dockerd likely remains stuck in a socket churn loop. A diagnosis report and patch proposal were created locally.
Published session
Prompt
## Plan Pass
You are planning a fixer patch before any edits happen.
Read the evidence bundle at `./evidence.json`. The prepared workspace is `./workspace` and it was acquired via `debian-source`. The original pre-edit snapshot is available at `./source` if you need to inspect it. For interpreter processes, plan from the script/application entrypoint evidence first and include the runtime only as a second investigation target unless the evidence proves a runtime bug.
Upstream-style expectation: before planning or editing, check for contribution/style docs (`CONTRIBUTING`, `HACKING`, `README-hacking`, `README.md`, `docs/`, `dev-docs/`) and scan the touched subsystem for local helpers. If the project has wrappers for file IO, path-relative IO, process spawning, memory allocation, logging, locking, or platform compatibility, prefer those wrappers over generic libc/std APIs. Do not invent a reproducer or user-visible failure that is not in the evidence bundle; if the evidence is profiler-only or indirect, describe it as a targeted mitigation or stop with a diagnosis instead of presenting a speculative patch as a confirmed bug fix. In the plan and final validation, name any such helper, convention, or evidence limit you found, or say that no relevant local helper was found. Treat this as a `docker.io` upstream patch, not just a Debian-local workaround. Inspect the relevant code, nearby callers, project contribution docs, and local helper/compat APIs, but do not edit files in this pass.
Return a short markdown plan with these exact sections:
## Problem
## Evidence Confidence
## Proposed Subject
## Patch Plan
## Risks
## Validation
Classify `## Evidence Confidence` as exactly one of `reproduced`, `observed`, or `inferred`. Use `inferred` only for a no-patch diagnosis/report plan unless you can name the extra evidence you will collect before editing; inferred source patches are blocked by Fixer because they are not pull-request-ready. For `observed` source-patch plans, plan to say in the final `## Issue Connection` that the failure was observed by Fixer and not independently reproduced. The plan must explain how the proposed code change addresses the observed issue evidence, call out any prior Fixer patch that should be improved or replaced, reject awkward control flow such as avoidable `goto` if there is a cleaner bounded alternative, name any local helper APIs or maintainer conventions the patch should follow, and keep the intended maintainer-facing explanation clear enough that someone unfamiliar with the local complaint wording can still follow the fix. In `## Validation`, name the reproducible configure/build/test entrypoint you will try from the workspace root before any focused leaf compile or smoke check, and include one bounded independent reproduction attempt for the collected failure signal when it is safe and cheap. Do not plan to claim `reproduced` unless that reproduction command or test can actually show the failure.
## Patch Pass
You are working on a bounded fixer proposal.
Read the evidence bundle at `./evidence.json`. The prepared workspace is `./workspace` and it was acquired via `debian-source`. Produce the smallest reasonable patch for the target repository, keep the change upstreamable, prefer the clearest control flow available, and do not keep avoidable `goto` when a simpler structure would read better. Before introducing new file, process, allocation, locking, networking, or platform APIs, inspect nearby code and project contribution docs for existing helpers or compatibility wrappers and use those local patterns unless you can explain why they do not fit. Validate from a reproducible workspace-root entrypoint before falling back to focused leaf commands; if a build or test cannot run, report the exact command, the exact blocker, and any narrower check you ran instead. During validation, also try one bounded independent reproduction of the collected failure signal when it is safe and cheap, such as a failing test, smoke command, perf/strace comparison, or before/after runtime check. Only use `reproduced` if that command or test actually reproduced the failure; otherwise keep `observed` and report the reproduction blocker. The final explanation must connect the observed issue evidence to the actual code change, not just paraphrase the diff. Write like a maintainer is going to read the patch mail cold: explain the bug in plain language, define subsystem-specific jargon the first time you need it, and make the causal story obvious. Explicitly classify evidence confidence as `reproduced`, `observed`, or `inferred`: `reproduced` means you reproduced the failure locally; `observed` means Fixer has direct crash/log/trace evidence but you did not independently reproduce it; `inferred` means the source patch is not pull-request-ready, so do not leave a source diff unless you first gather stronger observed/reproduced evidence; otherwise return a no-patch diagnosis/report. For any source-changing `observed` patch, say explicitly in `## Issue Connection` that the failure was observed by Fixer and not independently reproduced. If you introduce non-obvious state translation, index remapping, or backend split logic, add a short source comment that explains the invariant being preserved.
