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From Allen Wittenauer ...@apache.org>
Subject Re: Hadoop Java Versions
Date Wed, 22 Jun 2011 20:49:58 GMT

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. :)


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