[iyastreb]

What?

Execute progress loop in dedicated worker threads, even if no requests come

Why?

To guarantee dedicated worker destroys endpoints.
We can change implementation in the future, once dedicated worker is fully controlled from it's thread.
For now this is a viable option to fix resource leak

Summary by CodeRabbit

• Improvements
  • UCX background processing continues during idle periods instead of waiting indefinitely for a task, helping communication progress.
  • Available queued tasks are still handled, and request completion processing remains unchanged.
  • Queue waits can now have a timeout: they return the oldest available item or indicate that the queue is empty when the timeout expires.

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[iyastreb]

/build

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📝 Walkthrough

Walkthrough

The blocking queue adds a stop-aware timed pop overload. When no requests are outstanding, the UCX dedicated thread progresses its worker and waits up to one second for a queued task.

Changes

Timed queue waits and UCX worker progress

Layer / File(s)	Summary
Timed blocking queue pop src/utils/common/blocking_queue.h, test/gtest/blocking_queue_test.cpp	The queue adds a timed pop that returns the oldest item if available or nullptr if the queue is empty. Tests cover timeout, stop requests, and item arrival. The test removes <vector> although the unchanged MPMC test still uses std::vector.
UCX idle worker progress src/plugins/ucx/ucx_thread_pool_engine.cpp	When no requests are outstanding, the dedicated thread calls progressLoop() and waits up to one second for a task. It runs the task when the returned pointer is non-null.

Priority: ➖ Normal

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix

Merge Risk: 🟡 Moderate · up to 7dc89

A queued UCX operation can wait indefinitely if worker progress never goes idle, leaving its caller blocked. Resolve this task-versus-progress ordering risk before merging.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 6 functions across 3 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description check	✅ Passed	The description includes the required What and Why sections. It clearly states that dedicated worker threads must continue progress when no requests arrive and links the change to endpoint destruction…
Title check	✅ Passed	The title clearly identifies the UCX plugin and the main change: adding idle progress to the thread pool. It is concise and related to the pull request.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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🔵 Trivial · Restore the direct <vector> include. · blocking_queue_test.cpp:24

test/gtest/blocking_queue_test.cpp:24
📐 Maintainability & Code Quality | 🔵 Trivial | ⚡ Quick win

Restore the direct <vector> include.

The MPMC test still uses std::vector at lines 122 and 124. Without a direct include, the test depends on a transitive include that can change. Restore <vector> in this file.

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Review comment at @test/gtest/blocking_queue_test.cpp at line 24:
Restore the direct vector header include in the blocking queue test file so its
uses of std::vector do not rely on transitive includes.

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Outside diff comments:
Review comments at @test/gtest/blocking_queue_test.cpp:
- Line 24: Restore the direct vector header include in the blocking queue test
file so its uses of std::vector do not rely on transitive includes.

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[iyastreb]

/build

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Actionable comments posted: 1

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Inline comments:
Review comments at @src/plugins/ucx/ucx_thread_pool_engine.cpp:
- Line 310: Update the empty-requests branch in the task loop to check queue_
between UCX progress calls, so queued tasks can run even while progress remains
nonzero. Use tryPop before and during progress, and retain the timed pop when no
task is available; locate the branch by getWorkers().front()->progressLoop().

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[svc-nixl]

🤖 CI Triage Agent — nixl-ci-dl-gpu-ep · commit e6d233e0

TL;DR: The build itself compiled fine; the job failed in "Allocate DL EP Environment" because salloc on the gb200nvl72_cx8 partition of dlcluster sat queued for the full --immediate=3600 window and gave up with "Unable to allocate resources: Connection timed out" — a cluster capacity/queue issue, not a defect in the PR. Re-run once nodes free up, and fix the allocation helper to cancel/retry the orphaned pending job.

Full analysis

Summary: Stage Allocate DL EP Environment (node 162) failed after ~60 min: salloc: error: Unable to allocate resources: Connection timed out for job nixl-ci-dl-gpu-ep-1538.

