Skip to content

[None][fix] fix logprob in trtllm-serve - #6845

Open
jhaotingc wants to merge 1 commit into
NVIDIA:mainfrom
jhaotingc:fix_logprob_chat_completion
Open

jhaotingc wants to merge 1 commit into
NVIDIA:mainfrom
jhaotingc:fix_logprob_chat_completion

Conversation

@jhaotingc

@jhaotingc jhaotingc commented Aug 13, 2025 •

Copy link
Copy Markdown
Collaborator

logprobs is not correctly passed in from request.
Turned out to be request argument not passed in sampling param.

Thanks @Pernekhan for discovering this.

curl localhost:8001/v1/chat/completions -H "Content-Type: application/json" -d '{
        "model": "123",
        "messages": [{"role": "user", "content": "Why is NVIDIA a great company?"}],
        "logprobs": true
    }' -w "\n"
  File "/usr/local/lib/python3.12/dist-packages/tensorrt_llm/serve/postprocess_handlers.py", line 230, in chat_response_post_processor
    choice.logprobs = create_logprobs(output.token_ids, args.tokenizer, output.logprobs)
                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/dist-packages/tensorrt_llm/serve/postprocess_handlers.py", line 63, in create_logprobs
    assert len(token_ids) == len(logprobs), \
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: token_ids and logprobs have different lengths

Summary by CodeRabbit

  • New Features

    • Improved per-token log probability reporting for completions.
  • Bug Fixes

    • Corrected assignment of per-token logprobs to ensure values align with the corresponding token IDs.
  • Refactor

    • Renamed SamplingParams parameter from _return_log_probs to logprobs for clarity; update any integrations relying on the old name.

Description

Test Coverage

GitHub Bot Help

/bot [-h] ['run', 'kill', 'skip', 'reuse-pipeline'] ...

Provide a user friendly way for developers to interact with a Jenkins server.

Run /bot [-h|--help] to print this help message.

See details below for each supported subcommand.

Details

run [--reuse-test (optional)pipeline-id --disable-fail-fast --skip-test --stage-list "A10-PyTorch-1, xxx" --gpu-type "A30, H100_PCIe" --test-backend "pytorch, cpp" --add-multi-gpu-test --only-multi-gpu-test --disable-multi-gpu-test --post-merge --extra-stage "H100_PCIe-TensorRT-Post-Merge-1, xxx" --detailed-log --debug(experimental)]

Launch build/test pipelines. All previously running jobs will be killed.

--reuse-test (optional)pipeline-id (OPTIONAL) : Allow the new pipeline to reuse build artifacts and skip successful test stages from a specified pipeline or the last pipeline if no pipeline-id is indicated. If the Git commit ID has changed, this option will be always ignored. The DEFAULT behavior of the bot is to reuse build artifacts and successful test results from the last pipeline.

--disable-reuse-test (OPTIONAL) : Explicitly prevent the pipeline from reusing build artifacts and skipping successful test stages from a previous pipeline. Ensure that all builds and tests are run regardless of previous successes.

--disable-fail-fast (OPTIONAL) : Disable fail fast on build/tests/infra failures.

--skip-test (OPTIONAL) : Skip all test stages, but still run build stages, package stages and sanity check stages. Note: Does NOT update GitHub check status.

--stage-list "A10-PyTorch-1, xxx" (OPTIONAL) : Only run the specified test stages. Examples: "A10-PyTorch-1, xxx". Note: Does NOT update GitHub check status.

--gpu-type "A30, H100_PCIe" (OPTIONAL) : Only run the test stages on the specified GPU types. Examples: "A30, H100_PCIe". Note: Does NOT update GitHub check status.

--test-backend "pytorch, cpp" (OPTIONAL) : Skip test stages which don't match the specified backends. Only support [pytorch, cpp, tensorrt, triton]. Examples: "pytorch, cpp" (does not run test stages with tensorrt or triton backend). Note: Does NOT update GitHub pipeline status.

