[jira] Commented: (HBASE-3455) Heap fragmentation in region server

["Todd Lipcon (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-3455?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12984324#action_12984324 ] 

Todd Lipcon commented on HBASE-3455:
------------------------------------

For reference, the R commands I use to produce graphs look like:
{code}
library(ggplot2)
d <- read.table(file="/tmp/fls.txt", header=T)
qplot(time, value, data=melt(subset(d, time>122000&time<127000), c("time"), measure.vars=c("free_space", "max_chunk")), facets=variable~., geom="line")
{code}

And since JIRA screwed up formatting on those JVM options, repaste:
{noformat}
-XX:+PrintGCDetails -XX:+PrintGCDateStamps -XX:+PrintTenuringDistribution -verbose:gc
-Xloggc:$HBASE_HOME/logs/gc$(hostname)-hbase.log
-XX:PrintCMSStatistics=1 -XX:PrintFLSStatistics=1
{noformat}

> Heap fragmentation in region server
> -----------------------------------
>
>                 Key: HBASE-3455
>                 URL: https://issues.apache.org/jira/browse/HBASE-3455
>             Project: HBase
>          Issue Type: Brainstorming
>          Components: performance, regionserver
>            Reporter: Todd Lipcon
>            Priority: Critical
>         Attachments: HBasefragmentation.pdf, parse-fls-statistics.py
>
>
> Stop-the-world GC pauses have long been a problem in HBase. "Concurrent mode failures" can usually be tuned around by setting the initiating occupancy fraction low, but eventually the heap becomes fragmented and a promotion failure occurs.
> This JIRA is to do research/experiments about the heap fragmentation issue and possible solutions.

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