[luyiyun1021]

Dev Engineer Review

The change sets MASTER_ADDR to 127.0.0.1 in 26 VisualGen test files. This aligns the rendezvous address with the IPv4 loopback address used by the port probes and avoids localhost resolving to a different address family. No production code or public APIs changed.

QA Engineer Review

The changed tests cover VisualGen distributed initialization across attention, transformer, VAE, pipeline, and mapping tests. The supplied validation reports controlled checks for two LTX-2 initializer functions, Python AST parsing, and pre-commit checks passed. Full model parity and the other 24 initializers were not tested. Test-list registration was not established. Coverage verdict: needs follow-up.

Per-File QA Perspective

• tests/integration/defs/examples/visual_gen/test_visual_gen_multi_gpu.py: Changes the distributed worker rendezvous address. Verify the integration test starts workers through IPv4 loopback; test-list registration was not established.
• tests/unittest/_torch/visual_gen/multi_gpu/test_attn2d_attention.py: Changes the distributed worker rendezvous address for 2D attention. Test-list registration was not established.
• tests/unittest/_torch/visual_gen/multi_gpu/test_cosmos3_transformer_parallel.py: Changes the distributed worker rendezvous address for Cosmos3 transformer parallelism. Test-list registration was not established.
• tests/unittest/_torch/visual_gen/multi_gpu/test_flux2_transformer_parallel.py: Changes the distributed worker rendezvous address for Flux2 transformer parallelism. Test-list registration was not established.
• tests/unittest/_torch/visual_gen/multi_gpu/test_flux_tp.py: Changes the distributed worker rendezvous address for Flux tensor parallelism. Test-list registration was not established.
• tests/unittest/_torch/visual_gen/multi_gpu/test_flux_ulysses.py: Changes the distributed worker rendezvous address for Flux Ulysses parallelism. Test-list registration was not established.
• tests/unittest/_torch/visual_gen/multi_gpu/test_ltx2_async_ulysses.py: Changes the distributed worker rendezvous address for LTX-2 asynchronous Ulysses. Test-list registration was not established.
• tests/unittest/_torch/visual_gen/multi_gpu/test_ltx2_parallel_vae.py: Changes the distributed worker rendezvous address for LTX-2 parallel VAE. Test-list registration was not established.
• tests/unittest/_torch/visual_gen/multi_gpu/test_ltx2_ulysses.py: Changes the distributed worker rendezvous address for LTX-2 Ulysses. Test-list registration was not established.
• tests/unittest/_torch/visual_gen/multi_gpu/test_parallel_attention.py: Changes the distributed worker rendezvous address for parallel attention. Test-list registration was not established.
• tests/unittest/_torch/visual_gen/multi_gpu/test_parallel_conv.py: Changes the distributed worker rendezvous address for parallel convolution. Test-list registration was not established.
• tests/unittest/_torch/visual_gen/multi_gpu/test_parallel_group_norm.py: Changes the distributed worker rendezvous address for parallel group normalization. Test-list registration was not established.
• tests/unittest/_torch/visual_gen/multi_gpu/test_parallel_vae.py: Changes the distributed worker rendezvous address for parallel VAE. Test-list registration was not established.
• tests/unittest/_torch/visual_gen/multi_gpu/test_qwen_image_attention_parallel.py: Changes the distributed worker rendezvous address for Qwen image parallel attention. Test-list registration was not established.
• tests/unittest/_torch/visual_gen/multi_gpu/test_ring_attention.py: Changes the distributed worker rendezvous address for ring attention. Test-list registration was not established.
• tests/unittest/_torch/visual_gen/multi_gpu/test_tp_attention.py: Changes the distributed worker rendezvous address for tensor-parallel attention. Test-list registration was not established.
• tests/unittest/_torch/visual_gen/multi_gpu/test_ulysses_async.py: Changes the distributed worker rendezvous address for asynchronous Ulysses. Test-list registration was not established.
• tests/unittest/_torch/visual_gen/multi_gpu/test_ulysses_attention.py: Changes the distributed worker rendezvous address for Ulysses attention. Test-list registration was not established.
• tests/unittest/_torch/visual_gen/multi_gpu/test_ulysses_sage_attention.py: Changes the distributed worker rendezvous address for Ulysses Sage attention. Test-list registration was not established.
• tests/unittest/_torch/visual_gen/multi_gpu/test_visual_gen_mapping.py: Changes the distributed worker rendezvous address for VisualGen mapping tests. Test-list registration was not established.
• tests/unittest/_torch/visual_gen/multi_gpu/test_wan_async_ulysses.py: Changes the distributed worker rendezvous address for Wan asynchronous Ulysses. Test-list registration was not established.
• tests/unittest/_torch/visual_gen/multi_gpu/test_wan_pipeline_parallel.py: Changes the distributed worker rendezvous address for Wan pipeline parallelism. Test-list registration was not established.
• tests/unittest/_torch/visual_gen/multi_gpu/test_wan_tp.py: Changes the distributed worker rendezvous address for Wan tensor parallelism. Test-list registration was not established.
• tests/unittest/_torch/visual_gen/multi_gpu/test_wan_transformer_parallel.py: Changes the distributed worker rendezvous address for Wan transformer parallelism. Test-list registration was not established.
• tests/unittest/_torch/visual_gen/multi_gpu/test_wan_vsa_ulysses.py: Changes the distributed worker rendezvous address for Wan VSA Ulysses. Test-list registration was not established.
• tests/unittest/_torch/visual_gen/test_flux_pipeline.py: Changes the distributed setup rendezvous address for the Flux pipeline test. Test-list registration was not established.

