anything else?

No response

[BrennanConroy]

Could you provide a specific example? The disposed check you show above is on the Hub type and happens after every single Hub method call. You shouldn't be accessing the Hub after the Hub method is completed.

[Amy-B-Tradition]

Looking at your own code should indicate to you it's programmed in such a way it will fail. I'm actually a front-end programmer most of the time, so I'm not going to submit a repro case. We've worked around it some other way already.

Please note that the call the code was making was only nominally a method call. It was to a getter. The Hub didn't know it was disconnected, obviously, at the place this was called, in the heartbeat handlers.

Also, what's up with ignoring the issue for several months, then expecting me to jump right on it or you'll close it?

[BrennanConroy]

Sorry, we got behind on triaging issues and are trying to catch up.

Given the issue had no other community interaction and looking through the code and your provided information seems to indicate an app bug not a framework bug, the issue was marked as needing more information. I'll reopen for now, but as I'll try to explain below, I don't think there is anything for SignalR to change.

It was to a getter. The Hub didn't know it was disconnected, obviously, at the place this was called, in the heartbeat handlers.

The getter on the Hub throws if the Hub is disposed. The Hub is disposed immediately after a Hub method finishes running. This means your app must have a background task running which is accessing the Hub after the Hub method completes. This is not supported. If you want to use the HubCallerContext in a background task that's fine, but you should grab it before starting your background task, or make sure the Hub method is still running when you call the getter.