time.sleep() inside async def blocks event loop in _push_messages

[Joaquinriosheredia]

Hi,

While analyzing the codebase with python-vibe-guard, I found a potential
issue in backend/services/messaging/message_service.py around line 241.

The function _push_messages is an async def that uses time.sleep(0.5)
as a throttle every 10 messages:

if (i + 1) % 10 == 0:
    time.sleep(0.5)

time.sleep() blocks the entire event loop for 500ms — not just the current
coroutine. If this worker also handles other concurrent tasks (HTTP requests,
other async operations), every batch of 10 notifications introduces a 500ms
pause across all concurrent traffic on that worker.

Suggested fix (one-line change):

if (i + 1) % 10 == 0:
    await asyncio.sleep(0.5)

This preserves the throttling behavior while allowing other coroutines to
run during the wait.

Tool used: python-vibe-guard —
AST-based runtime anti-pattern scanner validated on 902 real repositories.

[linear]

TECH-1246