Add handling for backpressure

Author: DarkArc

docs/howto/patterns.rst

@@ -93,11 +93,13 @@ In-process queue
 For simple applications that need to be able to consume and act on multiple
 messages at one, an in-process queue can be leveraged::
 
-    queue = asyncio.Queue()
+    MAX_WORKERS = os.cpu_count()
+
+    queue = asyncio.Queue(MAX_WORKERS)
 
     async def consumer_handler(websocket):
         for message in websocket:
-            queue.put(message)
+            await queue.put(message)
 
     async def worker():
         while True:
@@ -108,7 +110,7 @@ messages at one, an in-process queue can be leveraged::
     async def handler(websocket):
         async with asyncio.TaskGroup() as tg:
             tg.create_task(consumer_handler(websocket))
-            for _ in range(os.cpu_count()):
+            for _ in range(MAX_WORKERS):
                 tg.create_task(worker())
 
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