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fix(object_store): probe a stale first bucket before it has a median - #204
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Canceled copies raise an unmeasured bucket's routing latency until a read succeeds or a recovery probe clears it. Staleness probes required a median, so a first bucket that canceled copies ranked behind its peers before any read succeeded was never probed, and hedges and fallback chose peers ahead of it, leaving it bypassed indefinitely. Closes #203 Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
 [Medium impact] The PR appears safe to merge. SummaryAllows a stale first bucket to receive a recovery probe before it has a measured median.
No actionable issues found. Tests were not run. Reviews (1) · Last reviewed commit: "fix(object_store): probe a stale first b..." · Reviewed by Greptile |
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## 🤖 New release * `cachey`: 0.13.1 -> 0.13.2 <details><summary><i><b>Changelog</b></i></summary><p> <blockquote> ## [0.13.2](0.13.1...0.13.2) - 2026-10-29 ### Added - *(service)* resolve millisecond latencies in download and first chunk histograms ([#207](#207)) - *(service)* report hedge delays in place of raw phase latency ([#206](#206)) ### Fixed - *(object_store)* probe a stale first bucket before it has a median ([#204](#204)) </blockquote> </p></details> --- This PR was generated with [release-plz](https://github.com/release-plz/release-plz/). Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
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Closes #203
Since #182, canceled copies raise an unmeasured bucket's routing latency (
unmeasured_latency), which only a successful read or a recovery probe clears.RoutingSnapshot::primary()only staleness-probed buckets with a median, so a first bucket that canceled copies had ranked behind its peers before any read succeeded was never probed. Hedges and fallback pick the best untried bucket, which with three or more buckets is another peer, so the first bucket could be bypassed indefinitely. This contradictsdocs/replica-reads.md, which says the first bucket is probed regardless.The first bucket is now considered stale after 30 s without an outcome whether or not it has a median. Peers without a median are still not staleness-probed, as since #139.
probe_afterstill spaces repeat probes.a_stale_unmeasured_first_bucket_is_probedfails onmainand passes with the fix.🤖 Generated with Claude Code