[HBASE-10263] make LruBlockCache single/multi/in-memory ratio user-configurable and provide preemptive mode for in-memory type block

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.98.0, 0.99.0
• Component/s: io
• Hadoop Flags: Reviewed

Release Note

4 new configurations are introduced:
hbase.lru.blockcache.single.percentage / hbase.lru.blockcache.multi.percentage / hbase.lru.blockcache.memory.percentage / hbase.lru.rs.inmemoryforcemode
the first 3 enable user to config different single/multi/memory ratio in block cache; the last one determines if preemptive mode for memory block is enabled

• Assignee: Honghua Feng
• Reporter: Honghua Feng
• Created: 31/Dec/13 12:14
• Updated: 21/Feb/15 23:34
• Resolved: 11/Jan/14 01:30

Description

currently the single/multi/in-memory ratio in LruBlockCache is hardcoded 1:2:1, which can lead to somewhat counter-intuition behavior for some user scenario where in-memory table's read performance is much worse than ordinary table when two tables' data size is almost equal and larger than regionserver's cache size (we ever did some such experiment and verified that in-memory table random read performance is two times worse than ordinary table).

this patch fixes above issue and provides:
1. make single/multi/in-memory ratio user-configurable
2. provide a configurable switch which can make in-memory block preemptive, by preemptive means when this switch is on in-memory block can kick out any ordinary block to make room until no ordinary block, when this switch is off (by default) the behavior is the same as previous, using single/multi/in-memory ratio to determine evicting.

by default, above two changes are both off and the behavior keeps the same as before applying this patch. it's client/user's choice to determine whether or which behavior to use by enabling one of these two enhancements.