fix: retry connection pool prewarm after failure

livekit-agents/livekit/agents/utils/connection_pool.py

@@ -173,7 +173,13 @@ def prewarm(self) -> None:
         This method starts a background task that creates a new connection if none exist.
         The task automatically cleans itself up when the connection pool is closed.
         """
-        if self._prewarm_task is not None or self._connections:
+        if self._prewarm_task is not None:
+            task = self._prewarm_task()
+            if task is not None and not task.done():
+                return
+            self._prewarm_task = None
+
+        if self._connections:
             return
 
         async def _prewarm_impl() -> None:

tests/test_connection_pool.py

@@ -142,3 +142,32 @@ async def failing_connect(timeout: float):
     ]
     assert warning_records
     assert warning_records[0].exception_type == "ConnectionError"
+
+
+@pytest.mark.asyncio
+async def test_prewarm_retries_after_failure():
+    attempts = 0
+
+    async def flaky_connect(timeout: float):
+        nonlocal attempts
+        attempts += 1
+        if attempts == 1:
+            raise ConnectionError("temporary prewarm failure")
+        return DummyConnection(attempts)
+
+    pool = ConnectionPool(connect_cb=flaky_connect)
+    pool.prewarm()
+    task = pool._prewarm_task()
+    assert task is not None
+    await task
+
+    assert attempts == 1
+    assert not pool._connections
+
+    pool.prewarm()
+    task = pool._prewarm_task()
+    assert task is not None
+    await task
+
+    assert attempts == 2
+    assert len(pool._available) == 1