[astrogilda]

Summary

Adds a public aclose() teardown to ActiveTask, ActiveTaskRegistry, and
DefaultRequestHandlerV2 that force-drains the SDK-owned producer, consumer,
and dispatcher asyncio.Tasks so none are left pending at event-loop shutdown.

• ActiveTask.aclose() force-closes both event queues and cancels the producer
  and consumer tasks, then awaits them. It sets _is_finished under _lock, so
  it is mutually exclusive with start() (which refuses to spawn once
  _is_finished is set).
• ActiveTaskRegistry.aclose() marks the registry closed so get_or_create
  refuses new work, drains every active task, then awaits the in-flight
  _remove_task cleanup tasks. The lock is released before awaiting because
  _remove_task re-acquires it.
• DefaultRequestHandlerV2.aclose() delegates to the registry drain, for wiring
  into an ASGI lifespan / on_shutdown hook.

Why

Fixes #1101. At shutdown the ActiveTask producer can stay pending and surface
as Task was destroyed but it is pending!. The producer's finally calls
_event_queue_subscribers.close(immediate=False), which awaits join() on
every subscriber sink; an abandoned subscriber leaves an undrained sink, so the
join() never returns and the producer hangs. There is no public way to drain
these background tasks today. aclose() closes the queues with immediate=True,
which releases the wedged producer, and reaps the tasks.

The teardown always forces rather than exposing a graceful immediate=False
option, because that path inherits the documented close(immediate=False)
deadlock and a shutdown hook must be bounded.

Test plan

• uv run pytest tests/server/agent_execution/ tests/server/request_handlers/ tests/server/events/ — pass
• uv run pytest --cov=a2a --cov-fail-under=88 — pass
• ./scripts/lint.sh — ruff, ruff-format, and ty clean

New tests cover the registry drain, idempotency, empty registry, new-work
rejected after close, and an errored task being logged rather than propagated;
ActiveTask reaping a running producer and force-closing past an undrained
subscriber (the #1101 repro); and the handler drain.

Fixes #1101 🦕

[gemini-code-assist]

Code Review

This pull request introduces aclose() methods to ActiveTask, ActiveTaskRegistry, and DefaultRequestHandlerV2 to facilitate a bounded, force-closed teardown of background tasks and queues during server shutdown, preventing pending task warnings. It also adds comprehensive unit tests to verify the teardown behavior, idempotency, and error handling. The review feedback suggests explicitly shutting down self._request_queue in ActiveTask.aclose() to ensure proper cleanup of all queues if start() was never called or failed early.

Important

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[github-actions]

🧪 Code Coverage (vs main)

⬇️ Download Full Report

	Base	PR	Delta
src/a2a/server/agent_execution/active_task.py	95.32%	95.09%	🔴 -0.24%
src/a2a/server/agent_execution/active_task_registry.py	93.75%	96.61%	🟢 +2.86%
src/a2a/server/events/event_queue_v2.py	91.19%	91.28%	🟢 +0.09%
src/a2a/server/request_handlers/default_request_handler_v2.py	94.12%	94.17%	🟢 +0.05%
Total	92.95%	92.97%	🟢 +0.02%

Generated by coverage-comment.yml

[astrogilda]

Addressed the review suggestion: aclose() now shuts down _request_queue (immediate=True) first, covering the never-started case, with a test. CI is green on the new push. Ready for review whenever you have a moment @rohityan.

[astrogilda]

Rebased onto current main to clear the "behind" state after #1053 and the recent refactors. No content changes, and the full suite is green on the rebased branch.

Quick recap of where things stand: the approach was agreed in #1101 (thanks @rohityan), the one review finding (never-started request queue) is addressed with a test, and CI has been green since the July push. Ready for review whenever you have a moment.

[astrogilda]

@mykytanetipa Your finding is addressed in 0728696: the drain now happens at the root in EventQueueSource.close(), so every caller gets the guarantee, and there's a regression test for the subscriber-less immediate-close case. Pushed on the 17th, the day after your changes-requested review; details in the thread reply above.

The branch has also been rebased onto current main (the 1.1.1 release commit) with no content changes to the three PR commits, and the touched-area suite and ruff are clean.

Requesting a re-review, since the change this review asked for was pushed on the 17th and is in the current head.

[mykytanetipa]

@astrogilda thank you for the quick fix, I see that tests/server/agent_execution/test_active_task.py is conflicting with main. Can you please resolve it?

[astrogilda]

@mykytanetipa Done. Rebased onto current main and fixed the overlap in that test file. The teardown-warning test arunmm8335 landed in #1122 and our three drain tests cover different paths, so I kept all four. Green here: agent_execution plus request_handlers, 131 passed, ruff clean.

@rohityan if you get a minute: this is the third rebase forced by unrelated edits to the same test file (#1053, then #1122). We settled the design in #1101 and the one review note is handled, so a merge would spare us the next round. Happy to turn around anything you flag.

Edited 2026-08-20 to fix an attribution. The teardown-warning test in #1122 is arunmm8335's work, not mykytanetipa's; this said "your test" to the wrong person.