[
https://issues.apache.org/jira/browse/HBASE-10263?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13869242#comment-13869242
]
Feng Honghua commented on HBASE-10263:
--------------------------------------
[~vrodionov] :
bq.I have always thought that artificial LruBlockCache divide on regular and
in-memory zones was not a good idea.
to some extent, I agree:-)
bq.The good cache implementation must sort all these things out itself
not quite...for some applications they need better latency for some table
regardless of what the table's access pattern is compared to other tables.
treating all the tables the same way and just letting the 'good' cache take
care of all of these is not desirable for such applications. for example think
about the META table(which is the internal in-memory table)
> make LruBlockCache single/multi/in-memory ratio user-configurable and provide
> preemptive mode for in-memory type block
> ----------------------------------------------------------------------------------------------------------------------
>
> Key: HBASE-10263
> URL: https://issues.apache.org/jira/browse/HBASE-10263
> Project: HBase
> Issue Type: Improvement
> Components: io
> Reporter: Feng Honghua
> Assignee: Feng Honghua
> Fix For: 0.98.0, 0.99.0
>
> Attachments: HBASE-10263-trunk_v0.patch, HBASE-10263-trunk_v1.patch,
> HBASE-10263-trunk_v2.patch
>
>
> 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.
--
This message was sent by Atlassian JIRA
(v6.1.5#6160)