Root cause: No code or build failure. The preceding stage "Compiling NIXL EP Docker Image for DL" (node 147) completed successfully — UCX and NIXL built, all 319 ninja targets linked, nixlbench built, and the image nixl-ci-dl-gpu-ep-test:1538 was tagged and pushed at 06:25:30. The pipeline then ran:

salloc -N 1 -p gb200nvl72_cx8 --job-name=nixl-ci-dl-gpu-ep-1538 --immediate=3600 --time=02:00:00 --no-shell --account=blackwell

issued at 06:25:33. The only large gap in the log (06:25:33 → 07:25:42, ~60 min) is inside salloc itself, and slurm explains it in its own words rather than going silent:

salloc: Pending job allocation 2402828
salloc: job 2402828 queued and waiting for resources
salloc: error: Unable to allocate resources: Connection timed out

That is --immediate=3600 expiring: slurm could not satisfy a 1-node exclusive GB200 allocation on gb200nvl72_cx8 within the hour. This is a scheduler/capacity condition, not a hang in nixl code — the wait is an explicit, intentional block, and the failing command is slurm's, not the test's.

A secondary problem is visible in the cleanup stage: slurm.stopAllForBuild logged WARNING: No job ID files found in /mnt/pvc/nixl-ci-dl-gpu-ep/. Because the allocation never succeeded, jobIdFile (job_id_ep_1538.txt) was never written, so pending job 2402828 was not scancel'd by the pipeline and may still be sitting in the queue on dlcluster, consuming priority against subsequent builds of this job.

Implicated commit: none — the PR under test (e6d233e, iyastreb/tp-6-idle-progress) built cleanly. Closest related CI change is 1f87bd7 "CI: exclude misconfigured Vera Rubin nodes from nixl-ci-gpu-vr" (NirWolfer), which shows partition node-availability problems have recently been handled by excluding nodes, but it does not touch this pipeline's partition.

File: CI pipeline definition for nixl-ci-dl-gpu-ep — the slurm.allocation call in the shared swx-jenkins-lib (args logged verbatim at build log 06:25:33: partition:gb200nvl72_cx8, immediateTimeout:3600, jobIdFile:/mnt/pvc/nixl-ci-dl-gpu-ep/job_id_ep_1538.txt).

Suggested fix:

1. Retry the build — nothing in the PR caused this. Verify partition health first with sinfo -p gb200nvl72_cx8 / squeue -p gb200nvl72_cx8 on dlcluster; a single long-running exclusive job on the only GB200 node will reproduce this indefinitely.
2. Have an admin confirm pending job 2402828 is gone and scancel it if not.
3. Harden slurm.allocation in swx-jenkins-lib: parse the Pending job allocation <id> line and write it to jobIdFile before waiting, so the pipeline_stop stage can cancel an allocation that timed out rather than logging "No job ID files found" and leaving it queued.
4. Consider dropping --immediate=3600 to a few minutes and adding an outer retry, so a saturated partition fails fast and visibly instead of burning an hour of Jenkins executor time per attempt.

Related: none found — searches for the salloc error and for this pipeline returned only unrelated open PRs.

[svc-nixl]

🤖 CI Triage Agent — nixl-ci-dl-gpu-ep · commit e6d233e0

TL;DR: The build failed in the "Allocate DL EP Environment" stage — salloc on dlcluster.nvidia.com was rejected with a MUNGE authentication error (Munge decode failed: Unauthorized credential for client UID=148069 GID=30), which is a slurm/munge infrastructure problem on the DL cluster, not a defect in PR #2354. Re-run the job after the cluster admins fix munged (key mismatch / stale daemon) on the submit host dlfw-infra-vm-hpc-runner4.nvidia.com.

Full analysis

Summary: Stage Allocate DL EP Environment (node 170) of nixl-ci-dl-gpu-ep #1544 failed: slurm job allocation 2406988 on partition gb200nvl72_cx8 was aborted with salloc: error: Job submit/allocate failed: Protocol authentication error.

