[CASSANDRA-6838] FileCacheService overcounting its memoryUsage

• Type: Bug
• Status: Resolved
• Priority: Low
• Resolution: Fixed
• Fix Version/s: 2.0.7, 2.1 beta2
• Labels: performance
• Severity: Low
• Assignee: Benedict Elliott Smith
• Reporter: Benedict Elliott Smith

Authors

Benedict Elliott Smith

Reviewers

Jonathan Ellis

• Created: 12/Mar/14 00:52
• Updated: 16/Apr/19 09:31
• Resolved: 12/Mar/14 04:20

Description

On investigating why I was seeing dramatically worse performance for counter updates over prepared CQL3 statements compred to unprepared CQL2 statements, I stumbled upon a bug in FileCacheService wherein, on returning a cached reader back to the pool, its memory is counted again towards the total memory usage, but is not matched by a decrement when checked out. So we effectively are probably not caching readers most of the time.