[jira] [Commented] (CALCITE-4358) Potential memory leak in VolcanoPlanner#materializations due to circular reference

["Stamatis Zampetakis (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CALCITE-4358?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17221377#comment-17221377 ] 

Stamatis Zampetakis commented on CALCITE-4358:
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One question is do you keep RelOptMaterialization somewhere else outside of Calcite? I don't think circular reference is a problem unless one part of the circle is referenced and kept by your code.

> Potential memory leak in VolcanoPlanner#materializations due to circular reference
> ----------------------------------------------------------------------------------
>
>                 Key: CALCITE-4358
>                 URL: https://issues.apache.org/jira/browse/CALCITE-4358
>             Project: Calcite
>          Issue Type: Bug
>          Components: core
>            Reporter: Jiatao Tao
>            Assignee: Jiatao Tao
>            Priority: Major
>
> Hi fellows
> We use Calcite's materialization view in our product env, and it OOM times, I dig the memory dump and found there are all of RelOptMaterialization instance.
>  
> We will call Planner#clear before every query and will new a new Planner just as org.apache.calcite.prepare.CalcitePrepareImpl did, and inside the dump, there are lots of planner instance, so I suspect it is a circular reference that JVM can not GC them, here's the chain:
>  
> 1. org.apache.calcite.plan.volcano.VolcanoPlanner#materializations: List<RelOptMaterialization> 2. org.apache.calcite.plan.RelOptMaterialization#queryRel: AbstractRelNode 3. org.apache.calcite.rel.AbstractRelNode#cluster: RelOptCluster 4. org.apache.calcite.plan.RelOptCluster#planner: VolcanoPlanner 5. org.apache.calcite.plan.volcano.VolcanoPlanner#materializations: List<RelOptMaterialization>



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