Common crash related to websocket failing with error

[SpencerCDixon]

Which version of the Ably SDK are you using?

1d0d4df4ff4fd816a1e92d3c3b8407b76e5e9114

On which platform does the issue happen?

macOS

Are you using Carthage?

Are you using Cocoapods?

We've added the dep as a submodule

Which version of Xcode are you using?

Xcode 12.2
Build version 12B5025f

What did you do?

Have a regular crash related to the library and was wondering if other folks also experienced it.

What happened instead?

Here is a stack trace of where the crash is occurring.

Crashed: io.ably.main
0  libdispatch.dylib              0x7fff7299517c _dispatch_continuation_init_slow + 64
1  libdispatch.dylib              0x7fff729a46b0 dispatch_after + 521
2  Ably                           0x10ea88712 artDispatchScheduled + 324
3  Ably                           0x10ea9196a -[ARTEventListener startTimer] + 131
4  Ably                           0x10eab79ee -[ARTRealtimeInternal transition:withErrorInfo:] + 481
5  Ably                           0x10eab7a71 -[ARTRealtimeInternal transitionToDisconnectedOrSuspendedWithError:] + 76
6  Ably                           0x10eabeaa0 -[ARTRealtimeInternal realtimeTransportFailed:withError:] + 807
7  Ably                           0x10ea8f044 -[ARTWebSocketTransport webSocket:didFailWithError:] + 180
8  libdispatch.dylib              0x7fff72990d53 _dispatch_call_block_and_release + 12
9  libdispatch.dylib              0x7fff72991dcf _dispatch_client_callout + 8
10 libdispatch.dylib              0x7fff72998124 _dispatch_lane_serial_drain + 618
11 libdispatch.dylib              0x7fff72998bdc _dispatch_lane_invoke + 388
12 libdispatch.dylib              0x7fff729a1090 _dispatch_workloop_worker_thread + 603
13 libsystem_pthread.dylib        0x7fff72bd260b _pthread_wqthread + 409
14 libsystem_pthread.dylib        0x7fff72bd2405 start_wqthread + 13

Has anything like this been reported before? Is there any other info I could try and get which would be useful in debugging?

┆Issue is synchronized with this Jira Bug by Unito

[QuintinWillison]

Thanks for the report, @SpencerCDixon 😁

I'm not aware of anybody else reporting this yet but I see you are using the latest release so it's clearly a concern!
When you say it's a "regular crash", can you expand on that a little? Any idea of a way to reproduce?

Also, is this blocking you right now?
@ricardopereira should be able to take a look later in the week, if that's soon enough.

[SpencerCDixon]

When you say it's a "regular crash", can you expand on that a little? Any idea of a way to reproduce?

It's our most common crash which is why we're now tracking it down. Probably get it ~20-30 times a week. We haven't gotten many user reports so I imagine it's happening primarily in the background when computers sleep and wake up.

No reliable way to reproduce unfortunately :(

Appears to me like a null pointer deref, but I could be totally off!

Seems to happen on MBP more than other devices (but we probably also just have way more users using MBPs so hard to say for sure).

Also, is this blocking you right now?

Not a huge blocker but would be nice to get it resolved soonish. Happy to try any git SHAs in future releases to see if it resolves the issue.

[QuintinWillison]

That info does help direct our investigations. I'll discuss with the team. Thanks, @SpencerCDixon. 😁