fix: fix engine initialization fails with ValueError

[leejianwoo-collab]

Fix GLM-4.1V dummy video input generation failure

Problem

GLM-4.1V engine initialization fails with ValueError: t:1 must be larger than temporal_factor:2 during dummy video input generation.

Root Cause

1. Issue Location: vllm/model_executor/models/glm4_1v.py:995 in get_num_frames_with_most_features() function
2. Problem: Function returns max(max_frames_per_video, 1), which can return 1 when video token allocation is insufficient
3. Constraint Violation: GLM-4.1V's smart_resize function requires num_frames > temporal_factor=2 (strict inequality)
4. Failure: num_frames=1 violates 1 > 2, causing ValueError and engine core crash

Error Stack Trace

ValueError: t:1 must be larger than temporal_factor:2
RuntimeError: Engine core initialization failed. See root cause above. Failed core proc(s): {'EngineCore_DP0': 1}

Solution

Change the minimum fallback value from 1 to 3 in get_num_frames_with_most_features():

# Before (line 995)
return max(max_frames_per_video, 1)

# After (line 995)  
return max(max_frames_per_video, 3)

Why 3?

• GLM-4.1V constraint: num_frames > temporal_factor=2
• Minimum valid value: num_frames >= 3
• Our fix ensures: 3 > 2 ✓ (constraint satisfied)

Impact

• Fixes: GLM-4.1V engine initialization failure for text-only/image-only inference
• Scope: Only affects GLM-4.1V dummy video input generation fallback case
• Backward Compatible: No breaking changes to existing functionality
• Performance: Minimal impact - only affects edge case with insufficient video token allocation

Testing

• Verified fix addresses the specific constraint violation
• Existing GLM-4.1V tests should continue to pass
• Created test case to validate minimum frame count requirement

Related Issues

Fixes #30638

Checklist

• Identified root cause in get_num_frames_with_most_features()
• Implemented minimal fix changing fallback from 1 to 3
• Verified fix satisfies GLM-4.1V's num_frames > temporal_factor=2 constraint
• Created test case for validation
• Confirmed no impact on other model implementations

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[gemini-code-assist]

Code Review

This pull request correctly addresses a ValueError that occurs during GLM-4.1V engine initialization. The root cause, related to dummy video input generation, has been accurately identified, and the proposed fix of changing the minimum fallback value for frames is effective. My review includes one suggestion to enhance the code's maintainability by programmatically deriving this fallback value instead of using a hardcoded number.

[DarkLight1337]

Which model repo are you using and what is your transformers version? I can't seem to reproduce the problem even after hardcoding this method to return 1.