bpo-29861: release references to multiprocessing Pool tasks (#743) (#803)
* bpo-29861: release references to multiprocessing Pool tasks (#743)
* bpo-29861: release references to multiprocessing Pool tasks
Release references to tasks, their arguments and their results as soon
as they are finished, instead of keeping them alive until another task
arrives.
* Comments in test
(cherry picked from commit 8988945cdc27ffa86ba8c624e095b51c459f5154)
* Fix Misc/NEWS ?
diff --git a/Lib/multiprocessing/pool.py b/Lib/multiprocessing/pool.py
index ceb93aa..a47cd0f 100644
--- a/Lib/multiprocessing/pool.py
+++ b/Lib/multiprocessing/pool.py
@@ -120,6 +120,8 @@
debug("Possible encoding error while sending result: %s" % (
wrapped))
put((job, i, (False, wrapped)))
+
+ task = job = result = func = args = kwds = None
completed += 1
debug('worker exiting after %d tasks' % completed)
@@ -362,10 +364,11 @@
if set_length:
debug('doing set_length()')
set_length(i+1)
+ finally:
+ task = taskseq = job = None
else:
debug('task handler got sentinel')
-
try:
# tell result handler to finish when cache is empty
debug('task handler sending sentinel to result handler')
@@ -405,6 +408,7 @@
cache[job]._set(i, obj)
except KeyError:
pass
+ task = job = obj = None
while cache and thread._state != TERMINATE:
try:
@@ -421,6 +425,7 @@
cache[job]._set(i, obj)
except KeyError:
pass
+ task = job = obj = None
if hasattr(outqueue, '_reader'):
debug('ensuring that outqueue is not full')