fix: limit clone job concurrency to prevent scheduler deadlock#227
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fix: limit clone job concurrency to prevent scheduler deadlock#227
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Clone operations can take up to 30 minutes (CloneTimeout). When many simultaneous clones occur, they can consume all scheduler workers, starving fetch/repack/snapshot jobs and causing a full service outage. Add MaxCloneConcurrency config to limit how many clone jobs can run simultaneously, reserving remaining workers for other job types. Default: half of total concurrency (e.g., 4 of 8 workers for clones, leaving 4 for fetches/repacks/snapshots). Amp-Thread-ID: https://ampcode.com/threads/T-019d2b6c-0ae0-768e-b01c-7069931d6562 Co-authored-by: Amp <amp@ampcode.com>
stuartwdouglas
approved these changes
Mar 26, 2026
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Clone operations can take up to 30 minutes (CloneTimeout). When many simultaneous clones occur, they can consume all scheduler workers, starving fetch/repack/snapshot jobs and causing refs to go stale across all repos — resulting in a full service outage.
This adds a
MaxCloneConcurrencyconfig option to the scheduler that limits how many clone/deferred-mirror-restore jobs can run simultaneously. Remaining worker slots are reserved for fetch/repack/snapshot jobs, preventing clone starvation from causing a system-wide deadlock.Default behavior: When
max-clone-concurrencyis not set (0), it defaults to half of total concurrency. For example, withconcurrency = 32, at most 16 workers will be used for clones, leaving 16 available for fetches and other jobs.Config: