Handle exception cycles

[hinthornw]

When extracting frames for dict tracebacks, it's possible for exception cause chains to have cycles if a user calls raise e from <something in its chain>. Tracking the seen IDs would let the traceback break early in this case.

Thanks for maintaining a great library!

[hynek]

hey sorry for the late answer – it's been… busy. Is this a fix to the same thing as #727? It looks similar but the approach looks very different?

cc @sscherfke

[sscherfke]

@hinthornw Does the current structlog version fix the issue for you? #727 should have fixed the issue. Otherwise, please provide more details and a minimal example.

[hinthornw]

Thanks for the reply, @sscherfke and @hynek !

No, it is not the same thing as #727
No, main does not fix this.

My minimal example is in the test case I added to this pr.

Or shorter:

try:
   raise ValueError("...")
except Exception as e:
    raise e from e

Creates an infinite recursion in the logging traceback.

I know that code snippet is dumb. I have a server implementation that executes user code. It uses structlog because you all have made a great library. User code can do somewhat dumb things like this code snippet. Structlog's current behavior makes a single error (impacting 1 request) terminal for the server.

[hynek]

I hope #739 has fixed it now on main, since he took over your test (and I've co-authored you).

sorry for the delays, all the timings on this whole story were terrible