When calling Process' join([timeout]) method, the timeout expiration case is indistinguishable from the successful join.  I suppose the 'exitcode' attribute can deliver the necessary information, but perhaps join could stand on its own.

If join() shouldn't be changed, could we make explicit reference to the exitcode attribute in the documentation?

My guess is "it shouldn't", and "yes", but I've added the multiprocessing maintainers as nosy and they can answer definitively.

While it makes sense for `join` to raise an error on timeout, that could possibly break existing code, so I don't think that is an option.  Adding a note in the documentation would be great.

Thread.join() also returns None in all cases so +1 for documenting the current behavior.

I've submitted a documentation patch with #28094.

This patch is intended to document the behaviour of join(). (Originally submitted to #28094)

Tom's patch looks good to me. Davin, can you have a look at it?

New changeset 112060f8abe8 by Berker Peksag in branch '3.5':
Issue #10673: Document that Process.exitcode can be used to determine timeout
https://hg.python.org/cpython/rev/112060f8abe8

New changeset 0414ce8a3b5c by Berker Peksag in branch '3.6':
Issue #10673: Merge from 3.5
https://hg.python.org/cpython/rev/0414ce8a3b5c

New changeset f91650739061 by Berker Peksag in branch 'default':
Issue #10673: Merge from 3.6
https://hg.python.org/cpython/rev/f91650739061

Thanks, Tom.