fix(server): cancel and await producer task before cleanup to prevent GC warning (Fixes #1121)

.github/actions/spelling/allow.txt

@@ -1,4 +1,4 @@
 a2a
 A2A
 A2AFastAPI
 AAgent
@@ -28,7 +28,7 @@
 AUser
 autouse
 backticks
 base64url
 buf
 bufbuild
 cla
@@ -43,7 +43,7 @@
 drivername
 DSNs
 dunders
 ES256
 euo
 EUR
 evt
@@ -58,8 +58,8 @@
 gle
 GVsb
 hazmat
 HS256
 HS384
 ietf
 importlib
 initdb
@@ -100,10 +100,10 @@
 Oneof
 OpenAPI
 openapiv
 openapiv2
 opensource
 otherurl
 pb2
 podman
 Podman
 poolclass
@@ -126,7 +126,7 @@
 respx
 resub
 rmi
 RS256
 RUF
 SECP256R1
 SFIXED
@@ -150,4 +150,5 @@
 typeerror
 UIDs
 vulnz
+GC
 whl

src/a2a/server/agent_execution/active_task.py

@@ -36,6 +36,7 @@
 from __future__ import annotations
 
 import asyncio
+import contextlib
 import logging
 import uuid
 
@@ -577,6 +578,18 @@ async def _run_consumer(self) -> None:
             async with self._lock:
                 self._reference_count -= 1
             logger.debug('Consumer[%s]: Finishing', self._task_id)
+
+            # Cancel and await the producer before cleanup to prevent
+            # asyncio "Task was destroyed but it is pending!" warnings.
+            # Without this, the producer could still be parked on
+            # _request_queue.get() or inside its finally block when
+            # _maybe_cleanup() releases the ActiveTask reference,
+            # causing the still-pending task to be garbage-collected.
+            if self._producer_task and not self._producer_task.done():
+                self._producer_task.cancel()
+                with contextlib.suppress(asyncio.CancelledError):
+                    await self._producer_task
+
             await self._maybe_cleanup()
 
     async def subscribe(

tests/server/agent_execution/test_active_task.py

@@ -895,3 +895,95 @@ async def execute_mock(req, q):
     assert len(events) == 0
 
     await active_task.cancel(request_context)
+
+
+@pytest.mark.timeout(5)
+@pytest.mark.asyncio
+async def test_producer_cancelled_on_normal_completion():
+    """Verify producer is cancelled and awaited before cleanup to prevent GC warnings.
+
+    Regression test for #1121: when the consumer finishes first (normal
+    completion path), the producer must be cancelled and awaited before
+    _maybe_cleanup() releases the ActiveTask reference, otherwise asyncio
+    logs "Task was destroyed but it is pending!".
+    """
+    agent_executor = Mock()
+    task_manager = Mock()
+    cleanup_called = False
+
+    def on_cleanup(_task: ActiveTask) -> None:
+        nonlocal cleanup_called
+        cleanup_called = True
+
+    active_task = ActiveTask(
+        agent_executor=agent_executor,
+        task_id='test-task-id',
+        task_manager=task_manager,
+        on_cleanup=on_cleanup,
+    )
+
+    # Simulate a producer that blocks waiting for a request.
+    # The consumer will finish first (after processing all events),
+    # triggering normal teardown.
+    execute_started = asyncio.Event()
+    execute_barrier = asyncio.Event()
+
+    async def execute_mock(req, q):
+        execute_started.set()
+        # Block until released — simulates producer waiting for next request
+        await execute_barrier.wait()
+
+    agent_executor.execute = AsyncMock(side_effect=execute_mock)
+    agent_executor.cancel = AsyncMock()
+    task_manager.get_task = AsyncMock(
+        return_value=Task(
+            id='test-task-id',
+            status=TaskStatus(state=TaskState.TASK_STATE_WORKING),
+        )
+    )
+    task_manager.save_task_event = AsyncMock()
+    task_manager.ensure_task_id = AsyncMock(
+        return_value=Task(
+            id='test-task-id',
+            status=TaskStatus(state=TaskState.TASK_STATE_WORKING),
+        )
+    )
+    task_manager.process = AsyncMock(side_effect=lambda x: x)
+
+    request_context = Mock(spec=RequestContext)
+    request_context.call_context = ServerCallContext()
+    request_context.context_id = 'test-context'
+    request_context.message = None
+
+    await active_task.enqueue_request(request_context)
+    await active_task.start(
+        call_context=ServerCallContext(), create_task_if_missing=True
+    )
+
+    # Wait for producer to be executing
+    await execute_started.wait()
+
+    # Cancel the consumer to force consumer teardown while producer is pending.
+    # This simulates the normal-completion race: consumer finishes first,
+    # triggering _maybe_cleanup while producer is still parked.
+    if active_task._consumer_task:
+        active_task._consumer_task.cancel()
+        try:
+            await active_task._consumer_task
+        except asyncio.CancelledError:
+            pass
+
+    # Release the producer so it can complete its CancelledError/finally path
+    execute_barrier.set()
+
+    # Wait for producer to finish
+    await active_task._is_finished.wait()
+
+    # Verify producer was properly completed, not left pending
+    assert active_task._producer_task is not None
+    assert active_task._producer_task.done(), (
+        'Producer task should be done after consumer teardown'
+    )
+    assert cleanup_called, (
+        'on_cleanup should be called after producer is drained'
+    )