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https://issues.apache.org/jira/browse/IGNITE-4426?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Vladimir Ozerov resolved IGNITE-4426.
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Resolution: Fixed
> Hadoop: allow optional classloader reuse between tasks.
> -------------------------------------------------------
>
> Key: IGNITE-4426
> URL: https://issues.apache.org/jira/browse/IGNITE-4426
> Project: Ignite
> Issue Type: Sub-task
> Components: hadoop
> Affects Versions: 1.8
> Reporter: Vladimir Ozerov
> Assignee: Vladimir Ozerov
> Fix For: 2.0
>
>
> *Problem*
> Currently we create separate {{HadoopClassLoader}} for each and every MR
> task. It has serious performance implications:
> 1) Every task have to reload classes form disk;
> 2) Every task starts from "cold" state with not-compiled classes;
> 3) Very high permgen/metaspace and code cache regions usage.
> We can observe, that every task classloader works with the same JARs. It
> means that the only case when we really need to isolate tasks through
> classloaders is when they depend on some static data, which should not be
> shared.
> *Proposal*
> - Share {{HadoopClassLoader}} between tasks by default;
> - Allow to optionally disable this opto.
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