Thanks Tim, that's good to know. I had been sticking with the 32 bit JVM for the same reason as Darren. Now I will try out the 64 bit ones.
Mark Murphy
STAR BASE Consulting, Inc.
mmurphy@xxxxxxxxxxxxxxx
-----"Tim Rowe" <timmr@xxxxxxxxxx> wrote: -----
To: java400-l@xxxxxxxxxxxx
From: "Tim Rowe" <timmr@xxxxxxxxxx>
Date: 03/25/2016 09:06AM
Cc: java400-l@xxxxxxxxxxxx
Subject: Re: JVM 1.8 64 vs 32 bit
Greetings, The recommendation to switch to a 32bit JVM back then was a
performance statement. 32 bit is half the size of 64 bit when is comes to
code path length ( roughly) so the 32 bit was just plain faster then the
64 bit. In Java6 this problem was mostly corrected. The Java guys added
a feature where conceptually they would only access things in a 32bit
manner until the heap size reached a size too large for the 32bit jvm, and
then it would switch magically to the 64 bit reference method. This
feature basically made the performance problem go away.
Today, with the machines and memory, not sure there is a lot of value for
the 32 bit jvm. I would recommend just using the 64 bit version. The
classic version of Java was only 64 bit, and I would not be surprised if
in the future the 32bit jvm want away.
Thanks Tim
Tim Rowe, timmr@xxxxxxxxxx
Business Architect Application Development & Systems Management for IBM i
IBM i Development Lab, Rochester, MN
(507) 253-6191 (Tie) 553-6191
http://www-03.ibm.com/systems/power/software/i/are/index.html
----- Original message -----
From: Darren Strong <darren@xxxxxxxxx>
Sent by: "JAVA400-L" <java400-l-bounces@xxxxxxxxxxxx>
To: java400-l@xxxxxxxxxxxx
Cc:
Subject: JVM 1.8 64 vs 32 bit
Date: Thu, Mar 24, 2016 2:43 PM
We use the JVM pretty heavily to generate HSSF Spreadsheets. Max heap
size
is 2GB. We also use java for a little Websphere stuff. Some years ago,
the general recommendation was to switch from the "classic JVM" which
was
64 bit, and to use the 32 bit J9 VM. Is that still true today? Is
there
an advantage or disadvantage to asking for the 64 bit J9 VM now?
Current setup with 64 bit:
java -version
java version "1.8.0"
Java(TM) SE Runtime Environment (build pap6480sr2-20151023_01(SR2))
IBM J9 VM (build 2.8, JRE 1.8.0 OS/400 ppc64-64 Compressed References
jvmap6480sr2-20151023_01_cr (JIT enabled, AOT enabled)
___________________________________
Darren Strong
Programmer/Analyst
Group Dekko, Inc.
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