[Doc] Revamp ray core design patterns doc [15/n]: actor sync

doc/source/ray-core/actors/patterns/index.rst

@@ -14,7 +14,6 @@ You may also be interested in visiting the design patterns section for :ref:`tas
     :maxdepth: -1
 
     tree-of-actors
-    actor-sync
     concurrent-operations-async-actor
     overlapping-computation-communication
     fault-tolerance-actor-checkpointing

doc/source/ray-core/patterns/actor-sync.rst

@@ -0,0 +1,16 @@
+Pattern: Using an actor to synchronize other tasks and actors
+=============================================================
+
+When you have multiple tasks that need to wait on some condition or otherwise
+need to synchronize across tasks & actors on a cluster, you can use a central
+actor to coordinate among them.
+
+Example use case
+----------------
+
+You can use an actor to implement a distributed ``asyncio.Event`` that multiple tasks can wait on.
+
+Code example
+------------
+
+.. literalinclude:: ../doc_code/actor-sync.py

doc/source/ray-core/patterns/index.rst

@@ -12,6 +12,7 @@ This section is a collection of common design patterns and anti-patterns for wri
     generators
     limit-pending-tasks
     limit-running-tasks
+    actor-sync
     ray-get-loop
     unnecessary-ray-get
     ray-get-submission-order