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https://issues.apache.org/jira/browse/CALCITE-7632?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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ASF GitHub Bot updated CALCITE-7632:
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Labels: pull-request-available (was: )
> Replace java.util.Stack with java.util.ArrayDeque in Pattern and
> TopDownRuleDriver
> ----------------------------------------------------------------------------------
>
> Key: CALCITE-7632
> URL: https://issues.apache.org/jira/browse/CALCITE-7632
> Project: Calcite
> Issue Type: Improvement
> Components: core
> Reporter: Liu Zhengri
> Priority: Major
> Labels: pull-request-available
>
> Replace `java.util.Stack` (which extends `Vector` with unnecessary
> synchronization overhead) with `java.util.ArrayDeque` in two locations:
> 1. `Pattern.java` - `PatternBuilder.stack` field (used for SQL
> MATCH_RECOGNIZE NFA pattern matching)
> 2. `TopDownRuleDriver.java` - task queue (used for Volcano optimizer top-down
> Cascades-style optimization)
> This eliminates the `@SuppressWarnings("JdkObsolete")` annotations and `//
> TODO: replace with Deque` comments that have existed since CALCITE-4314
> (2020).
> Benefits:
> - `Stack` extends `Vector` with synchronized methods (unnecessary lock
> overhead in single-threaded contexts)
> - `ArrayDeque` is non-synchronized and officially recommended by Java
> documentation as a replacement for `Stack`
> - Removes Error Prone `JdkObsolete` warnings
> - Better memory expansion strategy (ArrayDeque doubles capacity vs Vector
> linear growth)
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