Fix: SQS polling_interval transport option ignored in async event loop #2439

[ChickenBenny]

Summary

Fixes #2439 — the polling_interval broker transport option was completely ignored for SQS. Regardless of whether any messages were received, the poller would immediately reschedule the next ReceiveMessage call via hub.call_soon(), causing SQS to be polled as fast as the network allows (limited only by wait_time_seconds long-polling).

Root Cause

The SQS transport has its own async event-loop path that bypasses the polling_interval sleep used by virtual.Transport.drain_events(). The call chain was:

basic_consume
  └─ _loop1(queue)
       └─ hub.call_soon(_schedule_queue)        # schedules immediately
            └─ _get_bulk_async(callback=promise(_loop1, (queue,)))
                 └─ SQS ReceiveMessage
                      └─ _on_messages_ready()   # no return value
                           └─ _loop1(queue)     # always call_soon → infinite tight loop

Two concrete bugs:

1. _loop1 always called hub.call_soon() — meaning the next poll was always scheduled immediately, regardless of whether the previous poll returned any messages.
2. _on_messages_ready had no return value — so the callback (_loop1) could never know whether messages were found, making it impossible to decide whether to wait.

Behaviour After Fix

Scenario	Before	After
Empty poll	Immediately polls again	Waits polling_interval seconds (default: 1s)
Successful poll	Immediately polls again	Immediately polls again ✓
polling_interval=0 or None	Immediately polls again	Immediately polls again ✓
First basic_consume call	Immediately polls	Immediately polls ✓
Custom polling_interval=5	Ignored	Waits 5 s between empty polls ✓

Related

• Closes SQS polling_interval broker transport option ignored. #2439
• Celery docs: https://docs.celeryq.dev/en/main/getting-started/backends-and-brokers/sqs.html#polling-interval
• hub.call_later API: kombu/asynchronous/hub.py — delegates to self.timer.call_after(delay, callback, args)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.29%. Comparing base (156e003) to head (cd9b510).
⚠️ Report is 6 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2489      +/-   ##
==========================================
+ Coverage   82.22%   82.29%   +0.07%     
==========================================
  Files          79       79              
  Lines       10077    10089      +12     
  Branches     1152     1152              
==========================================
+ Hits         8286     8303      +17     
+ Misses       1589     1584       -5     
  Partials      202      202              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.