[3.11] gh-92530: Fix an issue that occurred after interrupting threading.Condition...

If Condition.notify() was interrupted just after it released the waiter lock,
but before removing it from the queue, the following calls of notify() failed
with RuntimeError: cannot release un-acquired lock.
(cherry picked from commit 70af994fee7c0850ae859727d9468a5f29375a38)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
Automerge-Triggered-By: GH:serhiy-storchaka

diff --git a/Lib/threading.py b/Lib/threading.py
index 642f93e1eec31ce4d66b6176e78593d7bf7cb232..8e7cdf6f620d8fd998a81ddef1bd3e6eb5a145ce 100644 (file)
--- a/Lib/threading.py
+++ b/Lib/threading.py
@@ -368,14 +368,21 @@ class Condition:
         """
         if not self._is_owned():
             raise RuntimeError("cannot notify on un-acquired lock")
-        all_waiters = self._waiters
-        waiters_to_notify = _deque(_islice(all_waiters, n))
-        if not waiters_to_notify:
-            return
-        for waiter in waiters_to_notify:
-            waiter.release()
+        waiters = self._waiters
+        while waiters and n > 0:
+            waiter = waiters[0]
+            try:
+                waiter.release()
+            except RuntimeError:
+                # gh-92530: The previous call of notify() released the lock,
+                # but was interrupted before removing it from the queue.
+                # It can happen if a signal handler raises an exception,
+                # like CTRL+C which raises KeyboardInterrupt.
+                pass
+            else:
+                n -= 1
             try:
-                all_waiters.remove(waiter)
+                waiters.remove(waiter)
             except ValueError:
                 pass
 

diff --git a/Misc/NEWS.d/next/Library/2022-05-09-09-28-02.gh-issue-92530.M4Q1RS.rst b/Misc/NEWS.d/next/Library/2022-05-09-09-28-02.gh-issue-92530.M4Q1RS.rst
new file mode 100644 (file)
index 0000000..8bb8ca0
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2022-05-09-09-28-02.gh-issue-92530.M4Q1RS.rst
@@ -0,0 +1,2 @@
+Fix an issue that occurred after interrupting
+:func:`threading.Condition.notify`.