bpo-5001: More-informative multiprocessing error messages (#3079)

* Make error message more informative

Replace assertions in error-reporting code with more-informative version that doesn't cause confusion over where and what the error is.

* Additional clarification + get travis to check

* Change from SystemError to TypeError

As suggested in PR comment by @pitrou, changing from SystemError; TypeError appears appropriate.

* NEWS file installation; ACKS addition (will do my best to justify it by additional work)

* Making current AssertionErrors in multiprocessing more informative

* Blurb added re multiprocessing managers.py, queues.py cleanup

* Further multiprocessing cleanup - went through pool.py

* Fix two asserts in multiprocessing/util.py

* Most asserts in multiprocessing more informative

* Didn't save right version

* Further work on multiprocessing error messages

* Correct typo

* Correct typo v2

* Blasted colon... serves me right for trying to work on two things at once

* Simplify NEWS entry

* Update 2017-08-18-17-16-38.bpo-5001.gwnthq.rst

* Update 2017-08-18-17-16-38.bpo-5001.gwnthq.rst

OK, never mind.

* Corrected (thanks to pitrou) error messages for notify

* Remove extraneous backslash in docstring.

1 files changed, 3 insertions, 3 deletions

diff --git a/Lib/multiprocessing/queues.py b/Lib/multiprocessing/queues.py
index 513807c..328efbd 100644
--- a/Lib/multiprocessing/queues.py
+++ b/Lib/multiprocessing/queues.py
@@ -78,7 +78,7 @@ class Queue(object):
         self._poll = self._reader.poll
 
     def put(self, obj, block=True, timeout=None):
-        assert not self._closed
+        assert not self._closed, "Queue {0!r} has been closed".format(self)
         if not self._sem.acquire(block, timeout):
             raise Full
 
@@ -140,7 +140,7 @@ class Queue(object):
 
     def join_thread(self):
         debug('Queue.join_thread()')
-        assert self._closed
+        assert self._closed, "Queue {0!r} not closed".format(self)
         if self._jointhread:
             self._jointhread()
 
@@ -281,7 +281,7 @@ class JoinableQueue(Queue):
         self._cond, self._unfinished_tasks = state[-2:]
 
     def put(self, obj, block=True, timeout=None):
-        assert not self._closed
+        assert not self._closed, "Queue {0!r} is closed".format(self)
         if not self._sem.acquire(block, timeout):
             raise Full