gh-141617: clarify concurrent.futures.ThreadPoolExecutor deadlock example (#141620)

Yashp002 · picnixz · web-flow · commit 171133aa84cd · 2026-03-09T16:30:00.000Z
---------

Co-authored-by: Bénédikt Tran &lt;10796600+picnixz@users.noreply.github.com&gt;
diff --git a/Doc/library/concurrent.futures.rst b/Doc/library/concurrent.futures.rst
@@ -156,7 +156,9 @@ And::
        print(f.result())
 
    executor = ThreadPoolExecutor(max_workers=1)
-   executor.submit(wait_on_future)
+   future = executor.submit(wait_on_future)
+   # Note: calling future.result() would also cause a deadlock because
+   # the single worker thread is already waiting for wait_on_future().
 
 
 .. class:: ThreadPoolExecutor(max_workers=None, thread_name_prefix='', initializer=None, initargs=())
