fix(vllm): warn that stream interval is not respected for now

[alec-flowers]

Overview:

As titled

Details:

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Related Issues: (use one of the action keywords Closes / Fixes / Resolves / Relates to)

• closes GitHub issue: #xxx

Summary by CodeRabbit

• Documentation
  • Added a runtime warning when the --stream-interval parameter is configured to inform users that this setting is not supported and output buffering behavior differs from standard operation.

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[coderabbitai]

Walkthrough

A runtime warning was added to the parse_args function in the vLLM arguments module. The warning alerts users when stream_interval is configured to a non-default value, informing them that Dynamo does not respect this setting and vLLM's OutputProcessor buffering is bypassed on the frontend.

Changes

Cohort / File(s)	Summary
vLLM args validation components/src/dynamo/vllm/args.py	Added runtime warning when engine_args.stream_interval is set and differs from 1, clarifying that Dynamo ignores the --stream-interval flag and bypasses vLLM's output buffering

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~3 minutes

• Warning logic is straightforward and localized to a single location
• Check occurs in an appropriate location within the initialization flow
• Message clarity and wording may warrant brief validation

Poem

🐰 A little flag you set with care,
But Dynamo just doesn't dare,
To heed your stream-interval plea,
The buffer's gone, it's wild and free!
So here's a warning, loud and clear,
"This setting won't apply here, dear!" 🎯

Pre-merge checks

❌ Failed checks (2 warnings)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	The description is largely incomplete. It uses placeholder text 'As titled' for overview and contains template boilerplate without substantive details about the changes.	Complete the Overview section with a clear explanation of the issue. Fill in the Details section describing the warning implementation and update the Related Issues section with the actual GitHub issue number.
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	You can run @coderabbitai generate docstrings to improve docstring coverage.

✅ Passed checks (1 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately describes the main change: adding a warning that stream interval is not respected in vLLM integration.

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[coderabbitai]

Actionable comments posted: 0

🧹 Nitpick comments (1)

components/src/dynamo/vllm/args.py (1)

205-205: Remove trailing space.

There's a trailing space before the closing quote.

-            "bypassing vLLM's OutputProcessor buffering. "
+            "bypassing vLLM's OutputProcessor buffering."

📜 Review details

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 0e6bb7b and b6bdbf1.

📒 Files selected for processing (1)

• components/src/dynamo/vllm/args.py (1 hunks)

⏰ 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). (7)

• GitHub Check: vllm (arm64)
• GitHub Check: trtllm (arm64)
• GitHub Check: sglang (arm64)
• GitHub Check: operator (amd64)
• GitHub Check: operator (arm64)
• GitHub Check: Build and Test - dynamo
• GitHub Check: Mirror Repository to GitLab

🔇 Additional comments (1)

components/src/dynamo/vllm/args.py (1)

201-207: Defensive implementation with correct assumptions confirmed.

The warning implementation is solid. The use of hasattr() ensures backward compatibility across vLLM versions, and the condition correctly checks for non-default values—vLLM's stream_interval default is indeed 1. The message clearly explains why Dynamo doesn't respect this flag, noting it bypasses vLLM's OutputProcessor buffering with its own post-processing implementation.

No changes needed.