gh-107219: Fix concurrent.futures terminate_broken() (#108974)

Fix a race condition in _ExecutorManagerThread.terminate_broken():
ignore the InvalidStateError on future.set_exception(). It can happen
if the future is cancelled before the caller.

Moreover, test_crash_big_data() now waits explicitly until the
executor completes.

1 files changed, 8 insertions, 1 deletions

diff --git a/Lib/concurrent/futures/process.py b/Lib/concurrent/futures/process.py
index 301207f..9933d3d 100644
--- a/Lib/concurrent/futures/process.py
+++ b/Lib/concurrent/futures/process.py
@@ -489,7 +489,14 @@ class _ExecutorManagerThread(threading.Thread):
 
         # Mark pending tasks as failed.
         for work_id, work_item in self.pending_work_items.items():
-            work_item.future.set_exception(bpe)
+            try:
+                work_item.future.set_exception(bpe)
+            except _base.InvalidStateError as exc:
+                # set_exception() fails if the future is cancelled: ignore it.
+                # Trying to check if the future is cancelled before calling
+                # set_exception() would leave a race condition if the future is
+                # cancelled betwen the check and set_exception().
+                pass
             # Delete references to object. See issue16284
             del work_item
         self.pending_work_items.clear()