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Re: HashSet keeps all nonidentical equal objects in memory

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On Jul 20, 11:43 am, Frederik <landcglo...@gmail.com> wrote:
> Hi,
>
> I've been doing java programming for over 10 years, but now I've
> encoutered a phenomenon that I wasn't aware of at all.
> I had an application in which I have a HashSet<String>. I added a lot
> of different String objects to this HashSet, but many of the String
> objects are equal to each other. Now, after a while my application ran
> out of memory, even with -Xmx1500M. This happened when there were only
> about 7000 different Strings in the set! I didn't understand this,
> until I started adding the "intern()" of every String object to the
> set instead of the original String object. Now the program needs
> virtually no memory anymore.
> There is only one explanation: before I used "intern()", ALL the
> different String objects, even the ones that are equal, were kept in
> memory by the HashSet! No matter how strange it sounds. I was
> wondering, does anybody have an explanation as to why this is the case?

I did another experiment in which I generated a large file with the
same string on every line, and then wrote a program that reads in the
file and adds every line String to a HashSet. With that, I cannot
reproduce the problem. So in my other code I must be doing something
very specific which triggers this problem. I don't know what it is,
but never mind.

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HashSet keeps all nonidentical equal objects in memory Frederik <landcglobal@gmail.com> - 2011-07-20 02:43 -0700
  Re: HashSet keeps all nonidentical equal objects in memory Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-07-20 07:30 -0400
  Re: HashSet keeps all nonidentical equal objects in memory Frederik <landcglobal@gmail.com> - 2011-07-20 04:09 -0700
    Re: HashSet keeps all nonidentical equal objects in memory markspace <-@.> - 2011-07-20 08:22 -0700
  Re: HashSet keeps all nonidentical equal objects in memory Robert Klemme <shortcutter@googlemail.com> - 2011-07-20 08:38 -0700
    Re: HashSet keeps all nonidentical equal objects in memory lewbloch <lewbloch@gmail.com> - 2011-07-20 09:31 -0700

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