--only-multi-gpu-test (OPTIONAL) : Only run the multi-GPU tests. Note: Does NOT update GitHub check status.

--disable-multi-gpu-test (OPTIONAL) : Disable the multi-GPU tests. Note: Does NOT update GitHub check status.

--add-multi-gpu-test (OPTIONAL) : Force run the multi-GPU tests in addition to running L0 pre-merge pipeline.

--post-merge (OPTIONAL) : Run the L0 post-merge pipeline instead of the ordinary L0 pre-merge pipeline.

--extra-stage "H100_PCIe-TensorRT-Post-Merge-1, xxx" (OPTIONAL) : Run the ordinary L0 pre-merge pipeline and specified test stages. Examples: --extra-stage "H100_PCIe-TensorRT-Post-Merge-1, xxx".

--detailed-log (OPTIONAL) : Enable flushing out all logs to the Jenkins console. This will significantly increase the log volume and may slow down the job.

--debug (OPTIONAL) : Experimental feature. Enable access to the CI container for debugging purpose. Note: Specify exactly one stage in the stage-list parameter to access the appropriate container environment. Note: Does NOT update GitHub check status.

For guidance on mapping tests to stage names, see docs/source/reference/ci-overview.md
and the scripts/test_to_stage_mapping.py helper.

kill

kill

Kill all running builds associated with pull request.

skip

skip --comment COMMENT

Skip testing for latest commit on pull request. --comment "Reason for skipping build/test" is required. IMPORTANT NOTE: This is dangerous since lack of user care and validation can cause top of tree to break.

reuse-pipeline

reuse-pipeline

Reuse a previous pipeline to validate current commit. This action will also kill all currently running builds associated with the pull request. IMPORTANT NOTE: This is dangerous since lack of user care and validation can cause top of tree to break.

@coderabbitai

coderabbitai Bot commented Aug 13, 2025 •

Copy link
Copy Markdown
Contributor
📝 Walkthrough

Walkthrough

CompletionRequest.to_sampling_params now supplies a renamed boolean parameter logprobs to SamplingParams. Postprocessing (create_logprobs) now reads per-token logprob from indexable objects (logprob[token_id].logprob) and clamps values with a floor of -9999.0.

Changes

Cohort / File(s) Summary of Changes
OpenAI protocol → SamplingParams
tensorrt_llm/serve/openai_protocol.py
CompletionRequest.to_sampling_params now calls SamplingParams(logprobs=bool(self.logprobs)) (parameter renamed from _return_log_probs → logprobs).
Postprocess logprobs handling
tensorrt_llm/serve/postprocess_handlers.py
create_logprobs now expects indexable objects and uses logprob[token_id].logprob for per-token values, then applies max(value, -9999.0) to clamp low probabilities.

Sequence Diagram(s)

(omitted — changes are parameter rename and per-token value extraction; no new control-flow warranting a sequence diagram)

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Suggested reviewers

  • tongyuantongyu
  • kaiyux
  • LinPoly

📜 Recent review details

Configuration used: .coderabbit.yaml
Review profile: CHILL
Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between f835571 and 628774d.

📒 Files selected for processing (2)
  • tensorrt_llm/serve/openai_protocol.py (1 hunks)
  • tensorrt_llm/serve/postprocess_handlers.py (1 hunks)
🚧 Files skipped from review as they are similar to previous changes (2)
  • tensorrt_llm/serve/postprocess_handlers.py
  • tensorrt_llm/serve/openai_protocol.py
⏰ Context from checks skipped due to timeout of 90000ms. You can increase the timeout in your CodeRabbit configuration to a maximum of 15 minutes (900000ms). (1)
  • GitHub Check: Pre-commit Check
✨ Finishing Touches
  • 📝 Generate Docstrings
🧪 Generate unit tests
  • Create PR with unit tests
  • Post copyable unit tests in a comment