Description

Use 127.0.0.1 for rendezvous in 26 VisualGen test files so the clients use the IPv4 address family checked by the port allocator.

The failure occurs when localhost resolves to both 127.0.0.1 and ::1:

1. An unrelated process already listens on IPv6 port [::1]:P. The allocator probes only IPv4, so it reports port P as free.
2. Rank 0 starts TCPStore. Its dual-stack IPv6 bind conflicts with that listener, so TCPStore falls back to an IPv4 listener on 0.0.0.0:P. Store startup succeeds.
3. TCPStore clients resolve localhost and try ::1:P first. They reach the unrelated process, while rank 0's store is listening on IPv4.
4. That process closes the connection or replies using its own protocol. Clients then retry until timeout or report an invalid ping reply; the value 759714643 decodes to the bytes SSH-.

Using 127.0.0.1 directs clients to the IPv4 store even when an IPv6 listener occupies the same port. An IPv4 bind collision still reaches the existing EADDRINUSE retry path in tests using spawn_with_retry.

The CI failure signatures are consistent with this mechanism; the original CI node's name resolution and port owner have not been confirmed.

Test Coverage

Controlled checks of the two LTX-2 initializer functions reproduced connection-reset and invalid-ping failures before the change; all four cases passed afterward with zero connections to the foreign IPv6 listener. Runtime validation used Gloo with world_size=1; full model parity and the other 24 initializers were not executed.

All 26 files passed Python AST parsing and pre-commit checks.

PR Checklist

• PR description clearly explains what and why.

• PR Follows TRT-LLM CODING GUIDELINES.

• Test cases are provided for new code paths.

• Any new dependencies have been scanned for license and vulnerabilities.

• CODEOWNERS updated if ownership changes.

• Documentation updated as needed.

• Update tava architecture diagram if significant design change.

• Please check this after reviewing the above items as appropriate for this PR.

[luyiyun1021]

/bot run --disable-fail-fast

[coderabbitai]

Walkthrough

Distributed visual generation test setup now assigns 127.0.0.1 to MASTER_ADDR instead of localhost. The change appears in unit tests and an integration test.

Changes

Visual generation distributed tests

Layer / File(s)	Summary
Distributed test master address configuration tests/unittest/_torch/visual_gen/multi_gpu/*, tests/unittest/_torch/visual_gen/test_flux_pipeline.py, tests/integration/defs/examples/visual_gen/test_visual_gen_multi_gpu.py	Distributed test setup now assigns 127.0.0.1 to MASTER_ADDR instead of localhost. Other initialization behavior is unchanged in the supplied summaries.

