@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:[email protected]] Sent: Saturday, April 26, 2014 1:48 AM To: [email protected] 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: [email protected] ________________________________________ From: Ted Yu [[email protected]] Sent: Friday, April 25, 2014 9:47 AM To: [email protected] 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 <[email protected]>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 <[email protected]>: > > > 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 > > > > ________________________________ > > The privileged confidential information contained in this email is > > intended for use only by the addressees as indicated by the original > sender > > of this email. 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