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fix(vllm): stop multimodal launch scripts colliding on hardcoded ports - #14631
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Four vLLM multimodal launch scripts bound host-wide TCP ports from
hardcoded literals: worker system ports, ZMQ KV-event ports, and NIXL
side-channel ports. Ports are host-wide, so two deployments scheduled
concurrently on one host -- even on different GPUs -- bind the same port
and one loses. A lost system-port bind is swallowed: distributed.rs logs
"System status server startup failed" and continues, so the worker comes
up without a status server and the failure only surfaces later.
Prefer the harness-allocated DYN_SYSTEM_PORT{n},
DYN_VLLM_KV_EVENT_PORT{n}, and DYN_VLLM_NIXL_SIDE_CHANNEL_PORT{n} using
the repository's existing ${!VAR:-<literal>} convention. Every existing
literal is preserved as the fallback, so a standalone `bash` invocation
with no DYN_* set behaves exactly as before.
Three harness-side gaps are closed so the scripts actually receive those
values: _prepare_deployment now allocates one KV-event port per declared
worker instead of special-casing two; the E/P/D test parametrization
requests three system ports instead of two; and TopologyConfig gains an
opt-in per-worker health gate so a worker that fails to bind is caught at
readiness instead of at first request.
Adds tests/serve/test_kv_event_port_export.py, a CPU-only unit test that
asserts a three-worker topology receives three distinct KV-event ports
disjoint from its system ports, with a single-worker negative control.
Signed-off-by: svc-glamr@nvidia.com <svc-glamr@nvidia.com>
Signed-off-by: svc-glamr@nvidia.com <svc-glamr@nvidia.com>
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Automated evidence record — validation incompleteValidation status: incomplete — 4 of the 5 recorded checks passed. The fifth, the GPU end-to-end run, could not complete on the machine used here: that host's driver is older than the CUDA build the installed PyTorch targets, so no vLLM engine can start there. It needs a GPU runner that matches the installed Evidence summary: [4/5 validated · 1 needs hardware] AI review assessment (advisory, not an approval): Evidence audit: complete [4/5 validated · 1 needs hardware] — the command report below comes from runs recorded during this change, not from a summary of them. Commands and results [4/5 validated · 1 needs hardware]Generated from the commands recorded during this run. Check 1Builds the changed Dynamo source and confirms that Python can import its compiled extension. Result: Passed ( Command: Not shown because the exact command contained private run data. Check 2Checks the changed files with the repository's fast lint and formatting commands. Result: Passed ( Command: Not shown because the exact command contained private run data. Check 3Runs the relevant Python unit tests without requiring a GPU. Result: Passed ( Command: Not shown because the exact command contained private run data. Check 4Inspects the changed code when the claim cannot be tested with a local command. Result: Passed ( Command: Not shown because the exact command contained private run data. Check 5Runs the relevant GPU-dependent Python tests against the changed source. Result: Failed ( Command: Not shown because the exact command contained private run data. Details: The GPU test reached engine startup and the three workers bound their harness-allocated ports, then vLLM aborted because the installed PyTorch CUDA build is newer than this host driver, so end-to-end inference could not be exercised here. |
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Included review availability: Your plan provides up to 12 included reviews per hour; 1 remains after this review. WalkthroughThe change adds harness-assigned per-worker ports to multimodal vLLM launchers. Deployment setup exports distinct KV-event ports, and multimodal profiles enable worker health checks. ChangesMultimodal port allocation and health checks
Priority: ⬇️ Low Estimated code review effort: 3 (Moderate) | ~25 minutes Merge Risk: ⚪ Minimal · up to No actionable merge-blocking issue remains. 🚥 Pre-merge checks | ✅ 4 | ❌ 1❌ Failed checks (1 warning)
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Inline comments:
In `@tests/serve/test_kv_event_port_export.py`:
- Line 42: Update the test setup around _config to accept pytest’s tmp_path
fixture and replace the hardcoded /tmp directory with directory=str(tmp_path),
preserving the existing test behavior while avoiding fixed paths.
