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From Todd Lipcon <t...@cloudera.com>
Subject Re: ANN: The third hbase 0.94.0 release candidate is available for download
Date Mon, 14 May 2012 15:17:56 GMT
On Mon, May 14, 2012 at 8:15 AM, lars hofhansl <lhofhansl@yahoo.com> wrote:
> It's default off. I'd say we just say it's an experimental feature in the release notes.

+1 for calling it experimental in notes and docs, and not removing it.
Replication was in an experimental state for quite some time, too, and
we didn't rip that out - I think shipping things off-by-default with
clear labeling is one of the best ways to sand down rough edges.

>
>
> Are you saying we should have another RC?
> There was other stuff that went into 0.94 after I cut the RC, so that would potentially
need to stabilize if I cut a new RC now.
>
> -- Lars
>
> ________________________________
> From: Ted Yu <yuzhihong@gmail.com>
> To: dev@hbase.apache.org
> Sent: Monday, May 14, 2012 7:17 AM
> Subject: Re: ANN: The third hbase 0.94.0 release candidate is available for download
>
> Thanks for sharing this information, Ramkrishna.
>
> Dictionary WAL compression makes replication not functional - see details
> in https://issues.apache.org/jira/browse/HBASE-5778
>
> I would vote for the removal of Dictionary WAL compression until we make it
> more robust and consuming much less memory.
>
> On Mon, May 14, 2012 at 6:59 AM, Ramkrishna.S.Vasudevan <
> ramkrishna.vasudevan@huawei.com> wrote:
>
>> Hi
>>
>> One small observation after giving +1 on the RC.
>> The WAL compression feature causes OOME and causes Full GC.
>>
>> The problem is, if we have 1500 regions and I need to create
>> recovered.edits
>> for each of the region (I don’t have much data in the regions (~300MB)).
>> Now when I try to build the dictionary there is a Node object getting
>> created.
>> Each node object occupies 32 bytes.
>> We have 5 such dictionaries.
>>
>> Initially we create indexToNodes array and its size is 32767.
>>
>> So now we have 32*5*32767 = ~5MB.
>>
>> Now I have 1500 regions.
>>
>> So 5MB*1500 = ~7GB.(Excluding actual data).  This seems to a very high
>> initial memory foot print and this never allows me to split the logs and I
>> am not able to make the cluster up at all.
>>
>> Our configured heap size was 8GB, tested in 3 node cluster with 5000
>> regions, very less data( 1GB in hdfs cluster including replication), some
>> small data is spread evenly across all regions.
>>
>> The formula is 32(Node object size)*5(No of dictionary)*32767(no of node
>> objects)*noofregions.
>>
>> I think this initial memory needs to be documented (documentation should do
>> for now)or has to be fixed with some workarounds.
>>
>> So pls give your thoughts on this.
>>
>> Regards
>> Ram
>>
>>
>>
>>
>> > -----Original Message-----
>> > From: Ramkrishna.S.Vasudevan [mailto:ramkrishna.vasudevan@huawei.com]
>> > Sent: Monday, May 14, 2012 11:48 AM
>> > To: dev@hbase.apache.org; 'lars hofhansl'
>> > Subject: RE: ANN: The third hbase 0.94.0 release candidate is available
>> > for download
>> >
>> > Hi
>> > We (it includes the test team here) 0.94 RC and carried out various
>> > operations on it.
>> > Puts, Scans, and all the restart scenarios (using kill -9 also).  Even
>> > the
>> > encoding stuffs were tested and carried out our basic test scenarios.
>> > Seems
>> > to work fine.
>> >
>> > Did not test rolling restart with 0.92. By this week we may try to do
>> > some
>> > performance comparison with 0.92.
>> > Also Lars and I agreed for a point release too.
>> > So I am +1 on the RC.
>> >
>> > Regards
>> > Ram
>> >
>> > > -----Original Message-----
>> > > From: lars hofhansl [mailto:lhofhansl@yahoo.com]
>> > > Sent: Sunday, May 13, 2012 10:53 PM
>> > > To: dev@hbase.apache.org
>> > > Subject: Re: ANN: The third hbase 0.94.0 release candidate is
>> > available
>> > > for download
>> > >
>> > > OK, I'll change my tactic :)
>> > >
>> > > If there are no -1's by Wed, May 16th, I'll release RC4 as 0.94.0.
>> > >
>> > > -- Lars
>> > >
>> > >
>> > >
>> > > ----- Original Message -----
>> > > From: Stack <stack@duboce.net>
>> > > To: lars hofhansl <lhofhansl@yahoo.com>
>> > > Cc: "dev@hbase.apache.org" <dev@hbase.apache.org>
>> > > Sent: Friday, May 11, 2012 10:39 PM
>> > > Subject: Re: ANN: The third hbase 0.94.0 release candidate is
>> > available
>> > > for download
>> > >
>> > > On Fri, May 11, 2012 at 10:26 PM, lars hofhansl <lhofhansl@yahoo.com>
>> > > wrote:
>> > > > Thanks Stack.
>> > > >
>> > > > So that's two +1 (mine doesn't count I guess). And no -1.
>> > >
>> > > Why doesn't yours count?  Usually the RMs does, if they +1 it.  So,
>> > > that'd be 3x+1 + a non-binding +1.
>> > >
>> > > > I talked to Ram offline, and we'll fix HBase with Hadoop 2.0.0 in
a
>> > > 0.94 point release.
>> > > >
>> > > > I would like to see a few more +1's before I declare this the
>> > > official 0.94.0 release.
>> > > >
>> > >
>> > > You might be waiting a while (smile).  Fellas seem to be busy...
>> > >
>> > > Good on you Lars,
>> > > St.Ack
>>
>>



-- 
Todd Lipcon
Software Engineer, Cloudera

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