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[Frontend][RL] Add a weight checker dev endpoint - #51350
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This pull request has merge conflicts that must be resolved before it can be |
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please make a declaration of difference between this pr and #45586 |
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| (RoPE sin/cos caches recomputed from config) are skipped because they | ||
| vary across restarts even when weights are unchanged. | ||
| """ | ||
| import hashlib |
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move this import on top of the module
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| def _tp_args(tp: int) -> list[str]: | ||
| # TP=1 needs no extra flags; TP>1 launches a tensor-parallel server. | ||
| return [] if tp == 1 else ["--tensor-parallel-size", str(tp)] |
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move _wc and _tp_args to conftest.py
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| for name, tensor in _iter_checksum_targets(self.model_runner.model): | ||
| raw = tensor.data.contiguous().cpu().view(torch.uint8).numpy().tobytes() | ||
| checksums[f"{tp_rank}:{name}"] = hashlib.sha256(raw).hexdigest() |
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we should use f"dp={dp_rank}/pp={pp_rank}/tp={tp_rank}/ep={ep_rank}:{name}", not just tp_rank, or it will make a duplicated value.
| if tensor.is_floating_point(): | ||
| tensor_ = torch.randn_like(tensor) | ||
| if tensor.dtype == torch.bool: | ||
| tensor_ = torch.randint_like(tensor, 0, 2, dtype=torch.bool) |
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we should also handle int data here.
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the last is int data process
| def test_world_size_matches_tp(self, wc_server): | ||
| tp, url = wc_server | ||
| ws = get_world_size(url, include_dp=False).json()["world_size"] | ||
| assert ws == tp, f"expected world_size {tp}, got {ws}" |
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this is invalid test, please remove it
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| Use case in RL: call ``snapshot`` right before a weight update, then | ||
| ``compare`` after ``finish_weight_update`` to verify the engine's weights | ||
| actually changed (non-zero NCCL transfer). |
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normal case is snapshot -> reset -> compare
| """snapshot / compare / checksum lifecycle on ONE shared server per TP.""" | ||
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| def test_compare_without_snapshot_returns_400(self, wc_server): | ||
| # Runs first per TP: a freshly-booted server has no snapshot yet. |
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you want to share server between test cases, but please don't assume test_compare_without_snapshot_returns_400 is executed firstly, you need to find a more elegant way to solve the problem
| body = r.json() | ||
| assert body["status"] == "snapshotted" | ||
| assert isinstance(body["n_tensors"], int) | ||
| assert body["n_tensors"] > 0, f"expected > 0 tensors, got {body}" |
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we could remove this case.
| tp, url = wc_server | ||
| r1 = _wc(url, "checksum").json()["checksums"] | ||
| r2 = _wc(url, "checksum").json()["checksums"] | ||
| assert r1 == r2, "checksum not stable: same weights, different digests" |
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combine this case with test_checksum_returns_dict_of_hex and refine it.
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it's better to add an example to show how rlhf use weiht checker |
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please support a report about time cost of weight checker for qwen3-30B. |
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Documentation preview: https://vllm--51350.org.readthedocs.build/en/51350/ |
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| @@ -356,7 +256,18 @@ def health(url) -> int: | |||
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| # --------------------------------------------------------------------------- | |||
| # HTTP helpers — weight transfer | |||
| # HTTP helpers 閳?weight checker | |||
| # --------------------------------------------------------------------------- | |||
| ``` | ||
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| After a successful weight transfer, the expected verification result is | ||
| `match: false`, together with one or more entries in `mismatches`, because the |
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we should use the same weight to update_weight after reset weight, then we shoul assert match:true
| """ | ||
| for _, tensor in _iter_checksum_targets(self.model_runner.model): | ||
| if tensor.is_floating_point(): | ||
| tensor_ = torch.empty(shape, device=tensor.device, dtype=tensor.dtype) |
| tensor_ = torch.empty(shape, device=tensor.device, dtype=tensor.dtype) | ||
| # To avoid high memory usage | ||
| for chunk in tensor_.view(-1).split(64 * 1024 * 1024): | ||
| chunk.copy_(torch.rand(chunk.shape, device=tensor.device, dtype=torch.float32).to(tensor.dtype)) |