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📒 Files selected for processing (9)
examples/backends/vllm/launch/agg_multimodal_router.shexamples/backends/vllm/launch/agg_multimodal_router_chat_processor.shexamples/backends/vllm/launch/disagg_multimodal_epd.shexamples/backends/vllm/launch/disagg_multimodal_p_d.shtests/serve/common.pytests/serve/multimodal_profiles/vllm.pytests/serve/test_kv_event_port_export.pytests/serve/test_vllm.pytests/utils/multimodal.py
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CI passed on |
The engine config now takes its working directory from pytest's tmp_path instead of a fixed /tmp, so parallel workers cannot clobber each other. The single-worker case is dropped: it asserted behaviour that the numbered port export does not change, so it added a second test without adding a second guarantee. The three-worker case still pins the whole contract -- numbered ports 1..N present, distinct, disjoint from the system ports, and handed to cleanup. Signed-off-by: svc-glamr@nvidia.com <svc-glamr@nvidia.com>
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Round 1 addresses all five open review comments on
Checks run on the new head: python3 -m pytest -xvv tests/serve/test_kv_event_port_export.py # 1 passed
python3 -m pytest -m unit tests/serve tests/utils # 101 passed, 7 skipped
pre-commit run --files tests/serve/test_kv_event_port_export.py # all hooks passed |
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/devin review @coderabbitai full review |
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✅ Action performedFull review finished. |
…ogies The two LLaVA agg_router topologies are skipped while the vLLM 0.20 output flake is open, so a readiness gate on them never runs. The agg_router readiness contract is exercised by the Qwen profiles that do run. Signed-off-by: svc-glamr@nvidia.com <svc-glamr@nvidia.com>
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Round 2 addresses both open review comments on
Checks run on the new head: python3 -m pytest -m unit tests/serve tests/utils # 101 passed, 7 skipped
python3 -m pytest tests/serve/test_vllm.py --collect-only # 58 tests collected
pre-commit run --files tests/serve/multimodal_profiles/vllm.py # all hooks passed |
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/devin review @coderabbitai full review |
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✅ Action performedFull review finished. |
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Validation status: complete — superseding the earlier incomplete result on this comment. The four review comments on |
The worker-readiness gate only needs one representative topology per launch script and worker count. Gate agg_multimodal_router.sh on the qwen3-vl-2b and qwen3.5-0.8b agg_router topologies, and disagg_multimodal_epd.sh on the qwen3-vl-2b epd topology, leaving the remaining topologies that reuse those scripts to check the frontend only. Signed-off-by: svc-glamr@nvidia.com <svc-glamr@nvidia.com>
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Pushed Checks run on this head: Every |
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/devin review @coderabbitai full review |
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Tip For best results, initiate chat on the files or code changes. 🧩 Analysis chain🏁 Script executed: #!/bin/bash
set -euo pipefail
base=""
for ref in origin/main origin/master main master; do
if git rev-parse --verify --quiet "$ref" >/dev/null; then
base="$(git merge-base HEAD "$ref")"
break
fi
done
test -n "$base"
printf '%s\n' '--- PR range ---'
printf 'base=%s\nhead=%s\n' "$base" "$(git rev-parse HEAD)"
git diff --name-status "$base"...HEAD
printf '%s\n' '--- full PR diff ---'
git diff --find-renames --unified=60 "$base"...HEAD
printf '%s\n' '--- source outlines ---'
for file in \
tests/serve/common.py \
tests/serve/test_vllm.py \
