Don't block the Ray transport loop on training RPCs - #104
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ray.get in forward_backward/step froze the in-process vLLM scheduler that shares RayTransport's event loop. Await ObjectRefs under a train-op lock so generate can progress and DP collectives stay single-flight. Co-authored-by: Cursor <cursoragent@cursor.com>
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Summary
ray.getinArcticRLRayServer.forward_backward/forward/step/save/load_checkpointwithawait asyncio.gather(same as the HTTP server) so the in-process vLLM request scheduler can keep running during train.asyncio.Lockso unblocking the loop cannot interleave two DP collectives.stepdoes not callray.getand that two in-flightsteps stay single-flight.This is independent of the TRL backend. On the current TRL branch the same commit is cherry-picked as
8339f97onfix/ray-transport-nonblocking-gatherfor a GSM8K Ray before/after.Test plan
pytest tests/common/test_ray_server_training_gather.pyfix/ray-transport-nonblocking-gathervstrl-training-client) — compare wall, step p50/p95, weight_sync p50, idlefwd_bwd+stepsucceeds (no new hang)Made with Cursor