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From Scott Carey <sc...@richrelevance.com>
Subject Re: Hadoop Java Versions
Date Thu, 23 Jun 2011 02:42:48 GMT


On 6/22/11 1:49 PM, "Allen Wittenauer" <aw@apache.org> wrote:

>
>On Jun 22, 2011, at 1:27 PM, Scott Carey wrote:
>
>> "Problems have been reported with Hadoop, the 64-bit JVM and Compressed
>> Object References (the -XX:+UseCompressedOops option), so use of that
>> option is discouraged."
>> 
>> I think the above is dated.  It also lacks critical information. What
>>JVM
>> and OS version was the problem seen?
>
>That is definitely dated.  Those were problems from 18 and 19.
>
>> 
>> CompressedOops had several issues prior to Jre 6u20, and a few minor
>>ones
>> were fixed in u21.  FWIW, I now exclusively use 64 bit w/ CompressedOops
>> for all Hadoop and non-Hadoop apps and have seen no issues.  It is the
>> default in 6u24 and 6u25 on a 64 bit JVM.
>
>	We use compressedoops on 21 every-so-often as well.
>
>	Feel free to edit that whole section. :)
>
>	Thanks!

Updated the CompressedOops section.

I am using 6u25 in production and have used 6u24 as well.  (64 bit
version, CentOS 5.5)
We usually roll out JVM's to a subset of nodes, then after a little
burn-in to the whole thing.  First on development / qa clusters (which are
just as busy as production, but smaller), then production.

>


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