Start by explaining the likely root cause from the collected perf, strace, and /proc evidence. If you cannot land a safe patch, leave a diagnosis that is strong enough for an upstream bug report.
Upstream-style expectation: before planning or editing, check for contribution/style docs (`CONTRIBUTING`, `HACKING`, `README-hacking`, `README.md`, `docs/`, `dev-docs/`) and scan the touched subsystem for local helpers. If the project has wrappers for file IO, path-relative IO, process spawning, memory allocation, logging, locking, or platform compatibility, prefer those wrappers over generic libc/std APIs. Do not invent a reproducer or user-visible failure that is not in the evidence bundle; if the evidence is profiler-only or indirect, describe it as a targeted mitigation or stop with a diagnosis instead of presenting a speculative patch as a confirmed bug fix. In the plan and final validation, name any such helper, convention, or evidence limit you found, or say that no relevant local helper was found. Treat this as a `docker.io` upstream patch, not just a Debian-local workaround.
Keep the change narrowly scoped and summarize validation clearly.
In every authoring pass, your final response must start with `Subject: <single-line git commit subject>` and then include these markdown sections exactly:
## Commit Message
A short upstream-friendly explanation of what changed and why. Write it in plain language that a maintainer can follow without local complaint context. If you use subsystem jargon, define it immediately.
## Evidence Confidence
Exactly one word: `reproduced`, `observed`, or `inferred`. Use `reproduced` only when you reproduced the failure locally with a command or test, and include that command/test in `## Validation`. Use `observed` when Fixer has direct crash/log/trace evidence but you did not independently reproduce it. If `## Git Add Paths` lists source files for an `observed` patch, `## Issue Connection` must explicitly say the failure was observed by Fixer and not independently reproduced. Use `inferred` for profiler/strace/indirect evidence; inferred responses may be no-patch diagnoses or reports, but inferred source patches are not pull-request-ready until stronger evidence is gathered.
## Issue Connection
Write this as maintainer-facing patch mail, not as local Fixer notes. Cover four things explicitly in readable sentences: the user-visible symptom or the exact collected signal, the code-level cause or the cautious inference from evidence, the specific change you made, and the expected effect. Do not invent a reproducer, command line, crash, or user-visible failure that is not present in the evidence bundle. If the evidence is direct-but-not-reproduced, say it was observed by Fixer and not independently reproduced. If the evidence is indirect and you did not gather stronger evidence, do not leave a source diff; write a no-patch diagnosis/report instead. Include an explicit effect sentence such as `The expected effect is ...`, `This should reduce ...`, or `This prevents ...` for source patches. If the logic is non-obvious in code, mention that you added a short explanatory comment.
## Git Add Paths
List the repo-relative paths that belong in the final patch, one per line. Use `None` only when you intentionally made no source changes. Include intentionally new files, and do not list generated build artifacts.
## Validation
List the checks you ran, or say clearly that you could not run them. Include the independent reproduction command/test and result when `## Evidence Confidence` is `reproduced`; if reproduction was attempted but blocked, name the exact blocker and keep confidence at `observed` or `inferred`.
Before editing, read the plan at `./plan-output.txt` and follow it unless the code proves part of it wrong. If you change course, say so explicitly in the final write-up instead of silently drifting from the plan.
## Review Pass 1
You are reviewing a freshly generated fixer patch.
Read the evidence bundle at `./evidence.json`. The prepared workspace is `./workspace` and it was acquired via `debian-source`. Review the first patch pass. The original pre-edit snapshot is available at `./source` for diffing.