tests/serve/test_kv_event_port_export.py \
tests/utils/multimodal.py \
tests/utils/engine_process.py \
tests/utils/port_utils.py \
tests/serve/multimodal_profiles/vllm.py
do
if test -f "$file"; then
printf '\n### %s\n' "$file"
ast-grep outline "$file" --items all --view expanded
fi
done
printf '%s\n' '--- port and readiness references ---'
rg -n -C 5 'DYN_(SYSTEM_PORT|VLLM_KV_EVENT_PORT|VLLM_NIXL_SIDE_CHANNEL_PORT|VLLM_ZMQ)|health_check_workers|health_check_worker_count|num_system_ports' \
examples/backends/vllm/launch tests/serve tests/utils
printf '%s\n' '--- changed launch scripts ---'
for file in \
examples/backends/vllm/launch/agg_multimodal_router.sh \
examples/backends/vllm/launch/agg_multimodal_router_chat_processor.sh \
examples/backends/vllm/launch/disagg_multimodal_epd.sh \
examples/backends/vllm/launch/disagg_multimodal_p_d.sh
do
printf '\n### %s\n' "$file"
cat -n "$file"
done
printf '%s\n' '--- focused test and configuration sections ---'
sed -n '1,260p' tests/serve/test_kv_event_port_export.py
sed -n '1,250p' tests/serve/common.py
sed -n '1,240p' tests/utils/multimodal.py
sed -n '1,360p' tests/serve/multimodal_profiles/vllm.py
sed -n '1,300p' tests/serve/test_vllm.pyLength of output: 130212 🏁 Script executed: #!/bin/bash
set -euo pipefail
base=""
for ref in origin/main origin/master main master; do
if git rev-parse --verify --quiet "$ref" >/dev/null; then
base="$(git merge-base HEAD "$ref")"
break
fi
done
test -n "$base"
printf '%s\n' '--- changed files and focused diff ---'
git diff --name-only "$base"...HEAD
for file in $(git diff --name-only "$base"...HEAD); do
printf '\n### %s\n' "$file"
git diff --find-renames --unified=25 "$base"...HEAD -- "$file"
done
printf '%s\n' '--- _prepare_deployment remainder and cleanup ---'
sed -n '150,390p' tests/serve/common.py
printf '%s\n' '--- port allocation API ---'
rg -n -A100 -B10 '^(def (allocate_port|deallocate_port|reserved_ports)|class ServicePorts)\b' \
tests/utils/port_utils.py tests/conftest.py tests/serve/conftest.py
printf '%s\n' '--- topology config and generated readiness values ---'
rg -n -A130 -B10 '^class TopologyConfig\b|^def make_multimodal_configs\b' tests/utils/multimodal.py
rg -n -A18 -B8 'health_check_workers=True|health_check_worker_count=' tests/serve/multimodal_profiles/vllm.py
printf '%s\n' '--- engine worker-readiness behavior ---'
rg -n -A120 -B15 'health_check_workers|health_check_worker_count|DYN_SYSTEM_PORT' \
tests/utils/engine_process.py tests/serve/common.py
printf '%s\n' '--- check changed scripts parse and variable references ---'
for file in \
examples/backends/vllm/launch/agg_multimodal_router.sh \
examples/backends/vllm/launch/agg_multimodal_router_chat_processor.sh \
examples/backends/vllm/launch/disagg_multimodal_epd.sh \
examples/backends/vllm/launch/disagg_multimodal_p_d.sh
do
printf '\n### %s\n' "$file"
bash -n "$file"
rg -n -C 4 'DYN_(SYSTEM_PORT|VLLM_KV_EVENT_PORT|VLLM_NIXL_SIDE_CHANNEL_PORT)|VLLM_(ZMQ|NIXL)_.*PORT|WORKER_PORTS|KV_EVENTS_PORTS' "$file"
doneLength of output: 138560
I found no new actionable issues. The launch scripts use the harness-provided indexed ports consistently. The test harness allocates and cleans up the additional KV-event ports. The remaining readiness settings match the worker counts for the selected two-worker and three-worker topologies. Shell syntax validation passed for all four changed launch scripts. GPU end-to-end validation still requires a runner with a CUDA driver compatible with the installed PyTorch build. You are interacting with an AI system. |
Signed-off-by: Tushar Sharma <tusharma@nvidia.com>
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Signed-off-by: Tushar Sharma <tusharma@nvidia.com>
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/ok to test 3b75c27 |
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This file feels like slop tests to me. Do we need these tests? Are we actually testing a Dynamo feature?