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share
🪧 Tips

Chat

There are 3 ways to chat with CodeRabbit:

  • Review comments: Directly reply to a review comment made by CodeRabbit. Example:
    • I pushed a fix in commit <commit_id>, please review it.
    • Open a follow-up GitHub issue for this discussion.
  • Files and specific lines of code (under the "Files changed" tab): Tag @coderabbitai in a new review comment at the desired location with your query.
  • PR comments: Tag @coderabbitai in a new PR comment to ask questions about the PR branch. For the best results, please provide a very specific query, as very limited context is provided in this mode. Examples:
    • @coderabbitai gather interesting stats about this repository and render them as a table. Additionally, render a pie chart showing the language distribution in the codebase.
    • @coderabbitai read the files in the src/scheduler package and generate a class diagram using mermaid and a README in the markdown format.

Support

Need help? Create a ticket on our support page for assistance with any issues or questions.

CodeRabbit Commands (Invoked using PR/Issue comments)

Type @coderabbitai help to get the list of available commands.

Other keywords and placeholders

  • Add @coderabbitai ignore anywhere in the PR description to prevent this PR from being reviewed.
  • Add @coderabbitai summary to generate the high-level summary at a specific location in the PR description.
  • Add @coderabbitai or @coderabbitai title anywhere in the PR title to generate the title automatically.

Status, Documentation and Community

  • Visit our Status Page to check the current availability of CodeRabbit.
  • Visit our Documentation for detailed information on how to use CodeRabbit.
  • Join our Discord Community to get help, request features, and share feedback.
  • Follow us on X/Twitter for updates and announcements.

@jhaotingc
jhaotingc force-pushed the fix_logprob_chat_completion branch from d4c4d9a to f835571 Compare August 13, 2025 00:07
@jhaotingc

Copy link
Copy Markdown
Collaborator Author

/bot run

@jhaotingc
jhaotingc requested review from LinPoly and syuoni August 13, 2025 00:07
@jhaotingc jhaotingc changed the title [None][fix] fix logprob [None][fix] fix logprob in trtllm-serve Aug 13, 2025
@tensorrt-cicd

Copy link
Copy Markdown
Collaborator

PR_Github #15034 [ run ] triggered by Bot

@jhaotingc

Copy link
Copy Markdown
Collaborator Author

/bot kill

@coderabbitai coderabbitai Bot left a comment

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Actionable comments posted: 1

🔭 Outside diff range comments (1)
tensorrt_llm/serve/postprocess_handlers.py (1)

60-73: Fix create_logprobs crash, normalize return_logprobs & add NVIDIA header

The current create_logprobs will fail when passed a flat List[float] or a mapping without the expected .logprob structure, and ChatPostprocArgs.from_request can receive an integer/None for return_logprobs. Also, the file needs the standard NVIDIA header.

Please apply the following changes:

• tensorrt_llm/serve/postprocess_handlers.py – update create_logprobs signature and body to handle:

  • legacy floats
  • dicts mapping token IDs to floats or objects with .logprob
  • indexable sequences
    • tensorrt_llm/serve/postprocess_handlers.py – in ChatPostprocArgs.from_request, cast request.logprobs to bool
    • tensorrt_llm/serve/postprocess_handlers.py – insert the standard NVIDIA copyright header at the top

Proposed diffs:

--- a/tensorrt_llm/serve/postprocess_handlers.py
+++ b/tensorrt_llm/serve/postprocess_handlers.py
@@ –1,0 +1,8 @@
+# =============================================================================
+# Copyright (c) 2025, NVIDIA CORPORATION.
+# Licensed under the Apache License, Version 2.0 (the “License”);
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#     http://www.apache.org/licenses/LICENSE-2.0
+# =============================================================================

