[ACCUMULO-599] investigate permgen collection and class unloading with concurrent mark and sweep garbage collector

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Not A Problem
• Affects Version/s: 1.3.6, 1.4.0
• Component/s: scripts
• Assignee: Eric C. Newton
• Reporter: Adam Fuchs
• Created: 18/May/12 20:59
• Updated: 31/Mar/16 13:19
• Resolved: 06/Aug/14 20:21

Description

The Java concurrent mark and sweep garbage collector appears to default to not unloading classes or sweeping the permgen storage space. Accumulo reloads classes dynamically, potentially contributing a lot to the permgen space. It is important that these classes be garbage collected when we're done with them. Since we use -XX:+UseConcMarkSweepGC by default for all Accumulo processes, should we also use -XX:+CMSClassUnloadingEnabled and -XX:+CMSPermGenSweepingEnabled? Are there other flags or parameters that we should set to really do java garbage collection properly in a long-lived instance?

These should be set in conf/accumulo-env.sh as part of ACCUMULO_GENERAL_OPTS.

Issue Links

• relates to: ACCUMULO-4169 TabletServer.config contextCleaner removes contexts that are not set on a table