Re: After deserialization program occupies about 66% more RAM

From:
Robert Klemme <shortcutter@googlemail.com>
Newsgroups:
comp.lang.java.programmer
Date:
Tue, 19 Sep 2006 14:56:41 +0200
Message-ID:
<4na7o9F9j2bcU1@individual.net>
On 19.09.2006 14:32, Paul Davis wrote:

Changing the code to actually show the internal reference shows that
the deserialized version produces the same results as the one before
serialization.


What exactly do you mean by "same results"? Of course string values
remain the same. I was talking about internal representation (i.e. the
char arrays used). You cannot see that with a Java program alone, you
need a memory profiler or a debugger to actually see those instances and
determine which are identical and which not.

Also, using String.intern() completely changes the semantics memory
wise. Of course the comparison returns true because it is actually the
same instance (and thus also the same char[] internally). My point was
that if strings are constructed from each other then serializing and
deserializing can seriously affect memory usage because of the changed
internal representation (no more sharing of char[]).

Using intern() might also be a bad idea for changing data because
interned strings will continuously increase the VM's memory. This might
not be an issue for short lived applications but it certainly can be for
long running apps.

Regards

    robert

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