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gh-141617: Add missing result() call in concurrent.futures example #141620

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gh-141617: Add missing result() call in concurrent.futures example
Yashp002 Nov 16, 2025
6dd6b65
gh-141617: Clarify ThreadPoolExecutor deadlock example in docs
Yashp002 Nov 17, 2025
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10 changes: 7 additions & 3 deletions Doc/library/concurrent.futures.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -40,7 +40,9 @@ Executor Objects
with ThreadPoolExecutor(max_workers=1) as executor:
future = executor.submit(pow, 323, 1235)
print(future.result())

# Note: calling future.result() outside this with statement would work fine,
# but calling it here is safe because we print it immediately and the executor
# can complete the task before the context manager exits.
.. method:: map(fn, *iterables, timeout=None, chunksize=1, buffersize=None)

Similar to :func:`map(fn, *iterables) <map>` except:
Expand Down Expand Up @@ -151,8 +153,10 @@ And::
print(f.result())

executor = ThreadPoolExecutor(max_workers=1)
executor.submit(wait_on_future)

executor.submit(wait_on_future).result()
# Note: calling future.result() here would cause a deadlock because the single
# worker thread is already executing wait_on_future(), which itself is waiting
# for a result from the same executor.

.. class:: ThreadPoolExecutor(max_workers=None, thread_name_prefix='', initializer=None, initargs=())

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