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is_floating_point已经判断是否为为浮点数，rand应该都是支持的，请检查是否需要先生成fp32数据再转回原数据类型
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✅ Triggered Buildkite CI #91798 for commit |
It only verifies RL weight updates, next to the weight transfer and layerwise reload docs. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Signed-off-by: aoshen02 <aoshen02@users.noreply.github.com>
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/ci run |
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✅ Triggered Buildkite CI #91803 for commit |
- Restore collective_rpc to main's behavior. Only checksums need every engine's result, so add a compute_weight_checksums utility that the async client calls per engine, like the elastic EP utilities. - Add POST /weight_checker to the Rust frontend, whose collective_rpc already gathers every engine. - Move the fan-out unit test next to the other DPLB client tests. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Signed-off-by: aoshen02 <aoshen02@users.noreply.github.com>
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Signed-off-by: aoshen02 <aoshen02@users.noreply.github.com>
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/ci run |
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✅ Triggered Buildkite CI #91868 for commit |
aoshen02
changed the title
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This pull request has merge conflicts that must be resolved before it can be |
Signed-off-by: aoshen02 <aoshen02@users.noreply.github.com>
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Signed-off-by: aoshen02 <aoshen02@users.noreply.github.com>
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/ci run |
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/ci run |
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✅ Triggered Buildkite CI #91996 for commit |
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✅ CI is already running for this commit: https://buildkite.com/vllm/ci/builds/91996 |
Purpose
Verify that an RL weight update (
start_weight_update → update_weights* → finish_weight_update) reached every engine and every parameter intact, so a silent partial update does not turn into off-policy training. RFC: #52689Design
One dev endpoint,
POST /weight_checker(requiresVLLM_SERVER_DEV_MODE=1), in both the Python and Rust frontends:{"action": "checksum"}{"checksums": {key: sha256_hex}}{"action": "reset"}{"status": "reset"}{"action": "compare", "baseline": {key: sha256_hex}}{"match": bool, "mismatches": [key]}dp{dp}:pp{pp}:pcp{pcp}:tp{tp}:{param_name}(the EP rank is determined by dp, pcp and tp). The DP part usesdata_parallel_index, because dense workers resetdata_parallel_rankto 0. Duplicate keys across workers return 500 instead of silently merging ranks.comparefail forever.SharedWeightParameterpartitions and tensor-subclass weights (e.g. TorchAOqdata/scale) are expanded into their inner tensors.resetzeroes the covered tensors in place throughcollective_rpc, the same path asupdate_weights.checksumandcompareuse a newEngineClient.compute_weight_checksums. The async client calls acompute_weight_checksumsengine utility on every managed engine throughcall_utility_all_async([Core] Combine per-engine utility results like the Rust client #59240) and concatenates the results.collective_rpcis unchanged: under DP load balancing it returns only the first engine's result, and each engine holds different shards. The Rust frontend'scollective_rpcalready gathers every engine, so its route calls it directly.checksumandcomparecan land on different processes.actionandbaselineare embedded body fields, like the neighboring endpoints. An unknown action orcomparewithoutbaselinereturns 400.Documented limitations (
docs/training/weight_checker.md): stay paused fromchecksumtocompare(EPLB moves experts while serving); send to every API server under external LB; draft models, LoRA adapters and buffers are not checked; CPU backends that repack linear weights, compressed-tensors online transforms,--offload-backend prefetch, and MoE padding beyond the checkpoint shape (DeepEP, MXFP4) are not supported; the engine must be awake.Depends on #57163: until it lands, compressed-tensors checkpoints expose the attention KV scales as parameters, so
resetzeroes them and nothing restores them.Not a duplicate
This is the existing PR for RFC #52689. No other open PR adds a weight-checksum endpoint.
Test Plan
SharedWeightParameterpartitions; tensor-subclass inner tensors; distinct dense-DP key prefixes; the DPLB client gathers checksums from every engine (tests/v1/engine/test_engine_core_client.py).rust/src/server/src/routes/tests.rs).comparereports changed and missing keys; reset →reload_weights→ match; reset → real IPC weight transfer over HTTP → match; DP=2 and TP=2 (2 GPUs): every worker rank is reported, reset, and restored.Test Result
cargo test -p vllm-server weight_checker); rustfmt and clippy clean.Float8WeightOnlyConfigchecksum/reset verified manually with torchao 0.18.AI assistance (Claude Code) was used for this change. The implementation went through ten rounds of adversarial review with Codex and Kimi K3 until both reported no findings. The submitter reviewed every changed line and ran the tests above.
🤖 Generated with Claude Code