[CASSANDRA-6944] liveRatio jumps to max when Memtable is empty

• Type: Bug
• Status: Resolved
• Priority: Low
• Resolution: Duplicate
• Labels: memtables

Environment

SUSE Linux Enterprise 11 (64-bit)

• Severity: Low
• Assignee: Aleksey Yeschenko
• Reporter: Erik Hansen

Authors

Aleksey Yeschenko

• Created: 27/Mar/14 20:49
• Updated: 16/Apr/19 09:31
• Resolved: 22/Apr/14 21:55

Description

liveRatio calculation on an empty memtable results in a value of Infinity since memtable.currentSize=0. Infinity then gets capped at the liveRatio max of 64.

WARN [MemoryMeter:1] 2014-03-19 09:26:59,483 Memtable.java (line 441) setting live ratio to maximum of 64.0 instead of Infinity
INFO [MemoryMeter:1] 2014-03-19 09:26:59,485 Memtable.java (line 452) CFS(Keyspace='system', ColumnFamily='compactions_in_progress') liveRatio is 64.0 (just-counted was 64.0).  calculation took 7ms for 0 cells

Jumping liveRatio to the max value based on an empty Memtable leads to more frequent flushing than may be necessary.

CASSANDRA-4243 previously addressed this issue, but was resolved as fixed by CASSANDRA-3741. It does not appear this issue has been fixed as of 2.0.5

Issue Links

• duplicates: CASSANDRA-6945 Calculate liveRatio on per-memtable basis, non per-CF