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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. -- This message is automatically generated by JIRA. - You can reply to this email to add a comment to the issue online.