Root cause: MUNGE credential authentication between the slurm client on the submitting host and the slurm controller is broken. The log shows the allocation was accepted and queued (salloc: Pending job allocation 2406988, job 2406988 queued and waiting for resources) and then immediately:

salloc: error: Munge decode failed: Unauthorized credential for client UID=148069 GID=30
salloc: auth/munge: _print_cred: ENCODED: Thu Jan 01 00:00:00 1970
salloc: auth/munge: _print_cred: DECODED: Thu Jan 01 00:00:00 1970
salloc: error: slurm_unpack_received_msg: [dlfw-infra-vm-hpc-runner4.nvidia.com:37568] auth_g_verify: SRUN_STEP_MISSING has authentication error
salloc: error: _accept_msg_connection[10.127.18.45:37568]: Protocol authentication error

The zeroed ENCODED/DECODED timestamps plus "Unauthorized credential" are the classic signature of a munged problem on the host receiving the callback (dlfw-infra-vm-hpc-runner4.nvidia.com): either a munge.key mismatch with the controller, munged not running / recently restarted with a different key, or the UID/GID of the svc-nixl service account not being authorized in munged's allowed-UID set. Nothing in the build itself is implicated — all preceding stages passed, including the full NIXL+nixlbench compile and the nixl-ci-dl-gpu-ep-test:1544 image push (stage 155, "Compiling NIXL EP Docker Image for DL", succeeded in ~28 min).

This is also not a wall-clock kill. The 17.5-minute gap between 12:03:44 (ssh/salloc issued) and 12:21:22 (output flushed) is simply the --immediate=3600 queue wait before the credential check failed; the stage ended on an explicit slurm error, not SIGTERM or a timeout.

Secondary, non-fatal observation: the teardown stage logged WARNING: No job ID files found in /mnt/pvc/nixl-ci-dl-gpu-ep/, so job 2406988 was never recorded in job_id_ep_1544.txt and slurm.stopAllForBuild could not cancel it. If the allocation ever materialized it may be orphaned on the cluster — worth checking with scancel 2406988.

Implicated commit: unknown — no commit in the repo caused this; the failing operation is slurm.allocation from the external swx-jenkins-lib, and commit e6d233e (branch iyastreb/tp-6-idle-progress, PR #2354) never got to run any test code.

File: not a repo file — failure is in the Jenkins slurm.allocation step invoked from the Allocate DL EP Environment stage (.ci/jenkins/pipeline, library swx-jenkins-lib); the error originates on dlcluster.nvidia.com / dlfw-infra-vm-hpc-runner4.nvidia.com.

Suggested fix:

1. Escalate to the DL cluster admins: verify munged is running on dlfw-infra-vm-hpc-runner4.nvidia.com and that its /etc/munge/munge.key is byte-identical to the slurm controller's; restart munged then slurmd/slurmctld as needed. Also confirm UID 148069 (svc-nixl) is permitted by munged's UID/GID restriction list — the error names GID=30, which looks like the account is not in the expected group.
2. Once munge is healthy, simply re-trigger build Query: NIXL over RDMA Network using Mellanox #1544 / re-run CI on PR [6/N] PLUGINS/UCX: Threadpool idle progress #2354 — no code change is required.
3. Check for and cancel any orphaned allocation: scancel 2406988.
4. Hardening (optional, in the pipeline): write the job ID file before the allocation can fail, or have slurm.allocation retry on Protocol authentication error / Munge decode failed, so a transient controller-auth blip doesn't red-flag an otherwise-good PR. Right now a munge hiccup is indistinguishable from a genuine test failure to anyone reading the build status.

Related: PR #2354 ([6/N] PLUGINS/UCX: Threadpool idle progress) — the triggering PR, but not the cause. No existing issue tracks this munge/slurm auth failure; consider filing one against CI infra so repeat occurrences on gb200nvl72_cx8 are tracked.

