Can ray.util.queue.Empty extend queue.Empty?

[rsamf]

Description

I am trying to catch Empty queue exceptions where my queue can either be a multiprocess queue or ray.util.queue. Currently, I have to do this:

...
except queue.Empty:
    pass
except ray.util.queue.Empty:
    pass

because ray.util.queue.Empty is not a subclass of Python's built-in queue.Empty but rather Python's built-in Exception class. See:

ray/python/ray/util/queue.py

Line 10 in 3c47c39

class Empty(Exception):

A quick fix would be to just change it to extend queue.Empty, and while at it, also change Full to extend queue.Full too?

I think this would be a good first issue. Thanks!

Use case

Code conciseness for Ray users

[wingkitlee0]

Python allows you to catch multiple exceptions like

    ...
except (queue.Empty, ray.util.queue.Empty) as e:
    ...

See https://docs.python.org/3/tutorial/errors.html#handling-exceptions
Does it help?

Also, Ray's Queue is not a subclass of Python's Queue.. so it may cause confusion with the suggestion above

[rsamf]

@wingkitlee0 Right, I'm aware, but I run into the same problem.

Also, Ray's Queue is not a subclass of Python's Queue.. so it may cause confusion with the suggestion above

Python has an implementation of a simple queue: queue.SimpleQueue which doesn't implement queue.Queue but raises queue.Empty, queue.Full, and queue.ShutDown. These are exceptions that aren't for queue.Queue classes but shareable for any queue in Python in my opinion.

[wingkitlee0]

the same problem.

do you mind elaborate?

SimpleQueue ... raises queue.Empty, queue.Full

that's fair. Indeed, multiprocessing.Queue also raises them directly. So maybe Ray should raise them directly as well (without subclass).

[rsamf]

except (queue.Empty, ray.util.queue.Empty):
  ...

Is syntactic sugar for

except queue.Empty:
    ...
except ray.util.queue.Empty:
    ...

I would prefer to do

except queue.Empty:
  ...

in my case.

Raising queue.Empty and queue.Full directly would be even better.