[CI][BugFix] Fix failure CI "amd-v1-sample-plus-logits-mi300-1"

[SoluMilken]

Purpose

Fix failure CI: amd-v1-sample-plus-logits-mi300-1
https://buildkite.com/vllm/ci/builds/65147/canvas?jid=019e06e7-5882-42b3-8c44-6723201294ea&tab=output
https://buildkite.com/vllm/ci/builds/65109/canvas?jid=019e0656-76cd-445e-8324-cfe4b042f924&tab=output
https://buildkite.com/vllm/ci/builds/65102/canvas?jid=019e0637-d718-43e0-b285-eaab513fd44e&tab=output

Root Cause

• The test relied on fork semantics: monkeypatched entry_points was expected to be visible in workers.
• ROCm CI uses spawn instead of fork, so spawned workers do not inherit the in-memory monkeypatch.
• As a result, the dummy logits processor entrypoint was not discovered in EngineCore/worker.
• The model generated normal tokens instead of the forced target token sequence.
• Recent subprocess failure propagation made the existing issue visible.

Test Plan

python -m pytest \
"tests/v1/logits_processors/test_custom_offline.py::test_custom_logitsprocs[CustomLogitprocSource.LOGITPROC_SOURCE_ENTRYPOINT]" \
"tests/v1/logits_processors/test_custom_online.py::test_custom_logitsprocs[server0-facebook/opt-125m]" \
-v \
-p no:warnings

Test Result

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• The purpose of the PR, such as "Fix some issue (link existing issues this PR will resolve)".
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• (Optional) The necessary documentation update, such as updating supported_models.md and examples for a new model.

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[gemini-code-assist]

Code Review

This pull request refactors the mocking of custom logits processor entry points in tests by replacing in-memory patching of importlib.metadata with a more robust mechanism that creates temporary .dist-info files and updates the PYTHONPATH. This ensures that mocked entry points are correctly discovered by spawned worker processes. Feedback was provided regarding the construction of the PYTHONPATH environment variable, as the current implementation could result in a trailing separator that inadvertently adds the current working directory to the search path, potentially leading to non-hermetic tests.

[claude]

Claude Code Review

This pull request is from a fork — automated review is disabled. A repository maintainer can comment @claude review to run a one-time review.

[SoluMilken]

Hi @afeldman-nm @dzhengAP could you please take a look?

This fixes the ROCm logits processor entrypoint test failures by replacing the in-process importlib.metadata.entry_points monkeypatch with a temporary real .dist-info/entry_points.txt. The old test relied on fork semantics, but ROCm runs these paths under spawn, so EngineCore/worker processes did not inherit the monkeypatch and failed to discover the dummy logits processor.

Thanks.

[dzhengAP]

@SoluMilken thanks!there is an earlier PR discussed to fix this fork issue. Are they similar? #42040

[SoluMilken]

Hi dzhengAP, they are almost the same. Let me close this PR.