IndexError: pop from empty list

[gusibi]

elasticapm/traces.py

def end_span(self, skip_frames):
        span = self.span_stack.pop()

span_stack may be empty

IndexError: pop from empty list

[beniwohli]

Thanks @gusibi! Usually, when this happens, it is caused by another bug. Do you have the full stack trace of this error?

[gusibi]

[gusibi]

redis server is pika
https://github.com/Qihoo360/pika

[beniwohli]

Thanks for the update. It's hard to say what exactly can cause this. The only place where we call begin_span is in capture_span.__enter__, and the only place where we call end_span is in capture_span.__exit__. According to the context manager protocol, if we __enter__, we will also always __exit__.

So the only explanation that I have is that the transaction object in __enter__ is different than the one in __exit__.

@gusibi do you per chance use an asynchronous framework (asyncio, twisted, ...)? We currently don't support asynchronous execution (see #16), and I could imagine that it could cause an error like this.

[gusibi]

@beniwohli Thanks
I use the flask, not used asynchronous framework.

This error all in the process of using redis.
And not every time this error occurs.