[https://nvbugs/5670793][fix] Solve trtllm-serve launch_disaggregated issue

[xxi-nv]

Description

This is a cherry-pick from https://github.com/NVIDIA/TensorRT-LLM/pull/9324 to fix the similar issue on main.

Test Coverage

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Summary by CodeRabbit

Improvements

• Enhanced the internal communication mechanism for serving processes to improve system stability and efficiency.
• Optimized address allocation strategy for inter-process communication to better manage system resources.
• Streamlined process initialization workflow and updated environment configuration accordingly.
• Reduced overall resource overhead in the serving component while maintaining functionality.

_{✏️ Tip: You can customize this high-level summary in your review settings.}

[xxi-nv]

/bot run

[coderabbitai[bot]]

📝 Walkthrough

Walkthrough

Refactors inter-process communication mechanism from TCP ports to IPC addresses. Introduces find_free_ipc_addr() utility function that generates UUID-based IPC addresses in the system temp directory, replacing TCP port allocation used by the disaggregated leader spawning process.

Changes

Cohort / File(s)	Summary
IPC Address Utility tensorrt_llm/llmapi/mpi_session.py	New function find_free_ipc_addr() -> str generates UUID-based IPC address string in system temp directory, returns format ipc://<tempdir>/rpc_<uuid>
Server Proxy Launch Integration tensorrt_llm/commands/serve.py	Replaces find_free_port import with find_free_ipc_addr; updates _launch_disaggregated_leader to use IPC address instead of TCP port; sets TLLM_SPAWN_PROXY_PROCESS_IPC_ADDR environment variable to IPC address string instead of tcp://127.0.0.1:<port> format

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

• The changes are localized and follow a straightforward substitution pattern (TCP port → IPC address)
• New function is concise with clear responsibility
• Environment variable wiring logic is consistent
• Consider verifying:
  • IPC address format compatibility across intended platforms
  • Proper cleanup/lifecycle management of temp files used by IPC addresses
  • No other code paths expect the old tcp:// format for this environment variable

Pre-merge checks and finishing touches

❌ Failed checks (1 warning, 1 inconclusive)

Check name	Status	Explanation	Resolution
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.
Description check	❓ Inconclusive	The PR description lacks specific details about what was fixed, why it was necessary, and what tests validate the changes.	Add a substantive explanation of the issue being fixed and list specific tests that validate the changes in the Test Coverage section.

✅ Passed checks (1 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title directly addresses the main change: fixing a trtllm-serve launch_disaggregated issue by replacing TCP port allocation with IPC address allocation.

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[tensorrt-cicd]

PR_Github #25264 [ run ] triggered by Bot. Commit: ee5a9b8

[tensorrt-cicd]

PR_Github #25264 [ run ] completed with state SUCCESS. Commit: ee5a9b8 /LLM/main/L0_MergeRequest_PR pipeline #19111 completed with status: 'FAILURE'

[longlee0622]

/bot run --disable-fail-fast

[tensorrt-cicd]

PR_Github #25296 [ run ] triggered by Bot. Commit: ee5a9b8

[JunyiXu-nv]

L0 is failing on deepgemm clone, should be fixed by: https://github.com/NVIDIA/TensorRT-LLM/pull/9349

Need rebase/rerun after that PR...

[tensorrt-cicd]

PR_Github #25296 [ run ] completed with state SUCCESS. Commit: ee5a9b8 /LLM/main/L0_MergeRequest_PR pipeline #19137 completed with status: 'FAILURE'

[JunyiXu-nv]

/bot run

[tensorrt-cicd]

PR_Github #25640 [ run ] triggered by Bot. Commit: 5703c1f

[tensorrt-cicd]

PR_Github #25640 [ run ] completed with state FAILURE. Commit: 5703c1f LLM/main/L0_MergeRequest_PR #19427 (Blue Ocean) completed with status: ABORTED

[xxi-nv]

/bot run

[tensorrt-cicd]

PR_Github #25815 [ run ] triggered by Bot. Commit: 5703c1f

[tensorrt-cicd]

PR_Github #25815 [ run ] completed with state FAILURE. Commit: 5703c1f /LLM/main/L0_MergeRequest_PR pipeline #19580 completed with status: 'FAILURE'

[longlee0622]

/bot run

[xxi-nv]

/bot run

[xxi-nv]

/bot run

[tensorrt-cicd]

PR_Github #25899 [ run ] triggered by Bot. Commit: 5703c1f

[xxi-nv]

/bot run

[tensorrt-cicd]

PR_Github #25918 [ run ] triggered by Bot. Commit: 5703c1f

[tensorrt-cicd]

PR_Github #25899 [ run ] completed with state ABORTED. Commit: 5703c1f LLM/main/L0_MergeRequest_PR #19640 (Blue Ocean) completed with status: ABORTED

[tensorrt-cicd]

PR_Github #25918 [ run ] completed with state SUCCESS. Commit: 5703c1f /LLM/main/L0_MergeRequest_PR pipeline #19651 completed with status: 'SUCCESS' Pipeline passed with automatic retried tests. Check the rerun report for details.