Opaque HTTP rollout endpoint with publish-only delta sync#5
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nanjiangwill wants to merge 14 commits into
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Opaque HTTP rollout endpoint with publish-only delta sync#5nanjiangwill wants to merge 14 commits into
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jvmncs
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Ship only the changed bytes between weight syncs as a canonical HF delta checkpoint; rollout hosts apply it into a host-local checkpoint and reload via the vanilla update_weights_from_disk path. Replaces the NCCL delta transport from THUDM#1806 with a disk-only path that needs no engine-side delta support.
sync_local_checkpoint (was sync_weights) materializes the base lazily via the idempotent init_local_checkpoint instead of a background thread; record per-sync update time in update_weight_metrics; state the pre-read/pre-push hooks' purpose (non-POSIX filesystem coherence).
The actor's update_weights is already @timer-wrapped (perf/update_weights_time), so the per-sync total/publish/reload breakdown was duplicate instrumentation. Keep only the delta-specific metrics (density, wire bytes).
The delta scaffold reworked the update-weight args: delta requires --update-weight-transport=disk (was nccl-or-disk), needs --update-weight-local-checkpoint-dir, and the --update-weight-delta-dir compatibility alias is gone (the directory belongs to the transport, not the encoding). Drop the alias resolve/backfill/conflict tests, point the transport and colocate tests at the disk path, and cover the local-checkpoint requirement.
With the delta-dir alias gone, _resolve_update_weight_disk_dir no longer normalizes anything — it's a single transport-level check, so fold it into _validate_update_weight_args.
slime_validate_args validates everything else inline; the extracted _validate_update_weight_args was the lone exception. Fold it in and test it the same way as the other slime_validate_args checks (make_slime_validate_args).
Materialize the host-local checkpoint in a daemon thread at engine init so the one-time base copy overlaps sglang launch and the first rollout (which serves from init-loaded weights) instead of blocking the first delta reload. The first sync_local_checkpoint's init_local_checkpoint is idempotent and flock-guarded, so it either finds the copy done or blocks on the same lock — no join needed.
Add --rollout-endpoint-url to train against an elastic rollout fleet behind a single opaque HTTP endpoint (no per-engine handles). Generation routes to the URL; the disk-delta updater publishes each version to the shared disk dir and advances a `latest` pointer for the fleet to pull, instead of pushing via per-engine RPCs. Add-only: managed and external-addressed paths are unchanged. Requires delta mode + disk transport (the only cross-cluster channel) and is non-colocate. - abort: the endpoint cancels surplus when discarding; with --partial-rollout it drains so streaming tasks return their partials (closing each stream disconnects, which aborts the fleet-side request). Endpoint + --partial-rollout requires the streaming rollout, the only path that captures partials client-side. - streaming: record the weight version on an aborted partial so off-policy correction can weight it (update_from_meta_info is skipped without a finish_reason).
Add --custom-rollout-request-hook-path: a hook that can mutate each outgoing generate request (payload/headers/max_retries/retry_sleep) before it is sent, with rollout_id and evaluation context threaded in via rollout_request_context. Weight-version gating is left to the hook rather than a core arg: the right target version is loop-specific (it only equals rollout_id in the synchronous loop) and the useful knob — a staleness offset — isn't expressible as an enum. Thread retry_sleep through http_utils.post so a gating hook can back off while waiting for the fleet to load a version. A documented example hook shows min/exact weight-version gating.
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needed this for moonlight to be used w/ update_weight_from_disk_delta
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Stacked on the disk-level delta weight sync branch. Adds
--rollout-endpoint-urlto train against an elastic rollout fleet behind a single opaque HTTP endpoint — no per-engine handles, no router worker APIs.Three things follow from that one flag:
get_model_url); the rollout server holds no engines (reusesExternalRolloutServerwith empty engines); placement allocates 0 rollout GPUs.--update-weight-disk-dirand advances alatestpointer (via the existing pre-push commit hook), skipping the per-engineupdate_weights_from_disk/pause/resume RPCs. The fleet pulls and hot-loads on its own.--partial-rolloutthe streaming generation tasks self-break and return the partial trajectories for resumption (each tagged with the weight version it stopped at).The weight version each trajectory was generated with already flows back via sglang's
meta_info["weight_version"]intoSample.weight_versions, so staleness handling stays the algorithm's concern — unchanged here.Add-only: managed and external-addressed paths are byte-for-byte unchanged. Requires
--update-weight-mode delta --update-weight-transport disk(disk is the only cross-cluster channel; full checkpoints are too large, hence deltas) and is non-colocate;--partial-rolloutrequires the streaming generation path.Follow-ups (not in this PR): CPU-mockable unit tests for the new path, docs (external-rollout-engines / delta-weight-sync), and an e2e test against a mock pulling endpoint.