Issue #12157: pool.map() does not handle empty iterable correctly
Initial patch by mouad
diff --git a/Lib/test/test_multiprocessing.py b/Lib/test/test_multiprocessing.py
index 0fe6497..42b2d91 100644
--- a/Lib/test/test_multiprocessing.py
+++ b/Lib/test/test_multiprocessing.py
@@ -1152,6 +1152,18 @@
join()
self.assertTrue(join.elapsed < 0.2)
+ def test_empty_iterable(self):
+ # See Issue 12157
+ p = self.Pool(1)
+
+ self.assertEqual(p.map(sqr, []), [])
+ self.assertEqual(list(p.imap(sqr, [])), [])
+ self.assertEqual(list(p.imap_unordered(sqr, [])), [])
+ self.assertEqual(p.map_async(sqr, []).get(), [])
+
+ p.close()
+ p.join()
+
def unpickleable_result():
return lambda: 42
@@ -2113,7 +2125,7 @@
'Queue', 'Lock', 'RLock', 'Semaphore', 'BoundedSemaphore',
'Condition', 'Event', 'Value', 'Array', 'RawValue',
'RawArray', 'current_process', 'active_children', 'Pipe',
- 'connection', 'JoinableQueue'
+ 'connection', 'JoinableQueue', 'Pool'
)))
testcases_processes = create_test_cases(ProcessesMixin, type='processes')
@@ -2127,7 +2139,7 @@
locals().update(get_attributes(manager, (
'Queue', 'Lock', 'RLock', 'Semaphore', 'BoundedSemaphore',
'Condition', 'Event', 'Value', 'Array', 'list', 'dict',
- 'Namespace', 'JoinableQueue'
+ 'Namespace', 'JoinableQueue', 'Pool'
)))
testcases_manager = create_test_cases(ManagerMixin, type='manager')
@@ -2141,7 +2153,7 @@
'Queue', 'Lock', 'RLock', 'Semaphore', 'BoundedSemaphore',
'Condition', 'Event', 'Value', 'Array', 'current_process',
'active_children', 'Pipe', 'connection', 'dict', 'list',
- 'Namespace', 'JoinableQueue'
+ 'Namespace', 'JoinableQueue', 'Pool'
)))
testcases_threads = create_test_cases(ThreadsMixin, type='threads')