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fix(git): stop snapshot generation from stalling every request - #412
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Ref-check and last-fetch bookkeeping took the repository RWMutex for writing on every request and every fetch. Snapshot generation holds that lock for reading for minutes on large mirrors, and a queued writer makes RWMutex park every new reader behind it, so serving (State(), for-each-ref, snapshot downloads) hung until generation finished and clients timed out. Move the bookkeeping to its own mutex so only state transitions ever write the repository lock. Also fetch and retry the mirror when upload-pack reports "not our ref" before forwarding to upstream: on busy repositories the missing object is almost always a commit the stale mirror simply has not fetched yet, and forwarding proxied the entire pack from upstream. Tests: the quay.io/minio/minio image is no longer published, so the S3 test container now uses cgr.dev/chainguard/minio.
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Ref-check and last-fetch bookkeeping took the repository
RWMutexfor writing on every request and every fetch. Snapshot generation holds that lock for reading for minutes on large mirrors, and a queued writer parks every new reader behind it, so serving hung until generation finished. The bookkeeping now lives under its own mutex; only state transitions write the repository lock.Also fetch and retry the mirror when upload-pack reports "not our ref" before forwarding to upstream. On busy repositories the missing object is usually a commit the stale mirror has not fetched yet, and forwarding proxied the whole pack from upstream.
Tests:
quay.io/minio/miniois no longer published (CI has been failing onmainsince Sep 24), so the S3 test container now usescgr.dev/chainguard/minio.