rsync likely remains stuck in a busy-poll 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.
Validation expectation: try the project-level build/test entrypoint from the workspace root before reporting only a focused leaf compile. Detected candidate(s): `./configure && make`. If the project-level command fails because dependencies or generated files are missing, include the exact command and failure reason in `## Validation`, then run the narrowest relevant compile/test that is still reproducible from a clean checkout.
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 `rsync` 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.
Validation expectation: try the project-level build/test entrypoint from the workspace root before reporting only a focused leaf compile. Detected candidate(s): `./configure && make`. If the project-level command fails because dependencies or generated files are missing, include the exact command and failure reason in `## Validation`, then run the narrowest relevant compile/test that is still reproducible from a clean checkout.
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 `rsync` 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 `rsync` upstream patch, not just a Debian-local workaround.
Validation expectation: try the project-level build/test entrypoint from the workspace root before reporting only a focused leaf compile. Detected candidate(s): `./configure && make`, `make` and, if available, `make check`. If the project-level command fails because dependencies or generated files are missing, include the exact command and failure reason in `## Validation`, then run the narrowest relevant compile/test that is still reproducible from a clean checkout. 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 Debian `rsync` 3.4.1 process with repeated `pselect6`/`read` cycles and classified it as a likely busy-poll loop. The strace excerpts show blocking `pselect6` calls followed by 8-byte reads such as `\4\0\0kkz\0\0`, which decode as short multiplexed `MSG_DATA` packets. In rsync, `io.c` uses empty `MSG_DATA` packets as keep-alives via `maybe_send_keepalive()`.
## Evidence Confidence
inferred
## Proposed Subject
No source patch yet: diagnose observed rsync trace as keep-alive traffic already related to upstream 3.4.2 timeout changes
## Patch Plan
I do not plan a source edit from the current evidence alone. The evidence is profiler/strace-only, from installed `3.4.1+ds1-7`, while this workspace is `3.4.2+ds1-2`; `NEWS.md` says 3.4.2 fixed “too-aggressive keep-alive messages” for older rsyncs early in transfer.
If later evidence reproduces the issue against this 3.4.2 tree, the patch should be in `io.c`, around `maybe_send_keepalive()`, `check_timeout()`, and `perform_io()`, using existing helpers/conventions: `send_msg()`, `io_flush()`, `set_io_timeout()`, `rprintf()`/`rsyserr()`, and rsync’s existing bounded control flow. Avoid adding an avoidable `goto`; nearby code has some historical `goto`, but a local boolean/time guard would be cleaner if throttling is needed.
No prior Fixer patch was found in `debian/patches`; existing Debian patches do not touch this I/O loop.
## Risks
A speculative throttle could break legitimate `--timeout` behavior, especially generator/receiver liveness during large-file checksum or deletion phases. It could also regress compatibility with older protocol keep-alive handling.
## Validation
Before any focused check after a real patch, try the project entrypoint from the workspace root:
`./configure && make`
Then run the narrowest relevant check, likely a local rsync transfer under `strace -f -tt -e pselect6,select,read,write` with a small `--timeout` to observe whether empty `MSG_DATA` keep-alives are emitted at an expected bounded cadence. This would be a bounded signal check only; it should not be reported as reproducing the original runaway unless it shows nonblocking repeated poll/read behavior with elevated CPU on 3.4.2.
## Patch Pass
Subject: Diagnose rsync keep-alive poll trace without source changes
## Commit Message
No source change is included. The collected signal is an indirect runtime trace from installed rsync 3.4.1, and the 3.4.2 source tree already contains related keep-alive handling for this area. A source patch would be speculative without reproducing the behavior against this tree.
## Evidence Confidence
inferred
## Issue Connection
Fixer collected a perf/strace signal where rsync repeatedly returned from `pselect6` and read short 8-byte packets while the process was sleeping in `poll_schedule_timeout`. Those packets decode like rsync multiplexed-I/O `MSG_DATA` keep-alive packets, where multiplexed I/O is rsync’s control-message stream interleaved with file data.
The cautious code-level inference is that the trace is tied to timeout keep-alive behavior in `io.c`, especially `maybe_send_keepalive()`, `send_msg(MSG_DATA, "", 0, 0)`, `set_io_timeout()`, and `perform_io()`. The evidence was collected from installed `3.4.1+ds1-7`, while this workspace is `3.4.2+ds1-2`; `NEWS.md` already notes a 3.4.2 fix for too-aggressive keep-alive messages early in a transfer.
I made no source change. This follows the saved plan instead of adding a speculative throttle that could break legitimate `--timeout` liveness handling between sender, receiver, and generator processes. The expected effect is no behavior change from this proposal; the useful upstream report is that any further patch needs a reproduction or trace against 3.4.2.
Style/helper scan: only `README.md` and `doc/` were present from the requested contribution-doc list. The relevant local helpers are rsync’s existing `send_msg()`, `io_flush()`, `set_io_timeout()`, `rprintf()`, and `rsyserr()` conventions. No prior Fixer patch was found in `debian/patches`.
## Git Add Paths
None
## Validation
`./configure && make` failed from the workspace root during configure:
`config.status: error: cannot find input file: 'zlib/dummy.in'`
`./configure --with-included-zlib=no && make` failed with the same blocker because `configure.ac` unconditionally lists `zlib/dummy` in `AC_CONFIG_FILES`.
Focused compile attempt:
`make io.o` failed with `make: *** No rule to make target 'config.h', needed by 'io.o'. Stop.`
Independent reproduction attempt:
`strace -f -tt -e trace=pselect6,select,read,write ... /usr/bin/rsync ...` was blocked by sandbox ptrace restrictions: `PTRACE_TRACEME: Operation not permitted`; the trace file was empty. A bounded local smoke transfer with `/usr/bin/rsync -a --timeout=1` exited 0 and copied one file, but it did not reproduce the collected poll/read signal.
## Review Pass 1
RESULT: ok
No blocking findings. The generated pass correctly leaves no source diff for `inferred` evidence, does not overclaim reproduction, and explains the likely keep-alive/multiplexed-I/O interpretation without presenting it as a confirmed upstream bug.
Validation is acceptable for a no-patch diagnosis: the project-level `./configure && make` was attempted and the `zlib/dummy.in` blocker is reported. The ignored generated files left by configure are not listed in `## Git Add Paths` and `git diff` is clean.
Diff
--- a/lib/dummy 1970-01-01 04:00:00.000000000 +0400
+++ b/lib/dummy 2026-05-13 09:51:03.353270070 +0400
@@ -0,0 +1,2 @@
+This is a dummy file to ensure that the lib directory gets created
+by configure when a VPATH is used.