@@ -60,7 +68,7 @@ def create_logprobs(token_ids: List[int],
-                    logprobs: List[float]) -> ChatCompletionLogProbs:
+                    logprobs: List[object]) -> ChatCompletionLogProbs:
     assert len(token_ids) == len(logprobs), \
             "token_ids and logprobs have different lengths"
     content: List[ChatCompletionLogProbsContent] = []
-    for token_id, logprob in zip(token_ids, logprobs):
+    for token_id, step_logprob in zip(token_ids, logprobs):
         token = tokenizer.decode(token_id)
         # returning multiple logprobs is not supported
+        # support float, dict[int,Obj], and indexable sequences
         try:
             if isinstance(step_logprob, (int, float)):
                 lp = float(step_logprob)
@@ -78,13 +86,23 @@ def create_logprobs(token_ids: List[int],
             else:
                 # sequence or mapping
                 cand = step_logprob[token_id]
-                lp = float(getattr(cand, "logprob", cand))
+                lp = float(getattr(cand, "logprob", cand))
         except Exception:
             lp = None
-        if lp is None or not isinstance(lp, (float, int)):
-            lp = -9999.0
-        lp = max(lp, -9999.0)
+        if not isinstance(lp, (int, float)):
+            lp = -9999.0
+        lp = max(lp, -9999.0)
         first_logprob = ChatCompletionLogProbsContent(
             token=token,
             logprob=lp,
             bytes=list(token.encode("utf-8", errors="replace")))
         content.append(first_logprob)
--- a/tensorrt_llm/serve/postprocess_handlers.py
+++ b/tensorrt_llm/serve/postprocess_handlers.py
@@ class ChatPostprocArgs(PostprocArgs):
-        return cls(
+        return cls(
             echo=request.echo,
             role="assistant" if request.add_generation_prompt else request.messages[-1]["role"],
             model=request.model,
             num_choices=request.n,
             tools=request.tools,
             tool_choice=request.tool_choice,
             stream_options=request.stream_options,
-            return_logprobs=request.logprobs,
+            return_logprobs=bool(request.logprobs),
             last_message_content=None,
             reasoning_parser=request.reasoning_parser,
             reasoning_parser_dict={},
         )
📜 Review details

Configuration used: .coderabbit.yaml
Review profile: CHILL
Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between bd9a6dd and f835571.

📒 Files selected for processing (2)
  • tensorrt_llm/serve/openai_protocol.py (1 hunks)
  • tensorrt_llm/serve/postprocess_handlers.py (1 hunks)
🧰 Additional context used
📓 Path-based instructions (2)
**/*.py

📄 CodeRabbit Inference Engine (CODING_GUIDELINES.md)

**/*.py: Python code must target Python 3.8+
Python indentation: 4 spaces, no tabs
Maintain module namespace in imports (from package.subpackage import foo; then use foo.SomeClass())
Python file names use snake_case
Python class names use PascalCase
Python functions/methods and local variables use snake_case; variables starting with a number get k_ prefix (e.g., k_99th_percentile)
Global variables use G_ prefixed UPPER_SNAKE_CASE (e.g., G_MY_GLOBAL)
Constants use UPPER_SNAKE_CASE in Python
Avoid shadowing variables from outer scopes in Python
Initialize all externally visible members of a Python class in init
Prefer docstrings for interfaces used outside a file; comments for local code
Use Google-style docstrings for classes and functions (Sphinx-parsable)
Document attributes/variables inline with short docstrings
Avoid reflection when simple alternatives exist (e.g., prefer explicit parameters over dict(**locals()))
In try/except, catch the narrowest exceptions possible
For duck-typing with try/except, keep try body minimal and put logic in else

Files:

  • tensorrt_llm/serve/postprocess_handlers.py
  • tensorrt_llm/serve/openai_protocol.py
**/*.{cpp,cxx,cc,cu,h,hpp,hxx,hh,cuh,py}

📄 CodeRabbit Inference Engine (CODING_GUIDELINES.md)

