cassandra-commits mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "dan jatnieks (JIRA)" <j...@apache.org>
Subject [jira] [Comment Edited] (CASSANDRA-6357) Flush memtables to separate directory
Date Mon, 24 Mar 2014 21:20:57 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-6357?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13945705#comment-13945705
] 

dan jatnieks edited comment on CASSANDRA-6357 at 3/24/14 9:19 PM:
------------------------------------------------------------------

I can also go back and re-run 2.0 w/patch on the same machine used for 2.1 ... but that patch
isn't quite the same as the 2.1 code either...

I was wondering if changes to flushing and/or compaction in 2.1 already lessen the contention
that was present in 2.0?


was (Author: djatnieks):
I can also go back and re-run 2.0 w/patch on the same machine used for 2.1 ... but that patch
isn't quite the same as the 2.1 code either...

> Flush memtables to separate directory
> -------------------------------------
>
>                 Key: CASSANDRA-6357
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-6357
>             Project: Cassandra
>          Issue Type: New Feature
>          Components: Core
>            Reporter: Patrick McFadin
>            Assignee: Jonathan Ellis
>            Priority: Minor
>              Labels: performance
>             Fix For: 2.1 beta1
>
>         Attachments: 6357-v2.txt, 6357.txt, c6357-2.1-stress-write-adj-ops-sec.png, c6357-2.1-stress-write-latency-99th.png,
c6357-2.1-stress-write-latency-median.png, c6357-stress-write-latency-99th-1.png
>
>
> Flush writers are a critical element for keeping a node healthy. When several compactions
run on systems with low performing data directories, IO becomes a premium. Once the disk subsystem
is saturated, write IO is blocked which will cause flush writer threads to backup. Since memtables
are large blocks of memory in the JVM, too much blocking can cause excessive GC over time
degrading performance. In the worst case causing an OOM.
> Since compaction is running on the data directories. My proposal is to create a separate
directory for flushing memtables. Potentially we can use the same methodology of keeping the
commit log separate and minimize disk contention against the critical function of the flushwriter.




--
This message was sent by Atlassian JIRA
(v6.2#6252)

Mime
View raw message