Upstream-style expectation: before planning or editing, check for contribution/style docs (`CONTRIBUTING`, `HACKING`, `README-hacking`, `README.md`, `docs/`, `dev-docs/`) and scan the touched subsystem for local helpers. If the project has wrappers for file IO, path-relative IO, process spawning, memory allocation, logging, locking, or platform compatibility, prefer those wrappers over generic libc/std APIs. Do not invent a reproducer or user-visible failure that is not in the evidence bundle; if the evidence is profiler-only or indirect, describe it as a targeted mitigation or stop with a diagnosis instead of presenting a speculative patch as a confirmed bug fix. In the plan and final validation, name any such helper, convention, or evidence limit you found, or say that no relevant local helper was found. Treat this as a `docker.io` upstream patch, not just a Debian-local workaround. The latest author response is at `./patch-output.txt`. Inspect the current code and changed paths like a strict code reviewer. Focus on correctness, regressions, maintainability, awkward control flow such as avoidable `goto`, missing validation, weak or non-gittable commit message text, and explanations that fail to connect the observed issue evidence to the code change. Also review the maintainer experience: the patch mail should be easy to accept upstream, the user-visible bug should be explained in plain language, subsystem-specific jargon should be defined when first used, and any non-obvious state translation or index remapping in code should have a short explanatory comment. Reject patches that omit `## Evidence Confidence`, use anything other than `reproduced`, `observed`, or `inferred`, or sound more certain than that evidence level allows. Reject patches that claim `reproduced` unless `## Validation` names the concrete reproduction command or test and its result. Reject patches that invent a reproducer, command line, crash, or user-visible failure not present in the evidence bundle; indirect profiler or strace evidence may justify a cautious mitigation, but the author must say it is indirect instead of presenting it as a confirmed upstream bug. Reject patches that introduce generic libc/std APIs when nearby code or project docs provide a local compat/helper API for the same job, unless the author explicitly justifies the exception. Reject validation that only reports a leaf object/syntax build when a project-level configure/build/test entrypoint exists and was not attempted; if a full build cannot run, the author must show the exact failed command and blocker.
Do not apply code changes in this pass.
Return a short markdown review report. The first non-empty line must be exactly one of:
RESULT: ok
RESULT: fix-needed
If you choose `RESULT: fix-needed`, add a `## Findings` section with concrete, actionable items.
Response
## Plan Pass
## Problem
Fixer observed an installed `/usr/sbin/dockerd` process started as `dockerd -H fd:// --containerd=/run/containerd/containerd.sock` with 185 threads, low CPU, sleeping state, and traces dominated by futex waits. The bundle labels the loop as “socket-churn,” but the included excerpts mostly show Go runtime futex waits and unresolved frames, not a specific Moby source path.
## Evidence Confidence
inferred
## Proposed Subject
No source patch yet: diagnose unresolved `dockerd` runtime/futex profile before changing Moby daemon code.
## Patch Plan
Do not edit code in this pass. The current evidence is not source-actionable enough for an upstream-quality patch: `/usr/sbin/dockerd` is stripped, raw artifact paths are unavailable in this workspace, and `go tool addr2line` maps sampled offsets to Go runtime/internal syscall frames rather than a stable `engine/daemon` caller.
If more evidence is collected before editing, first target the daemon entrypoint path `engine/cmd/dockerd/docker.go` and `engine/cmd/dockerd/daemon.go`, then daemon startup/container restore code in `engine/daemon/daemon.go`. Local conventions/helpers found: `github.com/containerd/log` via `log.G(ctx)`, `github.com/pkg/errors` wrapping, `pkg/pidfile`, `pkg/homedir`, `daemon/listeners`, `user.MkdirAllAndChown`, `golang.org/x/sync/semaphore`, and `errgroup.SetLimit` patterns. Follow Moby’s `gofmt -s` and unit-test expectations from `engine/CONTRIBUTING.md` and `engine/TESTING.md`.
No prior Fixer patch is present to replace; the workspace only has `Fixer baseline`, and it matches the original dfsg4 source aside from workspace metadata. Avoid speculative control-flow changes such as adding `goto` exits around daemon startup; if later evidence points to excessive goroutine fanout, prefer a bounded worker/errgroup or existing semaphore pattern.