[iyastreb]

/build

[svc-nixl]

🤖 CI Triage Agent — nixl-ci-dl-gpu-ep · commit 7dc89cb2

TL;DR: The build never ran any tests — the salloc on the DL cluster's gb200nvl72_cx8 partition sat queued for the full --immediate=3600 window (14:59:30 → 15:59:38) and gave up with "Unable to allocate resources: Connection timed out". This is a scheduler capacity/queueing failure, made worse by the job implicitly requesting a whole exclusive GB200 node, not a defect in PR #2354.

Full analysis

Summary: Stage "Allocate DL EP Environment" failed after ~60 min when slurm job 2409780 could not be allocated on partition gb200nvl72_cx8.

Root cause: The earlier stages all succeeded — "Compiling NIXL EP Docker Image for DL" completed and pushed nixl-ci-dl-gpu-ep-test:1550 at 14:59:20. The pipeline then called slurm.allocation with immediateTimeout:3600:

salloc -N 1 -p gb200nvl72_cx8 --job-name=nixl-ci-dl-gpu-ep-1550 --immediate=3600 --time=02:00:00 --no-shell --account=blackwell
salloc: lua: Setting job to exclusive mode as no gpu count was specified
salloc: Pending job allocation 2409780
salloc: job 2409780 queued and waiting for resources
salloc: error: Unable to allocate resources: Connection timed out

The only gap in the log is exactly the 60 min of --immediate=3600 wait, which is the documented behaviour of that flag, not a hang — the job stayed PENDING for the whole window and slurm then aborted it. Note the lua job_submit plugin line: because no GPU count is requested, the job is promoted to exclusive whole-node on a gb200nvl72_cx8 node, which dramatically narrows the set of satisfiable nodes and lengthens queue time. The commit under test (7dc89cb, iyastreb/tp-6-idle-progress) is not implicated — no NIXL code was executed.

Implicated commit: none for the code under test. The closest related CI change is [REDACTED:Hex High Entropy String] (NirWolfer, "CI: request 2 GPUs instead of a whole node for nixl-ci-gpu-vr") — that same whole-node-exclusive problem is still present in the DL EP job's salloc arguments.

File: the slurm.allocation call site for nixl-ci-dl-gpu-ep (argument set logged verbatim: partition:gb200nvl72_cx8, nodes:1, jobTimeout:02:00:00, immediateTimeout:3600, extraArgs:[--account=blackwell]) — in the Jenkins pipeline definition under .ci/jenkins/pipeline/ for this job.

Suggested fix:

1. Add an explicit GPU request (e.g. --gres=gpu:N / --gpus=N via extraArgs) so the lua plugin stops forcing exclusive whole-node mode — the same change already applied to nixl-ci-gpu-vr in [REDACTED:Hex High Entropy String]. This is the highest-value fix; a shared-node request will schedule far sooner on a busy GB200 NVL72 partition.
2. Make the allocation failure retry/report distinctly instead of failing the PR: treat "Unable to allocate resources" as an infra retry (a couple of attempts, or re-queue) rather than surfacing as a red PR check, since it carries no signal about the code.
3. Re-run build obj plugin: introduce registry for vendor backends #1550 — nothing about the PR was actually validated.

Do not raise jobTimeout; the 2 h job limit was never reached. Raising immediateTimeout alone would only extend the wait without addressing why the request can't be satisfied.

Related: PR #2354 (the PR under test — unaffected); CI commit [REDACTED:Hex High Entropy String] applies the equivalent GPU-count fix to another pipeline.

🛡️ This comment had 1 potential secret(s) redacted (Hex High Entropy String). See request_id 83417152-851d-4920-84e6-7ae9f1d9c94d in the triage console for the audit trail.

