Date: Fri, 12 Dec 2003 12:15:14 -0300 From: "Nicolas Gieczewski" <nicolas@nixsoftware.com> To: <freebsd-java@freebsd.org> Subject: Re: How's linux-ibm-jdk14 in the memory footprint department? Message-ID: <04d601c3c0c2$cfc357e0$0200a8c0@veggy.org> References: <2946E9F05C8DD511A7DC0002A5608CE4DB2026@gbchm201.exgb01.exch.eds.com>
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Many thanks to Thomas and Dan for their replies. The actual RSS has =
always been around 16 MB, but I was thinking the difference between VSZ =
and RES was going into the swap area. Obviously a lack of knowledge on =
memory management on my part. I'll have to read some stuff on this.
Thanks again,
Nick
----- Original Message -----=20
From: "Sparrevohn, Thomas" <thomas.sparrevohn@eds.com>
To: "'Dan Nelson'" <dnelson@allantgroup.com>; <freebsd-java@freebsd.org>
Sent: Friday, December 12, 2003 08:02
Subject: RE: How's linux-ibm-jdk14 in the memory footprint department?
Yes - I looked at It and it seems that while it uses a large address =
space the RSS stays around 21MB-41MB for j2ee as an example. There are a =
potential problem with the way it is done that would occur if a very =
large library was used. Has anybody looked at deferred loads?
-----Original Message-----
From: owner-freebsd-java@freebsd.org =
[mailto:owner-freebsd-java@freebsd.org] On Behalf Of Dan Nelson
Sent: 11 December 2003 23:41
To: freebsd-java@freebsd.org
Subject: Re: How's linux-ibm-jdk14 in the memory footprint department?
Nicolas Gieczewski wrote:
> Thanks for the suggestion. I could only get it down to about 152 MB
> with an initial heap size of 8 MB and a maximum size of 16 MB. I=20
> believe this is probably too small, though (actually, I have no idea,=20
> guess I'll have to see how often the GC is kicking in). Even though=20
> not all of the 152 MB (or 203 MB, for that matter) are in main memory=20
> at any given time, don't they become unavailable to the OS, anyway?=20
Definitely not. Note that java will mmap any .jar files you use, so=20
things like rt.jar will add 30MB to your process size right off the bat. =
Very little of it will actually get paged in from disk, though, and=20
what little does get paged in will be shared across all java processes.=20
I don't know where the rest of the 100 or so MB is going, but the most =
important thing to watch is the RSS value and whether you are swapping=20
or not. I did a simple test of running /usr/local/jdk1.4.2/bin/jar on a =
little file and pausing it so I could see the stats in top:
PID USERNAME PRI NICE SIZE RES STATE TIME WCPU CPU COMMAND
24511 dan 97 0 198M 7460K STOP 0:00 0.00% 0.00% jar
Note that the process space is almost 200MB, but really under 8MB is=20
being used. My guess is the extra space has something to do with=20
threads, or maybe a sparse array was allocated (like what rpc.statd =
does).
--=20
Dan Nelson
dnelson@allantgroup.com
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