Prepend NVIDIA copyright header (current year) to all source files

Files:

  • tensorrt_llm/serve/postprocess_handlers.py
  • tensorrt_llm/serve/openai_protocol.py
⏰ Context from checks skipped due to timeout of 90000ms. You can increase the timeout in your CodeRabbit configuration to a maximum of 15 minutes (900000ms). (1)
  • GitHub Check: Pre-commit Check

Comment thread tensorrt_llm/serve/openai_protocol.py Outdated
Comment on lines 590 to 593
# TODO: migrate to use logprobs and prompt_logprobs
_return_log_probs=bool(self.logprobs),
logprobs=bool(self.logprobs)
)

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

💡 Verification agent

🧩 Analysis chain

Duplication of logprobs flags; also AI summary inconsistency

You’re now setting both _return_log_probs and logprobs based on bool(self.logprobs). If both are consumed downstream, this is fine short-term, but it’s easy for them to drift semantically. Please confirm the backend reads the new logprobs flag and plan deprecating _return_log_probs.

Note: The AI summary says CompletionRequest gained logprobs=..., but the actual change is in ChatCompletionRequest. Flagging for clarity.

Additionally, the file is missing the standard NVIDIA copyright header required by the coding guidelines.

Run this to verify SamplingParams has a logprobs field and to spot downstream usage:

Optional type alignment (outside this hunk): the Chat API’s logprobs input is effectively boolean in your usage. Consider allowing both bool/int for compatibility.

# openai_protocol.py (suggested outside this hunk)
# Change ChatCompletionRequest field typing to accept both:
logprobs: Optional[Union[bool, int]] = None

🏁 Script executed:

#!/bin/bash
set -euo pipefail

echo "Check SamplingParams definition includes 'logprobs'..."
rg -n "class SamplingParams" -A 20 tensorrt_llm | sed -n '1,120p' | rg -n "logprobs\s*:"

echo
echo "Callsites constructing SamplingParams with 'logprobs' param..."
rg -n "SamplingParams\\(.+logprobs\\s*=" -A 2

echo
echo "Downstream usage of SamplingParams.logprobs..."
rg -n "SamplingParams(?![\\s\\S]*class).*" -n
rg -n "\\.logprobs\\b" tensorrt_llm | rg -v "openai_protocol\\.py"

Length of output: 233


🏁 Script executed:

#!/bin/bash
set -euo pipefail

echo "Searching for class SamplingParams across the repo..."
rg -n "class SamplingParams" -A 20 .

echo
echo "Searching for any references to SamplingParams..."
rg -n "SamplingParams" -A 2 .

echo
echo "Searching for usage of .logprobs outside openai_protocol.py..."
rg -n "\.logprobs\b" . | rg -v "openai_protocol\.py"

Length of output: 271470


Align ChatCompletionRequest logprobs flag and update summary

  • Verify that the new logprobs field on ChatCompletionRequest (not _return_log_probs) is actually forwarded in to_sampling_params and respected by the backend. Once confirmed, plan to deprecate and remove _return_log_probs.
  • Correct the AI summary so it refers to ChatCompletionRequest.logprobs (the change is in the chat API, not CompletionRequest).
  • Add the standard NVIDIA copyright header to the top of tensorrt_llm/serve/openai_protocol.py.
🤖 Prompt for AI Agents
In tensorrt_llm/serve/openai_protocol.py around lines 590 to 593, update to
forward the new ChatCompletionRequest.logprobs flag (not the legacy
_return_log_probs) into to_sampling_params so the backend receives and respects
ChatCompletionRequest.logprobs; keep backward-compatible handling if needed but
mark _return_log_probs deprecated and plan its removal. Also correct the AI
summary text to reference ChatCompletionRequest.logprobs (chat API) instead of
CompletionRequest, and add the standard NVIDIA copyright header at the top of
this file.

