Hi, I am using 34 GB heap and my use case is also Read oriented. I also do writes with MR. :) Yesterday, under decent load i got pauses of 30-40 secs. Still, the RS were not using the full 34 GB. I am thinking of doing some more tuning as i expect the read load to increase.
Here is my GC setting for JDK6: -XX:NewSize=200m -XX:MaxNewSize=400m -XX:+UseParNewGC -XX:+UseConcMarkSweepGC -XX:CMSInitiatingOccupancyFraction=70 -verbose:gc ~Anil On Tue, Jul 9, 2013 at 8:12 AM, Bryan Beaudreault <bbeaudrea...@hubspot.com>wrote: > I see from the blog post that it is java7. The question still stands > regarding using that with hbase, considering the open jira > https://issues.apache.org/jira/browse/HBASE-5261 > > > On Tue, Jul 9, 2013 at 11:03 AM, Bryan Beaudreault < > bbeaudrea...@hubspot.com > > wrote: > > > @Otis, are you guys running G1GC with java6 or java7? From what I'm > > reading it seems to be more stable with better performance in java7, but > I > > also believe java7 is not officially supported by apache hadoop or hbase > > yet. I'm wondering if many people are using java7 for hbase without > issue > > despite the lack of support. > > > > > > On Tue, Jul 9, 2013 at 1:52 AM, Azuryy Yu <azury...@gmail.com> wrote: > > > >> This is my HBASE GC options of CMS, it does work well. > >> > >> XX:+DisableExplicitGC -XX:+UseCompressedOops -XX:PermSize=160m > >> -XX:MaxPermSize=160m -XX:GCTimeRatio=19 -XX:SoftRefLRUPolicyMSPerMB=0 > >> -XX:SurvivorRatio=2 -XX:MaxTenuringThreshold=1 > -XX:+UseFastAccessorMethods > >> -XX:+UseParNewGC -XX:+UseConcMarkSweepGC -XX:+CMSParallelRemarkEnabled > >> -XX:CMSInitiatingOccupancyFraction=70 -XX:+UseCMSCompactAtFullCollection > >> -XX:CMSFullGCsBeforeCompaction=0 -XX:+CMSClassUnloadingEnabled > >> -XX:CMSMaxAbortablePrecleanTime=300 -XX:+CMSScavengeBeforeRemark > >> > >> > >> > >> On Tue, Jul 9, 2013 at 1:12 PM, Otis Gospodnetic < > >> otis.gospodne...@gmail.com > >> > wrote: > >> > >> > Hi, > >> > > >> > Check > >> http://blog.sematext.com/2013/06/24/g1-cms-java-garbage-collector/ > >> > > >> > Those graphs show RegionServer before and after switch to G1. The > >> > dashboard screenshot further below shows CMS (top row) vs. G1 (bottom > >> > row). After those tests we ended up switching to G1 across the whole > >> > cluster and haven't had issues or major pauses since.... knock on > >> > keyboard. > >> > > >> > Otis > >> > -- > >> > Solr & ElasticSearch Support -- http://sematext.com/ > >> > Performance Monitoring -- http://sematext.com/spm > >> > > >> > > >> > > >> > On Mon, Jul 8, 2013 at 2:56 PM, Stack <st...@duboce.net> wrote: > >> > > On Mon, Jul 8, 2013 at 11:09 AM, Suraj Varma <svarma...@gmail.com> > >> > wrote: > >> > > > >> > >> Hello: > >> > >> We have an HBase cluster with region servers running on 8GB heap > size > >> > with > >> > >> a 0.6 block cache (it is a read heavy cluster, with bursty write > >> traffic > >> > >> via MR jobs). (version: hbase-0.94.6.1) > >> > >> > >> > >> During HBaseCon, while speaking to a few attendees, I heard some > >> folks > >> > were > >> > >> running region servers as high as 24GB and some others in the 16GB > >> > range. > >> > >> > >> > >> So - question: Are there any special GC recommendations (tuning > >> > parameters, > >> > >> flags, etc) that folks who run at these large heaps can recommend > >> while > >> > >> moving up from an 8GB heap? i.e. for 16GB and for 24GB RS heaps > ... ? > >> > >> > >> > >> I'm especially concerned about long pauses causing zk session > >> timeouts > >> > and > >> > >> consequent RS shutdowns. Our boxes do have a lot of RAM and we are > >> > >> exploring how we can use more of it for the cluster while > maintaining > >> > >> overall stability. > >> > >> > >> > >> Also - if there are clusters running multiple region servers per > >> host, > >> > I'd > >> > >> be very interested to know what RS heap sizes those are being run > at > >> ... > >> > >> and whether this was chosen as an alternative to running a single > RS > >> > with > >> > >> large heap. > >> > >> > >> > >> (I know I'll have to test the GC stuff out on my cluster and for my > >> > >> workloads anyway ... but just trying to get a feel of what sort of > >> > tuning > >> > >> options had to be used to have a stable HBase cluster with 16 or > >> 24GB RS > >> > >> heaps). > >> > >> > >> > > > >> > > > >> > > You hit full GC in this 8G heap Suraj? Can you try running one > >> server at > >> > > 24G to see how it does (with GC logging enabled so you can watch it > >> over > >> > > time)? On one hand, more heap may make it so you avoid full GC -- > if > >> you > >> > > are hitting them now at 8G -- because application has more head > room. > >> On > >> > > other hand, yes, if a full GC hits, it will be gone for > proportionally > >> > > longer than for your 8G heap. > >> > > > >> > > St.Ack > >> > > >> > > > > > -- Thanks & Regards, Anil Gupta