[svc-nixl]

🤖 CI Triage Agent — nixl-ci-dl-gpu-ep · commit 7dc89cb2

TL;DR: The build never ran any tests — the Allocate DL EP Environment stage asked slurm for an exclusive whole GB200 node on gb200nvl72_cx8, sat queued for the full --immediate=3600 hour, and salloc gave up with "Unable to allocate resources: Connection timed out". This is partition capacity/scheduling, not a defect in PR #2354; fix by requesting a GPU count instead of implicitly taking a whole exclusive node (and/or retrying the allocation).

Full analysis

Summary: Stage 164 "Allocate DL EP Environment" failed after 3610 s when salloc could not obtain a node on the gb200nvl72_cx8 partition; the parallel branch build_helper_dl_ep/aarch64/1 then aborted the pipeline with exit code 1.

Root cause: Resource starvation at the scheduler, not a code or hang failure:

• Everything PR-related succeeded. "Compiling NIXL EP Docker Image for DL" passed (1414 s): UCX installed, meson configured, all 316 ninja targets built and installed, nixlbench built, and the image nixl-ci-dl-gpu-ep-test:1552 was tagged and pushed successfully.
• The allocation stage issued exactly one command at 16:27:09:
  salloc -N 1 -p gb200nvl72_cx8 --job-name=nixl-ci-dl-gpu-ep-1552 --immediate=3600 --time=02:00:00 --no-shell --account=blackwell
• slurm replied Pending job allocation 2411207 / job 2411207 queued and waiting for resources, and at 17:27:18 — precisely 3600 s later — salloc: error: Unable to allocate resources: Connection timed out. The one-hour gap is the --immediate=3600 deadline elapsing while the job sat in the queue; it is not a hung process, because the only thing running was slurm's queue wait, and the failure time matches the configured deadline to the second.
• A contributing factor is visible in the slurm job submit plugin output: salloc: lua: Setting job to exclusive mode as no gpu count was specified. Because no --gpus/--gres is passed, the job is promoted to an exclusive whole-node reservation on a GB200 NVL72 partition, which is far harder to schedule than a partial-node request and makes this an hour-long queue wait rather than a quick grab.
• Cleanup also shows the allocation never materialized: pipeline_stop reported WARNING: No job ID files found in /mnt/pvc/nixl-ci-dl-gpu-ep/, i.e. no job ID was ever written to job_id_ep_1552.txt.

Implicated commit: None in the PR under test — commit 7dc89cb (branch iyastreb/tp-6-idle-progress, PR #2354) is not implicated; it built cleanly. The relevant CI config is the slurm.allocation call for this job, whose closest precedent change is [REDACTED:Hex High Entropy String] "CI: request 2 GPUs instead of a whole node for nixl-ci-gpu-vr" by NirWolfer.

File: Jenkins job definition for nixl-ci-dl-gpu-ep — the slurm.allocation arguments [partition: gb200nvl72_cx8, nodes: 1, immediateTimeout: 3600, extraArgs: [--account=blackwell]] (build log stage 164, line 2). The pipeline YAML was not retrievable at any of the paths tried under .ci/jenkins/pipeline/, so locate it by the job name.

Suggested fix:

1. Pass an explicit GPU count (e.g. --gpus-per-node=4 or whatever the EP test actually needs) in extraArgs so the submit-plugin lua no longer promotes the job to exclusive whole-node mode. This is exactly the change already applied to nixl-ci-gpu-vr in [REDACTED:Hex High Entropy String] and is the highest-value fix.
2. Re-run the build — with a transient queue backlog this will likely pass as-is.
3. Make the allocation resilient rather than fatal: wrap the salloc step in a retry, or have the branch mark the build UNSTABLE/aborted (not FAILURE) when the failure is Unable to allocate resources, so a busy partition does not look like a PR regression to contributors.
4. Do not simply raise immediateTimeout above 3600 — the job was never making progress, it was queued; a longer deadline just lengthens the stall.