@tensorrt-cicd

Copy link
Copy Markdown
Collaborator

PR_Github #15035 [ kill ] triggered by Bot

@tensorrt-cicd

Copy link
Copy Markdown
Collaborator

PR_Github #15034 [ run ] completed with state ABORTED

@tensorrt-cicd

Copy link
Copy Markdown
Collaborator

PR_Github #15035 [ kill ] completed with state SUCCESS
Successfully killed previous jobs for commit f835571

Signed-off-by: Jhao-Ting Chen <jhaotingc@nvidia.com>
@jhaotingc
jhaotingc force-pushed the fix_logprob_chat_completion branch from f835571 to 628774d Compare August 13, 2025 00:20
@jhaotingc

Copy link
Copy Markdown
Collaborator Author

/bot run --disable-fail-fast

@tensorrt-cicd

Copy link
Copy Markdown
Collaborator

PR_Github #15036 [ run ] triggered by Bot

@tensorrt-cicd

Copy link
Copy Markdown
Collaborator

PR_Github #15036 [ run ] completed with state SUCCESS
/LLM/main/L0_MergeRequest_PR pipeline #11356 completed with status: 'FAILURE'

@LinPoly LinPoly left a comment

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Correct me if I am wrong, but #6097 seems like a more comprehensive solution.

first_logprob = ChatCompletionLogProbsContent(
token=token,
logprob=max(logprob, -9999.0),
logprob=max(logprob[token_id].logprob, -9999.0),

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

This will break TRT flow IIRC.

@jhaotingc jhaotingc Aug 13, 2025 •

Copy link
Copy Markdown
Collaborator Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I didn't test, but that's the data format I got after I sent "logprobs": true to /v1/chat/completions, for both torch and trt sampler.

What's the way to sent the curl and have you checked if 6097 fix the issue (correctly get logprob from pytorch flow).

If you've verified the function works on 6097, we don't need this fix. Thanks!!

@LinPoly

LinPoly commented Aug 13, 2025

Copy link
Copy Markdown
Collaborator

@jhaotingc can you pls give the launch server command to reproduce the bug? I can check if it is a known issue.

@jhaotingc

Copy link
Copy Markdown
Collaborator Author

@LinPoly sure. Basically any model has this. Torch/TRT sample has this error too.
Haven't tried cpp backend.

BASE_MODEL="/trt_llm/data/llm-models/Qwen3/Qwen3-32B-FP8"
# BASE_MODEL="/scratch_1/tmp/modelopt/saved_models_Qwen3-32B_fp8_hf"

cat > extra-llm-api-config.yml <<EOF
enable_chunked_prefill: false
cuda_graph_config: 
    batch_sizes: [1,2,4,8,16,29,30,31,32]
    enable_padding: true
use_torch_sampler: false
EOF

TRTLLM_FORCE_XQA=1 \
TRT_LLM_DISABLE_LOAD_WEIGHTS_IN_PARALLEL=1 \
trtllm-serve $BASE_MODEL \
        --backend pytorch \
        --tp_size 1 \
        --host 0.0.0.0 \
        --port 8001 \
        --kv_cache_free_gpu_memory_fraction 0.95 \
        --max_batch_size 32 \
        --max_num_tokens 3072 \
        --max_seq_len 3072 \
        --extra_llm_api_options extra-llm-api-config.yml > out.log &

@juney-nvidia

Copy link
Copy Markdown
Collaborator

@jhaotingc Hi Jhao-ting,

Do you still want to land this PR to ToT or you want to close it directly?

Thanks
June

@github-actions

Copy link
Copy Markdown

@jhaotingc this pull request has had no activity for more than 120 days and currently has merge conflicts. Is it still active? Please resolve the conflicts or post an update. Otherwise, it will be closed after another 60 days of inactivity.

This branch has not been deployed

No deployments
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Labels

None yet

Projects

None yet

Development

Successfully merging this pull request may close these issues.

4 participants