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fix(server): timed-out status fetches no longer leave partial packs behind - #16780
louisgundelwein wants to merge 2 commits into
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…ehind The background status fetch is killed after 5s. Git leaves the partial tmp_pack_* behind even on SIGTERM, and every retry downloads the backlog again, so a repo with a large fetch backlog collects one partial pack per retry until the disk fills. A failed or interrupted status fetch now removes the temporary pack files that appeared while it ran. Files that existed before the fetch are left alone.
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ApprovabilityVerdict: Approved at Macroscope's review found this PR approvable — This is a narrowly scoped server bug fix that cleans up only temporary pack files created by failed background status fetches, while preserving existing files and errors. The added focused test covers timeout cleanup and concurrent-existing temporary files, with no schema, default, deployment, or security impact. You can add or adjust custom eligibility rules. Learn more. |
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Included review availability: This review used your included allowance. Your plan provides up to 10 included reviews per hour; 9 remain after this review. 📝 WalkthroughWalkthroughThe status fetch snapshots temporary pack files before fetching. After a failed fetch, it best-effort removes newly appearing temporary pack files if the snapshot succeeded. If the initial listing fails, it skips cleanup. Tests cover both cases and verify that pre-existing files remain. ChangesStatus Fetch Cleanup
Priority: ⬇️ Low Estimated code review effort: 2 (Simple) | ~10 minutes Change: Bug fix Suggested reviewers: Merge Risk: 🔵 Low · up to A failed status fetch can occasionally interrupt another fetch in the same repository. The affected fetch can be retried, but the concurrent-operation risk remains and should be accepted or addressed before merging. Security Architecture ReviewSecurity architecture risk: 🟡 Moderate · up to The cleanup reduces disk accumulation, but it can mistake a concurrent Git operation’s temporary pack for its own and delete it. This can disrupt operations sharing the same repository, including linked worktrees. Retained concerns
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Actionable comments posted: 2
- 🪄 Fix CodeRabbit comments on this PR
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Inline comments:
Review comments at @apps/server/src/vcs/GitVcsDriverCore.ts:
- Around line 1246-1247: Update the cleanup around the `current.filter` and
`fileSystem.remove` calls so a failed status fetch deletes only temporary pack
files it can prove it created itself. Do not treat files that appeared after the
baseline read as owned solely because their names are new.
- Line 1213: Update the baseline read fallback at Effect.orElseSucceed so only
an absent pack directory is treated as empty. Preserve other read failures as an
unknown baseline, and skip deletion during that attempt rather than treating
existing files as absent.
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apps/server/src/vcs/GitVcsDriverCore.test.tsapps/server/src/vcs/GitVcsDriverCore.ts
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A failed baseline listing used to count as an empty directory, so every existing tmp_* file looked new and could be removed. Only a missing pack directory counts as empty now. Any other read failure skips cleanup for that attempt.
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Problem
The background status fetch (
fetchRemoteForStatus) is killed after 5s. Git leaves the partialtmp_pack_*behind when that happens, even on the SIGTERM the process runner sends to the group. Retries back off to every 15 minutes, and each one downloads the whole backlog again, so a repo whose fetch takes longer than 5s collects one partial pack per retry. On my machine that was 84 files and about 13 GB in one repo over a day (a game repo with a ~4 GB fetch backlog). Reported in #3525.#13812 fixed the auto-gc variant of this leak and notes that the timeout variant is still open. The maintainer comment closing #4338 says the same: #4338 (comment)
Change
Before the status fetch runs, list the
tmp_*files in<gitCommonDir>/objects/pack. If the fetch fails, times out or is interrupted, remove thetmp_*files that were not there before. Removal is best effort and does not change the returned error or the backoff. If the listing before the fetch fails for any reason other than a missing pack directory, that attempt removes nothing, since it cannot tell which files are its own.This is a much smaller alternative to #4338. It does not change the timeout or the retry cadence. A backlog that never fits in 5s still gets downloaded again on each retry. That is a separate problem and is not addressed here.
Scope and approval
Bug fix for #3525. One problem: partial packs left behind by a failed status fetch.
Verification
Git leaves the file on SIGTERM (git 2.54.0, macOS). I spawned
git fetch --quiet --no-tags --no-auto-gc originin its own process group, the way the Node spawner does, against a local remote whose upload-pack is throttled to about 2 MB/s and has 300 objects, so index-pack is used. After 8s I sent SIGTERM to the group.tmp_pack_*was present before the signal and still there afterwards. Same result with SIGKILL.End to end with the real driver. A stale clone of that throttled remote, with
driver.statusDetailsRemote()called through the real spawner, real git and the real 5s timeout. I used a temporary test that is not committed.tmp_pack_WOPuZL(7.9 MB) is left inobjects/packafter the call.pack-*.{pack,idx,rev}, over two runs.Focused test.
removes the partial pack a timed-out status fetch leaves behindinGitVcsDriverCore.test.ts. It uses a spawner whose fetch writes atmp_packand never exits, then moves the TestClock past the timeout. It also checks that atmp_packthat existed before the fetch is kept.A second case fails the pre-fetch listing once (PermissionDenied) and checks that both files survive. It fails on the first revision of this PR and passes now.
expected [ 'tmp_pack_other', …(1) ] to deeply equal [ 'tmp_pack_other' ]vp test run src/vcs/GitVcsDriverCore.test.tsgives 133/133. Servervp run typecheckexits 0, andvp fmt --checkis clean on both files.Concurrent fetch edge case. A user fetch that starts during the 5s window could have its
tmp_packremoved by this cleanup. I deleted thetmp_packunder a running fetch to check what happens. That fetch fails cleanly (exit 128,unable to rename temporary '*.pack' file), and no refs are updated.git fsckreports a clean repo, and rerunning the fetch succeeds.Not checked: Windows. There, unlink of a file still held open may fail with EBUSY. The error is ignored, so the worst case is the old behavior.