[CASSANDRA-5344] Make LCR less memory-abusive

• Type: Improvement
• Status: Resolved
• Priority: Low
• Resolution: Later
• Assignee: Unassigned
• Reporter: Jonathan Ellis
• Created: 13/Mar/13 22:07
• Updated: 16/Apr/19 09:32
• Resolved: 20/Nov/13 03:03

Description

We've seen several reports of compaction causing GC pauses. You would think this would be the fault of PCR (which materializes the rows in memory) but LCR seems to be more of a problem.

I hypothesize that PCR mostly generates just young-gen garbage, but since LCR keeps the BF and row index in-memory for a long time (from construction, until after the row has been merged and written), it gets tenured and can cause fragmentation or promotion failures.