perf: drop task wrapper in EventNamespace.emit_update, keep flush tick#6734
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perf: drop task wrapper in EventNamespace.emit_update, keep flush tick#6734Alek99 wants to merge 2 commits into
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Greptile SummaryThis PR simplifies state-update websocket emits while keeping the flush yield. The main changes are:
Confidence Score: 5/5This looks safe to merge.
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Reviews (2): Last reviewed commit: "chore: add news fragment for #6734" | Re-trigger Greptile |
Merging this PR will not alter performance
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Awaiting a freshly created task blocks the caller exactly like awaiting the coroutine directly, so the wrapper never provided the claimed non-blocking behavior -- it only added task creation/scheduling overhead (~4-7us, 2-3x) on every outgoing state update. The task wrapper did have one load-bearing side effect: it forced an event loop tick, giving the engineio writer task a chance to flush the queued packet before the caller resumes (important when a sync event handler blocks the loop right after yielding an interim update). Keep that guarantee with an explicit asyncio.sleep(0) after the emit, which is still ~2x cheaper than the task wrapper. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01Sns7EuBPYvfGCxRSRZ1bUx
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Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01Sns7EuBPYvfGCxRSRZ1bUx
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Type of change
Changes To Core Features:
EventNamespace.emit_updatewrapped the socket emit inasyncio.create_task(...)and then immediately awaited it, with a comment claiming the task "prevents the update from being blocked behind other coroutines". Awaiting a freshly created task blocks the caller exactly like awaiting the coroutine directly — the wrapper never provided any concurrency; it only added per-update task creation/scheduling overhead (plus an f-string task name with atime.time()call). Sinceemit_updateruns while the state lock is held (viamodify_state/ the event processor'semit_deltapath), that overhead was paid on every outgoing state update.The one load-bearing side effect of the wrapper (caught by
test_yield_state_update[click_yield_interim_value]on the first iteration of this PR): awaiting a fresh task forces an event-loop tick, which lets engineio's per-connection writer task flush the queued packet before the caller resumes.sio.emititself can complete without ever suspending (the packet is only put on a non-full queue), so a sync handler that blocks the loop right after yielding (e.g.yield→time.sleep(...)) would otherwise hold the interim update hostage in the write queue. The fix keeps that guarantee explicitly withawait asyncio.sleep(0)after the emit, with a regression note explaining why the tick must stay.Micro-benchmark (Python 3.13, replicating the exact await patterns with a stand-in emit coroutine, 20k iterations after warmup):
await asyncio.create_task(emit(...), name=f"...{time.time()}")await emit(...)+await asyncio.sleep(0)1.9x less overhead per outgoing update. A writer-task ordering simulation confirms the interim packet is flushed before a loop-blocking caller resumes in both the old and new versions (and is not flushed with a plain
await emit(...)alone — which is why the sleep(0) is load-bearing).Linear: ENG-10110
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https://claude.ai/code/session_01Sns7EuBPYvfGCxRSRZ1bUx