Issue #6963: Added maxtasksperchild argument to multiprocessing.Pool

1 files changed, 25 insertions, 1 deletions

diff --git a/Lib/test/test_multiprocessing.py b/Lib/test/test_multiprocessing.py
index ae3b721..1f80c78 100644
--- a/Lib/test/test_multiprocessing.py
+++ b/Lib/test/test_multiprocessing.py
@@ -45,7 +45,7 @@ latin = str
 #
 
 LOG_LEVEL = util.SUBWARNING
-#LOG_LEVEL = logging.WARNING
+#LOG_LEVEL = logging.DEBUG
 
 DELTA = 0.1
 CHECK_TIMINGS = False     # making true makes tests take a lot longer
@@ -1052,6 +1052,30 @@ class _TestPool(BaseTestCase):
         join = TimingWrapper(self.pool.join)
         join()
         self.assertTrue(join.elapsed < 0.2)
+
+class _TestPoolWorkerLifetime(BaseTestCase):
+
+    ALLOWED_TYPES = ('processes', )
+    def test_pool_worker_lifetime(self):
+        p = multiprocessing.Pool(3, maxtasksperchild=10)
+        self.assertEqual(3, len(p._pool))
+        origworkerpids = [w.pid for w in p._pool]
+        # Run many tasks so each worker gets replaced (hopefully)
+        results = []
+        for i in range(100):
+            results.append(p.apply_async(sqr, (i, )))
+        # Fetch the results and verify we got the right answers,
+        # also ensuring all the tasks have completed.
+        for (j, res) in enumerate(results):
+            self.assertEqual(res.get(), sqr(j))
+        # Refill the pool
+        p._repopulate_pool()
+        # Finally, check that the worker pids have changed
+        finalworkerpids = [w.pid for w in p._pool]
+        self.assertNotEqual(sorted(origworkerpids), sorted(finalworkerpids))
+        p.close()
+        p.join()
+
 #
 # Test that manager has expected number of shared objects left
 #