Closes #22060: Merge with 3.4

1 files changed, 6 insertions, 21 deletions

diff --git a/Lib/multiprocessing/pool.py b/Lib/multiprocessing/pool.py
index 8832a5ceb2..75a76a4679 100644
--- a/Lib/multiprocessing/pool.py
+++ b/Lib/multiprocessing/pool.py
@@ -87,7 +87,7 @@ class MaybeEncodingError(Exception):
                                                              self.exc)
 
     def __repr__(self):
-        return "<MaybeEncodingError: %s>" % str(self)
+        return "<%s: %s>" % (self.__class__.__name__, self)
 
 
 def worker(inqueue, outqueue, initializer=None, initargs=(), maxtasks=None,
@@ -666,8 +666,7 @@ class IMapIterator(object):
         return self
 
     def next(self, timeout=None):
-        self._cond.acquire()
-        try:
+        with self._cond:
             try:
                 item = self._items.popleft()
             except IndexError:
@@ -680,8 +679,6 @@ class IMapIterator(object):
                     if self._index == self._length:
                         raise StopIteration
                     raise TimeoutError
-        finally:
-            self._cond.release()
 
         success, value = item
         if success:
@@ -691,8 +688,7 @@ class IMapIterator(object):
     __next__ = next                    # XXX
 
     def _set(self, i, obj):
-        self._cond.acquire()
-        try:
+        with self._cond:
             if self._index == i:
                 self._items.append(obj)
                 self._index += 1
@@ -706,18 +702,13 @@ class IMapIterator(object):
 
             if self._index == self._length:
                 del self._cache[self._job]
-        finally:
-            self._cond.release()
 
     def _set_length(self, length):
-        self._cond.acquire()
-        try:
+        with self._cond:
             self._length = length
             if self._index == self._length:
                 self._cond.notify()
                 del self._cache[self._job]
-        finally:
-            self._cond.release()
 
 #
 # Class whose instances are returned by `Pool.imap_unordered()`
@@ -726,15 +717,12 @@ class IMapIterator(object):
 class IMapUnorderedIterator(IMapIterator):
 
     def _set(self, i, obj):
-        self._cond.acquire()
-        try:
+        with self._cond:
             self._items.append(obj)
             self._index += 1
             self._cond.notify()
             if self._index == self._length:
                 del self._cache[self._job]
-        finally:
-            self._cond.release()
 
 #
 #
@@ -760,10 +748,7 @@ class ThreadPool(Pool):
     @staticmethod
     def _help_stuff_finish(inqueue, task_handler, size):
         # put sentinels at head of inqueue to make workers finish
-        inqueue.not_empty.acquire()
-        try:
+        with inqueue.not_empty:
             inqueue.queue.clear()
             inqueue.queue.extend([None] * size)
             inqueue.not_empty.notify_all()
-        finally:
-            inqueue.not_empty.release()