gh-125864: Propagate pickle.loads() failures in InterpreterPoolExecutor (gh-125898)

Authored-by: Peter Bierma <[email protected]>

Author: ZeroIntensity

Lib/concurrent/futures/interpreter.py

@@ -107,7 +107,8 @@ def _call(cls, func, args, kwargs, resultsid):
 
     @classmethod
     def _call_pickled(cls, pickled, resultsid):
-        fn, args, kwargs = pickle.loads(pickled)
+        with cls._capture_exc(resultsid):
+            fn, args, kwargs = pickle.loads(pickled)
         cls._call(fn, args, kwargs, resultsid)
 
     def __init__(self, initdata, shared=None):

Lib/test/test_concurrent_futures/test_interpreter_pool.py

@@ -56,6 +56,16 @@ def pipe(self):
         return r, w
 
 
+class PickleShenanigans:
+    """Succeeds with pickle.dumps(), but fails with pickle.loads()"""
+    def __init__(self, value):
+        if value == 1:
+            raise RuntimeError("gotcha")
+
+    def __reduce__(self):
+        return (self.__class__, (1,))
+
+
 class InterpreterPoolExecutorTest(
             InterpretersMixin, ExecutorTest, BaseTestCase):
 
@@ -279,6 +289,14 @@ def test_idle_thread_reuse(self):
         self.assertEqual(len(executor._threads), 1)
         executor.shutdown(wait=True)
 
+    def test_pickle_errors_propagate(self):
+        # GH-125864: Pickle errors happen before the script tries to execute, so the
+        # queue used to wait infinitely.
+
+        fut = self.executor.submit(PickleShenanigans(0))
+        with self.assertRaisesRegex(RuntimeError, "gotcha"):
+            fut.result()
+
 
 class AsyncioTest(InterpretersMixin, testasyncio_utils.TestCase):