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https://issues.apache.org/jira/browse/CALCITE-1808?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16026683#comment-16026683
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Julian Hyde commented on CALCITE-1808:
--------------------------------------
Including the planner in the key of the cache wouldn't work. It would tend to
prevent planners from being garbage collected.
> JaninoRelMetadataProvider loading cache might cause OOM error
> -------------------------------------------------------------
>
> Key: CALCITE-1808
> URL: https://issues.apache.org/jira/browse/CALCITE-1808
> Project: Calcite
> Issue Type: Bug
> Components: core
> Reporter: Jagruti Varia
> Assignee: Julian Hyde
> Attachments: calcite-retained-strong-refs.png
>
>
> JaninoRelMetadataProvider has a static handler cache with size increasing
> over time for long running HS2, ending up causing OOM errors.
> {code:java}
> /** Cache of pre-generated handlers by provider and kind of metadata.
> * For the cache to be effective, providers should implement identity
> * correctly. */
> private static final LoadingCache<Key, MetadataHandler> HANDLERS =
> CacheBuilder.newBuilder().build(
> new CacheLoader<Key, MetadataHandler>() {
> public MetadataHandler load(@Nonnull Key key) {
> //noinspection unchecked
> return load3(key.def, key.provider.handlers(key.def),
> key.relClasses);
> }
> });
> ...
> /** Key for the cache. */
> private static class Key {
> public final MetadataDef def;
> public final RelMetadataProvider provider;
> public final ImmutableList<Class<? extends RelNode>> relClasses;
> ...
> {code}
> The lifecycle for providers is per query and we have multiple providers
> instantiated on the lifecycle of a query. The entries are retained in the
> cache even when query planning has finished.
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