## Risks
A patch based only on the current bundle would likely treat normal idle Go runtime futex waits as a daemon bug. The observed package version was `28.5.2+dfsg3-2`, while this workspace is `28.5.2+dfsg4`, so the sampled binary may not exactly match the prepared source. Attaching tracing to a live daemon can perturb timing and should stay bounded.
## Validation
Before any future focused check, try the reproducible package entrypoint from the workspace root: `DEB_BUILD_OPTIONS=nocheck dpkg-buildpackage -us -uc -b` or, for the upstream engine test entrypoint, `cd engine && ./hack/test/unit`.
Bounded independent reproduction attempt: if a disposable or local `dockerd` is running, collect `timeout 5s ps -o pid,stat,pcpu,nlwp,wchan -C dockerd` plus `timeout 5s strace -f -c -p "$(pidof dockerd)"` to confirm whether the current signal is actually socket churn or mostly futex sleep. Do not claim reproduced unless that command shows the same failure signal.
## Patch Pass
Subject: Diagnose unresolved dockerd futex profile
## Commit Message
No source change was made. The collected signal points to `dockerd` threads parked in Go runtime futex waits, but the evidence does not identify a Moby source-level loop or retry path that can be fixed safely.
I followed the saved plan. I inspected Moby contribution/testing docs and daemon code conventions, including `log.G(ctx)`, `github.com/pkg/errors`, `pkg/pidfile`, `daemon/listeners`, `user.MkdirAllAndChown`, and the existing `semaphore.NewWeighted` startup throttling pattern.
## Evidence Confidence
inferred
## Issue Connection
The collected signal is a sleeping `dockerd` process with 185 threads, low CPU, `/proc` scheduler data showing mostly voluntary switches, and `strace` excerpts dominated by unfinished `futex(FUTEX_WAIT_PRIVATE, ...)` calls. Although the bundle labels the profile as “socket-churn,” the shown syscall and stack excerpts are futex waits, and the sampled binary frames are unresolved.
The likely root cause of the collected signal is that the profiler sampled idle or parked Go runtime threads rather than a demonstrated Docker daemon socket retry loop. I did not find symbolized evidence tying the sampled frames to `engine/cmd/dockerd`, `engine/daemon`, listener setup, containerd dialing, or daemon startup restore code. The daemon startup code does use semaphores to bound parallel container work, but the current evidence does not show that path was active or pathological.
Because this remains indirect profiler evidence, I made no source change. The expected effect is to avoid landing a speculative upstream patch for a normal-looking futex wait profile without a source-specific failure signal.
## Git Add Paths
None
## Validation
`timeout 5s sh -c 'pid=$(pidof dockerd 2>/dev/null || true); if [ -z "$pid" ]; then echo "no dockerd pid"; exit 2; fi; ps -o pid,stat,pcpu,nlwp,wchan,cmd -p "$pid"; if command -v strace >/dev/null 2>&1; then timeout 5s strace -f -c -p "$pid"; else echo "strace not installed"; exit 3; fi'`
Result: blocked; no local `dockerd` pid was running, so I could not independently reproduce the futex/thread signal.
`DEB_BUILD_OPTIONS=nocheck dpkg-buildpackage -us -uc -b`
Result: blocked by unmet Debian build dependencies, starting with `dh-golang`, `golang-any`, `go-md2man`, and many Go library packages.
`git diff --stat`
Result: no source changes.
## Review Pass 1
RESULT: ok
The review passes. The workspace has no source changes relative to the original snapshot, and `patch-output.txt` correctly treats the evidence as `inferred` rather than forcing a speculative patch.
The author response includes the required sections, uses a valid evidence confidence value, does not claim reproduction, and reports both the bounded reproduction blocker (`no dockerd pid`) and the workspace-root build blocker (`dpkg-buildpackage` unmet build dependencies). It also names the relevant Moby conventions/helpers inspected and explains why the profiler/futex evidence is not source-actionable.