feat(poc): PoC-v2 sampler residual for vLLM 0.25.1 (1/2 — plugin base)#70
feat(poc): PoC-v2 sampler residual for vLLM 0.25.1 (1/2 — plugin base)#70baychak wants to merge 2 commits into
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Minimal in-tree surface the out-of-tree gonka-poc plugin needs on 0.25.1: per-request logprobs_mode + enforced_token_ids, need_processed_logprobs threading, mixed-mode sampling with post-sampling enforced-token override, InputBatch bookkeeping, structured-output graceful degradation, and V1 model-runner containment (vLLM 0.25 ships a parallel V2 runner whose own sampler would bypass this residual). Contract tests pin the private vLLM surfaces the residual depends on so an upstream refactor fails loudly before the next rebase. docker/Dockerfile.gonka-poc composes the full image: this residual + pip install gonka-poc (pinned to tag v0.1.0a0). All PoC compute logic stays in the plugin. Formatted with the repo's own ruff hooks (v0.14.0). PR 1/2 of the split requested in gonka-ai#66 (plugin + vLLM 0.25).
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Moved to draft — a self-review before asking anyone else to read this turned up defects in the shared (non-PoC) code paths. Not worth your time in this state; I will un-draft once they are fixed. What the review found, for transparency:
The base path (no enforced tokens, no per-request logprobs_mode) was traced line-by-line against upstream and is unchanged — the issues above are all conditional on specific configurations. |
Self-review findings in the residual, before asking for an outside review. fill_bitmask() returned early when grammar enforcement had been disabled for a request. The bitmask tensor is reused across steps, so leaving that row untouched applied whatever mask last occupied it -- in a shared batch, another request's grammar -- and constrained the request to an unrelated token set. It now fills the row with -1 (allow everything), which is how the manager already fills rows for requests that are not grammar-constrained. validate_tokens() had the same gap: after the FSM went out of sync it kept filtering draft tokens against it, so speculative acceptance would collapse to zero while grammar was nominally disabled. It now returns the tokens unchanged. The enforced-token override used a masked assignment guarded by mask.any(). Both the guard and boolean-mask indexing force a device sync, on every decode step, on the shared sampling path. torch.where does the same job without one. The mixed-mode logprobs flag was written into a device tensor element by element in a Python loop -- a separate copy and sync per request, up to max_num_seqs of them per step. Built on the host and transferred once instead. The V2 model runner has its own sampler that reads neither enforced tokens nor per-request logprobs mode, so under V2 such a request returned a plausible completion that enforced nothing -- a validator would treat it as a verified replay. The V2 sampler now rejects those requests. The Dockerfile still selects V1, but as a convenience default rather than the safety net it was standing in for, and its comment says so. Dockerfile: added a base-image version guard (overlaying .py from one minor onto .so from another either fails at import or half-works), dropped a duplicate scipy install, and removed the pip line that could downgrade fastapi and pydantic out from under the base image. Justified the insecure-serialization variable instead of leaving it unexplained. Contract tests rewritten: assertions now read structure and behaviour -- msgspec field sets, signatures, a real SamplingParams round-trip, the validator rejecting an invalid mode -- instead of grepping source text, which passed on comments and broke on reformatting. References an outside reader cannot resolve are gone, and the files carry SPDX headers so pre-commit passes. Same eight tests, none weakened. Verified: ruff check and ruff format clean; every touched file compiles; the structural assertions checked against the working tree with an AST pass.
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Closing in favour of #78 and the series that follows it. These were stacked but each opened against Restructured: #78 carries the production PoC logic to 0.25.1 with no behaviour change, so it can be reviewed as a port. Each defect found while porting then gets its own PR on top, one finding each, so any that turn out to be deliberate design can be rejected without touching the rest. Nothing here is lost — the content of this PR reappears in the series, with its own justification. |
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First of two PRs, splitting #66 as requested: plugin + vLLM 0.25 here, additional fixes in #71. DeepSeek needs no in-tree change at all — see below.
What this adds
The minimal in-tree surface the out-of-tree
gonka-pocplugin needs on 0.25.1:logprobs_mode+enforced_token_idssampling_params.py,v1/sample/metadata.pyneed_processed_logprobsthreadingv1/sample/ops/topk_topp_sampler.pyv1/sample/sampler.pyv1/worker/gpu_input_batch.pyv1/structured_output/*v1/worker/gpu/sample/sampler.pytests/contract/docker/Dockerfile.gonka-pocAll PoC compute logic — nonce partitioning, seeded RNG, Householder scoring, L2 and binomial validation — stays in the plugin. Only what has no public vLLM hook lives here.
This is a port, and I reviewed it before asking you to
The sampler logic is carried over from the production PoC implementation, so replay stays bit-compatible with what the network already runs. A self-review before opening this found real defects in that logic. Fixed here are the ones that do not change behaviour for correct requests:
fill_bitmaskleaked another request's mask. It returned early when grammar was disabled, and the bitmask tensor is reused across steps — so the row kept whatever mask last occupied it. In a shared batch that is a different request's grammar constraining this one. It now fills the row with-1, matching how the manager fills rows for requests that are not grammar-constrained.validate_tokenskept filtering against a desynced FSM, which collapses speculative acceptance to zero while grammar is nominally off.mask.any()plus boolean-mask indexing, on the shared sampling path.torch.wheredoes the same work without one.Defects that do change behaviour are deliberately not here; they follow as separate PRs, so that a port and a behaviour change never land in one diff:
logprobs_modeaggregated per batch rather than per request, andlogprobs_mode_overridealtering the speculative-decoding pathPlease do not cut a release from this PR alone — those fixes matter for correctness, they are just separable for review.
DeepSeek-V4
No change in this repository. Per-group KV metadata,
positions, and deterministic pseudo input-ids all live in the plugin. A new model not touching vLLM is the point of the split.Verification
ruff checkandruff formatclean on every touched file. Contract tests assert structure and behaviour — field sets, signatures, a realSamplingParamsround-trip, the validator rejecting an invalid mode — rather than grepping source text; they carry SPDX headers and reference only files that exist here.