Merge "Add support for fair locks"3.29.0

1 files changed, 15 insertions, 0 deletions

diff --git a/releasenotes/notes/add-option-for-fair-locks-b6d660e97683cec6.yaml b/releasenotes/notes/add-option-for-fair-locks-b6d660e97683cec6.yaml
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+---
+prelude: >
+    This release includes optional support for fair locks.  When fair locks
+    are specified, blocking waiters will acquire the lock in the order that
+    they blocked.
+features:
+  - |
+    We now have optional support for ``fair`` locks.  When fair locks are
+    specified, blocking waiters will acquire the lock in the order that they
+    blocked.  This can be useful to ensure that existing blocked waiters do
+    not wait indefinitely in the face of large numbers of new attempts to
+    acquire the lock.  When specifying locks as both ``external`` and ``fair``,
+    the ordering *within* a given process will be fair, but the ordering
+    *between* processes will be determined by the behaviour of the underlying
+    OS.