Priority: ➖ Normal

Estimated code review effort: 1 (Trivial) | ~3 minutes

Change: Bug fix

Suggested reviewers: bowenfu

Merge Risk: 🔵 Low · up to db708

Confirm whether these tests are intentionally local-only or add them to the appropriate test list before relying on CI coverage.

Pre-merge checks · 4 · 1

Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage		Docstring coverage is 19.23% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 26 functions across 26 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.
Title check		The title is concise, specific, and accurately describes the IPv4 loopback change for VisualGen test rendezvous. It follows the repository's ticket and type format.
Description check		The description explains the failure mechanism, the solution, affected files, test coverage, validation limits, and checklist status. It is complete and directly related to the changes.

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[coderabbitai]

Actionable comments posted: 1

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Inline comments:
Review comments at
@tests/integration/defs/examples/visual_gen/test_visual_gen_multi_gpu.py:
- Line 154: Confirm the execution scope of both multi-GPU tests in the VisualGen
test module: add them to the appropriate multi-GPU CI or QA test list if they
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📥 Commits

Reviewing files that changed from the base of the PR and between fced9ff and db708f9.

📒 Files selected for processing (26)

• tests/integration/defs/examples/visual_gen/test_visual_gen_multi_gpu.py
• tests/unittest/_torch/visual_gen/multi_gpu/test_attn2d_attention.py
• tests/unittest/_torch/visual_gen/multi_gpu/test_cosmos3_transformer_parallel.py
• tests/unittest/_torch/visual_gen/multi_gpu/test_flux2_transformer_parallel.py
• tests/unittest/_torch/visual_gen/multi_gpu/test_flux_tp.py
• tests/unittest/_torch/visual_gen/multi_gpu/test_flux_ulysses.py
• tests/unittest/_torch/visual_gen/multi_gpu/test_ltx2_async_ulysses.py
• tests/unittest/_torch/visual_gen/multi_gpu/test_ltx2_parallel_vae.py
• tests/unittest/_torch/visual_gen/multi_gpu/test_ltx2_ulysses.py
• tests/unittest/_torch/visual_gen/multi_gpu/test_parallel_attention.py
• tests/unittest/_torch/visual_gen/multi_gpu/test_parallel_conv.py
• tests/unittest/_torch/visual_gen/multi_gpu/test_parallel_group_norm.py
• tests/unittest/_torch/visual_gen/multi_gpu/test_parallel_vae.py
• tests/unittest/_torch/visual_gen/multi_gpu/test_qwen_image_attention_parallel.py
• tests/unittest/_torch/visual_gen/multi_gpu/test_ring_attention.py
• tests/unittest/_torch/visual_gen/multi_gpu/test_tp_attention.py
• tests/unittest/_torch/visual_gen/multi_gpu/test_ulysses_async.py
• tests/unittest/_torch/visual_gen/multi_gpu/test_ulysses_attention.py
• tests/unittest/_torch/visual_gen/multi_gpu/test_ulysses_sage_attention.py
• tests/unittest/_torch/visual_gen/multi_gpu/test_visual_gen_mapping.py
• tests/unittest/_torch/visual_gen/multi_gpu/test_wan_async_ulysses.py
• tests/unittest/_torch/visual_gen/multi_gpu/test_wan_pipeline_parallel.py
• tests/unittest/_torch/visual_gen/multi_gpu/test_wan_tp.py
• tests/unittest/_torch/visual_gen/multi_gpu/test_wan_transformer_parallel.py
• tests/unittest/_torch/visual_gen/multi_gpu/test_wan_vsa_ulysses.py
• tests/unittest/_torch/visual_gen/test_flux_pipeline.py

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CI Report

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[github-actions]

Automatically added "ci: full pre-merge approved" because this PR has satisfied the required GitHub review approvals. Unresolved review conversations and other required checks remain independent merge requirements.

[luyiyun1021]

/bot run --disable-fail-fast

[tensorrt-cicd]

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PR_Github #77484 [ run ] completed with state SUCCESS. Commit: db708f9
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