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https://issues.apache.org/jira/browse/PHOENIX-7990?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Tanuj Khurana resolved PHOENIX-7990.
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Resolution: Fixed
> Convergent CAS race in setHAGroupStatusIfNeeded aborts co-active
> RegionServers on stale-version loss
> ----------------------------------------------------------------------------------------------------
>
> Key: PHOENIX-7990
> URL: https://issues.apache.org/jira/browse/PHOENIX-7990
> Project: Phoenix
> Issue Type: Sub-task
> Reporter: Tanuj Khurana
> Assignee: Tanuj Khurana
> Priority: Major
>
> When two or more active RegionServers react to the same peer-degrade event,
> each independently attempts to move the shared HA-status znode from
> ACTIVE_IN_SYNC → ACTIVE_NOT_IN_SYNC via an optimistic compare-and-swap (CAS).
> The expected version for the CAS comes from the watch-lagged local cache. The
> first writer wins; the remaining writers CAS against a now-stale version,
> receive StaleHAGroupStoreRecordVersionException, and abort the RegionServer —
> even though the shared status has already reached the exact value they
> intended to write.
> Unnecessary RegionServer aborts during a normal convergent reaction to a peer
> degrade. The write is idempotent at the group level, so a peer having already
> set the target state is a success condition, not a conflict — but the code
> treated it as fatal.
> Root cause
> The validate → build → CAS body ran exactly once against a single
> cache-derived (record, version) snapshot. Any lost CAS propagated as an
> exception with no reconciliation against the actual current ZK state.
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