Related: PR #2354 (the PR under test, not the cause); [REDACTED:Hex High Entropy String] "CI: request 2 GPUs instead of a whole node for nixl-ci-gpu-vr" (#2352) and 1f87bd7 "CI: exclude misconfigured Vera Rubin nodes" (#2339) are prior fixes for the same class of allocation problem on a different partition.

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[svc-nixl]

🤖 CI Triage Agent — nixl-ci-dl-gpu-ep · commit 7dc89cb2

TL;DR: The build never ran any tests — it failed because the Slurm allocation on dlcluster's gb200nvl72_cx8 partition was never granted within the 1-hour --immediate window, so salloc gave up with "Unable to allocate resources: Connection timed out". This is a cluster-capacity/scheduling issue, aggravated by the job requesting a whole exclusive GB200 node; request a specific GPU count instead (as was already done for nixl-ci-gpu-vr in #2352) and/or retry the allocation.

Full analysis

Summary: Stage "Allocate DL EP Environment" (node 164) failed after ~60 min; salloc on partition gb200nvl72_cx8 could not obtain resources and exited with salloc: error: Unable to allocate resources: Connection timed out.

Root cause: No code defect and no hang in the build. The parallel branch "Compiling NIXL EP Docker Image for DL" (node 149) completed successfully at 18:35 — UCX, nixl 1.5.0, nixlbench all built, image nixl-ci-dl-gpu-ep-test:1555 pushed. The sibling branch requested a node via:

salloc -N 1 -p gb200nvl72_cx8 --job-name=nixl-ci-dl-gpu-ep-1555 --immediate=3600 --time=02:00:00 --no-shell --account=blackwell

Slurm accepted it as pending allocation 2413227 (salloc: job 2413227 queued and waiting for resources) and then timed out. The ~60-minute gap between the ssh at 18:36:23 and the next output at 19:36:31 is exactly the --immediate=3600 window elapsing — this is the allocation waiting by design, not a silent hang, so the "largest gap" here is expected rather than evidence of a stuck process. The partition simply had no free node for the whole hour.

Two contributing details from the log worth noting:

• salloc: lua: Setting job to exclusive mode as no gpu count was specified — because no --gpus/--gres is passed, a site Lua plugin promotes the request to an exclusive whole-node allocation. On a contended GB200 NVL72 partition, a whole-node exclusive request is far harder to schedule than a 2-GPU slice, which makes this timeout much more likely.
• limit: stacksize: Can't set limit is benign shell noise on the head node, unrelated to the failure.

Implicated commit: None — commit 7dc89cb (PR #2354, iyastreb/tp-6-idle-progress) is not implicated; the failure occurs before any NIXL code is exercised. The closest relevant CI change is [REDACTED:Hex High Entropy String] (NirWolfer, "CI: request 2 GPUs instead of a whole node for nixl-ci-gpu-vr", #2352), which applied the analogous fix to a different pipeline but not to this one.

File: The slurm.allocation call for this job — partition:gb200nvl72_cx8, nodes:1, jobTimeout:02:00:00, immediateTimeout:3600, extraArgs:[--account=blackwell] — in the nixl-ci-dl-gpu-ep pipeline definition under .ci/jenkins/ (the specific pipeline YAML was not readable from the repo at this path; the exact arguments are echoed verbatim in the stage-164 log).

Suggested fix:

1. Re-run the build — this is a transient capacity failure and PR [6/N] PLUGINS/UCX: Threadpool idle progress #2354 has not actually been tested yet.
2. Pass an explicit GPU count (e.g. --gpus-per-node=2 or the appropriate --gres) in extraArgs for nixl-ci-dl-gpu-ep, mirroring what CI: request 2 GPUs instead of a whole node for nixl-ci-gpu-vr #2352 did for nixl-ci-gpu-vr. This stops the site Lua plugin from promoting the request to exclusive whole-node and makes it schedulable alongside other jobs.
3. Make the allocation step retry (or fail as UNSTABLE/skipped rather than FAILURE) when salloc returns "Unable to allocate resources", so queue contention on a shared research cluster doesn't show up as a red PR check. A 3600 s --immediate that expires is a queueing signal, not a test result.
4. If exclusive whole-node really is required for the EP test, confirm with the cluster owners that the blackwell account has reserved capacity on gb200nvl72_cx8; allocation 2413227 is the reference an admin can use to see what was occupying the partition during the window.

