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From Bryan Beaudreault <bbeaudrea...@hubspot.com>
Subject Re: suggestion for how eliminate memory problem in heavy-write hbase region server
Date Mon, 28 Apr 2014 00:45:03 GMT
Keep in mind the math for heap.  Memstore is 40%, and that is divided
across all regions for a RS.  With 2GB, that's under 30mb per region
assuming well distributed writes.

Are your regionservers starved for CPU?  Either way, I'd try the java7 G1
GC on one regionserver and report back.  We run with 25GB heaps and never
have long pauses, so 16GB should be fine with enough CPU.


On Sun, Apr 27, 2014 at 8:27 PM, Henry Hung <YTHung1@winbond.com> wrote:

> @Vladimir:
>
> My total region count is 330 right now, but I expect the number will
> surpass 1000 at the end of this year.
> Although current system is heavy-write, but I expect it to be also a read
> intense system, because I want to do a lot of data analysis in the future.
>
> About memory allocation, I assign 16 GB heap memory just because I have so
> many RAM space left over to allocate (each node has 32GB RAM installed).
> I never really thought that 2GB heap will be enough, but will give it a
> shot.
>
> Best regards,
> Henry
>
> -----Original Message-----
> From: Vladimir Rodionov [mailto:vrodionov@carrieriq.com]
> Sent: Saturday, April 26, 2014 1:48 AM
> To: user@hbase.apache.org
> Subject: RE: suggestion for how eliminate memory problem in heavy-write
> hbase region server
>
> I am just wondering why do you need large heaps on write - heavy cluster?
> How many regions per RS do you have? Usually large heaps need for read
> intensive applications to keep blocks in a cache, but now we have option to
> keep these blocks off heap (at least since 0.96) With MemSLAB for MemStore
> enabled you need 2MB (by default) per region, this is what you need to take
> into account first. Even 1000 regions won't eat more than 2GB of heap.
>
> Best regards,
> Vladimir Rodionov
> Principal Platform Engineer
> Carrier IQ, www.carrieriq.com
> e-mail: vrodionov@carrieriq.com
>
> ________________________________________
> From: Ted Yu [yuzhihong@gmail.com]
> Sent: Friday, April 25, 2014 9:47 AM
> To: user@hbase.apache.org
> Subject: Re: suggestion for how eliminate memory problem in heavy-write
> hbase region server
>
> Henry:
> Please also take a look at the following thread:
>
>
> http://search-hadoop.com/m/51M4jeDMyy1/GC+recommendations+for+large+Region+Server+heaps&subj=RE+GC+recommendations+for+large+Region+Server+heaps
>
>
> On Thu, Apr 24, 2014 at 11:17 PM, Mikhail Antonov <olorinbant@gmail.com
> >wrote:
>
> > Henry,
> >
> > http://blog.ragozin.info/2011/10/java-cg-hotspots-cms-and-heap.html -
> > that may give some insights.
> >
> > -Mikhail
> >
> >
> > 2014-04-24 23:07 GMT-07:00 Henry Hung <YTHung1@winbond.com>:
> >
> > > Dear All,
> > >
> > > My current hbase environment is heavy write cluster with constant
> > > 2000+ insert rows / second spread to 10 region servers.
> > > Each day I also need to do data deletion, and that will add a lot of
> > > IO
> > to
> > > the cluster.
> > >
> > > The problem is sometimes after a week, one of the region server will
> > crash
> > > because
> > > 2014-04-10T10:17:47.200+0800: 1281486.956: [GC 1281486.956: [ParNew
> > > (promotion failed): 235959K->235959K(235968K), 0.0836790
> > secs]1281487.040:
> > > [CMS2014-04-10T10:21:14.957+0800: 1281694.712: [CMS-concurrent-sweep:
> > > 267.111/279.155 secs] [Times: user=334.79 sys=14.38, real=279.11
> > > secs] (concurrent mode failure): 13961950K->6802914K(16515072K),
> > > 209.9436660 secs] 14186496K->6802914K(16751040K), [CMS Perm :
> > 42864K->42859K(71816K)],
> > > 210.0274680 secs] [Times: user=210.18 sys=0.01, real=209.99 secs]
> > >
> > > I look into the gc log and usually find some information about CMS
> > > concurrent sweep that took a very long time to complete, such as:
> > > 2014-04-10T10:15:56.929+0800: 1281376.684: [CMS-concurrent-sweep:
> > > 48.834/58.027 secs] [Times: user=101.52 sys=11.82, real=58.02 secs]
> > >
> > > I do a lot of google-ing and already read the Todd Lipcon avoiding
> > > full GC, or other blogs that sometimes tells me how to set jvm flags
> > > such as
> > > this:
> > > -XX:+UseParNewGC
> > > -XX:CMSInitiatingOccupancyFraction=70
> > > -Xmn256m
> > > -Xmx16384m
> > > -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:+UseCMSCompactAtFullCollection
> > > -XX:CMSFullGCsBeforeCompaction=0
> > > -XX:+CMSClassUnloadingEnabled
> > > -XX:CMSMaxAbortablePrecleanTime=300
> > > -XX:+CMSScavengeBeforeRemark
> > >
> > > But alas, the problem still exist.
> > >
> > > I also know that java 1.7 has a new G1GC that probably can be used
> > > to fix this problem, but I don't know if hbase 0.96 is ready to use it?
> > >
> > > I would really appreciate it if someone out there can share one or
> > > two things about jvm configuration to achieve a more stable region
> server.
> > >
> > > Best regards,
> > > Henry
> > >
> > > ________________________________
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> >
> >
> >
> > --
> > Thanks,
> > Michael Antonov
> >
>
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