Re: How to guess the memory consumption of a Java object?

From:
Lew <lew@lewscanon.com>
Newsgroups:
comp.lang.java.programmer
Date:
Tue, 11 Sep 2007 09:55:17 -0400
Message-ID:
<YaadnY2TWsnbA3vbnZ2dnUVZ_iydnZ2d@comcast.com>
kcwong wrote:

On Sep 11, 4:38 pm, Ulrich Scholz <d...@thispla.net> wrote:

I guess that's a hard question: How to guess the memory consumption of
a Java object? Probably, that depends on the Java virtual machine and
on the operating system.

Lets first assume no inheritance and simple data types only. Maybe
there's a number for that.

Thanks,

Ulrich


Besides the other links already posted, let me point you to the Java
Specialists Newsletter, issue 142: http://www.javaspecialists.eu/archive/Issue142.html

Check out the other newsletters while you're there... some are pretty
fun to read or experiment with.


Roedy's is the better link. The nobilitas.com link leaves out a lot, like
that the size of an object can vary during runtime and even reduce to zero.

Roedy's doesn't mention that either, but it hints at it when it points out,

A JVM is free to store data any way it pleases internally, big or little endian, with any amount of padding or overhead, though primitives must behave as if they had the official sizes.


What neither link mentions is the influence of run-time optimization.

--
Lew

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