Related: PR #2354 (the PR under test, not the cause); PR #2352 / commit [REDACTED:Hex High Entropy String] — precedent for replacing a whole-node request with an explicit GPU count in a NIXL Jenkins pipeline.

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[svc-nixl]

🤖 CI Triage Agent — nixl-ci-dl-gpu-ep · commit 7dc89cb2

TL;DR: The build failed in the "Allocate DL EP Environment" stage because salloc on dlcluster.nvidia.com could not get a node in partition gb200nvl72_cx8 within the 1-hour --immediate=3600 window — a cluster capacity/queueing problem, not a defect in PR #2354.

Full analysis

Summary: Stage "Allocate DL EP Environment" (node 164) failed after 3610s with salloc: error: Unable to allocate resources: Connection timed out; the NIXL EP Docker image build stage before it succeeded.

Root cause: Pure infrastructure resource starvation, on two fronts, both visible in the log:

1. Slurm allocation 2420544 (job name nixl-ci-dl-gpu-ep-1562, partition gb200nvl72_cx8, --account=blackwell, -N 1, exclusive) was accepted at 06:20:27 and stayed queued and waiting for resources for the full --immediate=3600 second budget, then was rejected at 07:20:36. The 60-minute gap between consecutive log lines is not a hang in a NIXL component — it is salloc itself blocking by design on a pending allocation, and the terminating message is slurm's immediate-timeout expiry. Note the Lua job submit plugin forced exclusive mode (Setting job to exclusive mode as no gpu count was specified), so the job demanded a whole GB200 node, which makes it much harder to schedule than a GPU-count-scoped request.
2. The same build then could not even get its teardown pod scheduled: repeated exceeded quota: resourcequota-nbu-swx-nixl, requested: cpu=8500m, used: cpu=236800m, limited: cpu=240 — the Jenkins namespace was at 98.7% of its CPU quota, confirming the CI fleet was saturated at that time.

Nothing in the compile stage failed: the full meson/ninja build of 316 targets, the nixlbench build, and the image push to artifactory all completed successfully, so the branch's code (iyastreb/tp-6-idle-progress) is not implicated.

Implicated commit: none — commit [REDACTED:Hex High Entropy String] built cleanly; the failure is in CI resource provisioning, not in the change.

File: Jenkins pipeline slurm allocation step — slurm.allocation(partition: gb200nvl72_cx8, immediateTimeout: 3600, nodes: 1, extraArgs: [--account=blackwell]) in the nixl-ci-dl-gpu-ep Jenkinsfile (stage "Allocate DL EP Environment")

Suggested fix: Retry the build — this is a transient capacity failure with no code signal. To reduce recurrence:

• Pass an explicit --gpus-per-node / --gres=gpu:N to the salloc call so the submit Lua plugin stops promoting the job to --exclusive; requesting a GPU slice instead of a whole GB200 node will schedule far sooner on a busy gb200nvl72_cx8 partition.
• Make the allocation stage retry-and-requeue rather than hard-fail on immediate-timeout, or drop --immediate in favor of a bounded pipeline-level timeout with a retry wrapper, so an hour of queueing doesn't burn the build.
• Separately, raise resourcequota-nbu-swx-nixl (currently cpu=240, observed 236.8 in use) or cap concurrent nixl-ci-dl-gpu-ep builds — the quota ceiling was blocking even the lightweight cleanup pods, which amplified a queue wait into a full pipeline failure.

Related: PR #2354 ([6/N] PLUGINS/UCX: Threadpool idle progress) is the triggering PR but is not the cause; no existing issue tracks this allocation timeout.

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