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-rw-r--r--Lib/test/_test_multiprocessing.py28
1 files changed, 28 insertions, 0 deletions
diff --git a/Lib/test/_test_multiprocessing.py b/Lib/test/_test_multiprocessing.py
index 9b789c2..b053342 100644
--- a/Lib/test/_test_multiprocessing.py
+++ b/Lib/test/_test_multiprocessing.py
@@ -18,6 +18,7 @@ import random
import logging
import struct
import operator
+import weakref
import test.support
import test.support.script_helper
@@ -1668,6 +1669,19 @@ def sqr(x, wait=0.0):
def mul(x, y):
return x*y
+def identity(x):
+ return x
+
+class CountedObject(object):
+ n_instances = 0
+
+ def __new__(cls):
+ cls.n_instances += 1
+ return object.__new__(cls)
+
+ def __del__(self):
+ type(self).n_instances -= 1
+
class SayWhenError(ValueError): pass
def exception_throwing_generator(total, when):
@@ -1676,6 +1690,7 @@ def exception_throwing_generator(total, when):
raise SayWhenError("Somebody said when")
yield i
+
class _TestPool(BaseTestCase):
@classmethod
@@ -1910,6 +1925,19 @@ class _TestPool(BaseTestCase):
with self.assertRaises(RuntimeError):
p.apply(self._test_wrapped_exception)
+ def test_release_task_refs(self):
+ # Issue #29861: task arguments and results should not be kept
+ # alive after we are done with them.
+ objs = [CountedObject() for i in range(10)]
+ refs = [weakref.ref(o) for o in objs]
+ self.pool.map(identity, objs)
+
+ del objs
+ self.assertEqual(set(wr() for wr in refs), {None})
+ # With a process pool, copies of the objects are returned, check
+ # they were released too.
+ self.assertEqual(CountedObject.n_instances, 0)
+
def raising():
raise KeyError("key")