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[BugFix] Add sleep to fix tight loop and release GIL #29476

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Merged
njhill merged 3 commits into from
Dec 18, 2025
Merged

[BugFix] Add sleep to fix tight loop and release GIL #29476

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bf07ad6
add sleep to fix tight loop and release GIL
alec-flowers Nov 26, 2025
f66be46
Update vllm/v1/engine/core.py
alec-flowers Dec 17, 2025
9107dce
Merge branch 'main' into fix-tight-loop
njhill Dec 17, 2025
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7 changes: 7 additions & 0 deletions vllm/v1/engine/core.py
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Original file line number Diff line number Diff line change
Expand Up @@ -923,6 +923,13 @@ def _process_engine_step(self) -> bool:
# Post-step hook.
self.post_step(model_executed)

# If no model execution happened but there are waiting requests
# (e.g., WAITING_FOR_REMOTE_KVS), yield the GIL briefly to allow
# background threads (like NIXL handshake) to make progress.
# Without this, the tight polling loop can starve background threads.
if not model_executed and self.scheduler.has_unfinished_requests():
time.sleep(0.001)

return model_executed

def _handle_client_request(
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