Merge fixes for #13854 and #12157.

Lib/multiprocessing/pool.py

@@ -576,6 +576,7 @@ class MapResult(ApplyResult):
         if chunksize <= 0:
             self._number_left = 0
             self._event.set()
+            del cache[self._job]
         else:
             self._number_left = length//chunksize + bool(length % chunksize)
 

Lib/multiprocessing/process.py

@@ -262,11 +262,11 @@ class Process(object):
         except SystemExit as e:
             if not e.args:
                 exitcode = 1
-            elif type(e.args[0]) is int:
+            elif isinstance(e.args[0], int):
                 exitcode = e.args[0]
             else:
-                sys.stderr.write(e.args[0] + '\n')
-                exitcode = 1
+                sys.stderr.write(str(e.args[0]) + '\n')
+                exitcode = 0 if isinstance(e.args[0], str) else 1
         except:
             exitcode = 1
             import traceback

Lib/test/test_multiprocessing.py

@@ -439,6 +439,36 @@ class _TestSubclassingProcess(BaseTestCase):
         1/0 # MARKER
 
 
+    @classmethod
+    def _test_sys_exit(cls, reason, testfn):
+        sys.stderr = open(testfn, 'w')
+        sys.exit(reason)
+
+    def test_sys_exit(self):
+        # See Issue 13854
+        if self.TYPE == 'threads':
+            return
+
+        testfn = test.support.TESTFN
+        self.addCleanup(test.support.unlink, testfn)
+
+        for reason, code in (([1, 2, 3], 1), ('ignore this', 0)):
+            p = self.Process(target=self._test_sys_exit, args=(reason, testfn))
+            p.daemon = True
+            p.start()
+            p.join(5)
+            self.assertEqual(p.exitcode, code)
+
+            with open(testfn, 'r') as f:
+                self.assertEqual(f.read().rstrip(), str(reason))
+
+        for reason in (True, False, 8):
+            p = self.Process(target=sys.exit, args=(reason,))
+            p.daemon = True
+            p.start()
+            p.join(5)
+            self.assertEqual(p.exitcode, reason)
+
 #
 #
 #
@@ -1342,6 +1372,18 @@ class _TestPool(BaseTestCase):
         join()
         self.assertLess(join.elapsed, 0.5)
 
+    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 raising():
     raise KeyError("key")
 
@@ -2487,7 +2529,7 @@ class ProcessesMixin(object):
         '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')
@@ -2501,7 +2543,7 @@ class ManagerMixin(object):
     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')
@@ -2515,7 +2557,7 @@ class ThreadsMixin(object):
         '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')

Misc/NEWS

@@ -21,6 +21,12 @@ Core and Builtins
 Library
 -------
 
+- Issue #13854: Make multiprocessing properly handle non-integer
+  non-string argument to SystemExit.
+
+- Issue #12157: Make pool.map() empty iterables correctly.  Initial
+  patch by mouad.
+
 - Issue #11823: disassembly now shows argument counts on calls with keyword args.
 
 - Issue #14711: os.stat_float_times() has been deprecated.