1 files changed, 25 insertions, 1 deletions
diff --git a/Lib/test/_test_multiprocessing.py b/Lib/test/_test_multiprocessing.py
index 11a6310..cfd801e 100644
--- a/Lib/test/_test_multiprocessing.py
+++ b/Lib/test/_test_multiprocessing.py
@@ -26,7 +26,7 @@ import test.support.script_helper
 _multiprocessing = test.support.import_module('_multiprocessing')
 # Skip tests if sem_open implementation is broken.
 test.support.import_module('multiprocessing.synchronize')
-# import threading after _multiprocessing to raise a more revelant error
+# import threading after _multiprocessing to raise a more relevant error
 # message: "No module named _multiprocessing". _multiprocessing is not compiled
 # without thread support.
 import threading
@@ -1668,6 +1668,10 @@ def sqr(x, wait=0.0):
 def mul(x, y):
     return x*y
 
+def raise_large_valuerror(wait):
+    time.sleep(wait)
+    raise ValueError("x" * 1024**2)
+
 class SayWhenError(ValueError): pass
 
 def exception_throwing_generator(total, when):
@@ -1910,6 +1914,26 @@ class _TestPool(BaseTestCase):
             with self.assertRaises(RuntimeError):
                 p.apply(self._test_wrapped_exception)
 
+    def test_map_no_failfast(self):
+        # Issue #23992: the fail-fast behaviour when an exception is raised
+        # during map() would make Pool.join() deadlock, because a worker
+        # process would fill the result queue (after the result handler thread
+        # terminated, hence not draining it anymore).
+
+        t_start = time.time()
+
+        with self.assertRaises(ValueError):
+            with self.Pool(2) as p:
+                try:
+                    p.map(raise_large_valuerror, [0, 1])
+                finally:
+                    time.sleep(0.5)
+                    p.close()
+                    p.join()
+
+        # check that we indeed waited for all jobs
+        self.assertGreater(time.time() - t_start, 0.9)
+
 
 def raising():
     raise KeyError("key")