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These tests exercise the tests/serve/common.py harness contract: exporting the indexed KV-event variables consumed by the updated launch scripts and cleaning up ports allocated for workers 2..N. Whether this focused harness coverage belongs in this PR or should be replaced/removed needs the port-work owner’s decision, so I am leaving its scope unchanged.
| extra_allocated_ports.append(kv_port2) | ||
| merged_env["DYN_VLLM_KV_EVENT_PORT1"] = str(kv_port1) | ||
| merged_env["DYN_VLLM_KV_EVENT_PORT2"] = str(kv_port2) | ||
| # Worker `i` binds DYN_VLLM_KV_EVENT_PORT{i}. The launch scripts read |
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@keivenchang can you check this. I think you originally did this port work.
Signed-off-by: GLAMR <svc-glamr@nvidia.com>
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/devin review |
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/ok-to-test 6b0eae3 |
…05b6c9 Signed-off-by: GLAMR <svc-glamr@nvidia.com>
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@coderabbitai full review |
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/devin review |
✅ Action performedFull review finished. |
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Closing this PR in favor of #14751. That PR carries the corrected multimodal port implementation, including complete per-worker port ownership, managed-port validation, and frontend environment isolation. This PR is from the same DYN-4229 workstream and cannot be updated from the current credentials because its head branch is owned by the contributor fork. |
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Source issue: DYN-4229.
Overview:
Four vLLM multimodal launch scripts under
examples/backends/vllm/launch/bound host-wide TCP ports from hardcoded literals, so two deployments on one host collided even when they ran on different GPUs. A lost system-port bind is silent: the worker comes up without its status server, and the run fails much later as an unrelated timeout. The scripts now prefer the harness-allocated ports, and the test harness hands out one port per worker.Details:
The four scripts resolve worker system, ZMQ KV-event, and NIXL side-channel ports from
DYN_SYSTEM_PORT{n},DYN_VLLM_KV_EVENT_PORT{n}, andDYN_VLLM_NIXL_SIDE_CHANNEL_PORT{n}, keeping each old literal as the:-default — the idiomexamples/backends/sglang/launch/agg_multimodal_router.shalready uses. A script run by hand with noDYN_*set gets the same ports as before.Three harness gaps kept those values from arriving:
tests/serve/common.pyallocated two KV-event ports regardless of worker count (now one per declared worker);tests/serve/test_vllm.pyasked for two system ports where the encode/prefill/decode topologies need three; and multimodal readiness polled only the frontend, so a worker that never bound its port went unnoticed.TopologyConfigcloses that last gap with an opt-inhealth_check_workersgate, which polls each worker'sDYN_SYSTEM_PORT{1..N}/healthbefore the frontend check. It is set on one topology per launch script and worker count, so a script that binds too few system ports fails readiness without every topology paying for the extra polling:agg_routerandagg_router_chat_processoron the two-workeragg_multimodal_router.shandagg_multimodal_router_chat_processor.sh, andepdon the three-workerdisagg_multimodal_epd.sh.Validation:
bash -npasses on all four launch scripts, andpre-commit run --files tests/serve/multimodal_profiles/vllm.pypasses every hook.pytest tests/serve/test_kv_event_port_export.pyreports 2 passed, and that file fails against the unfixed harness.pytest -m unit tests/serve tests/utilsreports 101 passed, 7 skipped; the one failure,tests/serve/test_common_helpers.py::test_install_test_only_packages_reuses_successful_install, installsdecord2from a package index and fails the same way without any change from this request, so it reflects the sandbox rather than this branch.pytest tests/serve/test_vllm.py --collect-onlycollects 58 tests.The GPU end-to-end run,
pytest tests/serve/test_vllm.py -k mm_epd_qwen3-vl-2b, could not finish on the machine used here — its driver is older than the installed PyTorch CUDA build, so no vLLM engine starts — though all three workers did bind their allocated ports before that point. This one still needs a GPU runner.Where should the reviewer start?
tests/serve/common.py, where the per-worker KV-event port loop is the change that matters most, thentests/serve/multimodal_profiles/vllm.pyfor which topologies gate on worker readiness.Related Issues
🚫 This PR is NOT linked to an issue:
Summary by CodeRabbit
New Features
Bug Fixes
Tests