Re: Cost of creating objects?

From:
lipska the kat <"nospam at neversurrender dot co dot uk">
Newsgroups:
comp.lang.java.programmer
Date:
Wed, 07 Aug 2013 19:24:37 +0100
Message-ID:
<4r-dnQ2D5r51DZ_PnZ2dnUVZ8q-dnZ2d@bt.com>
On 07/08/13 19:19, lipska the kat wrote:

On 07/08/13 08:44, Sebastian wrote:

@Override
public int compare(AttrValue o1, AttrValue o2)
{
   Long ts1 = o1.getEffectiveSequenceNumber(); // ??
   Long ts2 = o2.getEffectiveSequenceNumber(); // ??
   return ts1.compareTo(ts2);
}

Would you expect a measureable impact of creating these
variables ts1, ts2, instead of "inlining" the calls to
getEffectiveSequenceNumber(). (Using JDK 6?)

How can I reason about this things, probably influenced by
JIT, without doing actually measurements, say as part of a
code inspection?


Have you heard of a profiler?

A few years ago I used one to investigate an application running on
Weblogic application server, the results were eye opening.

I seem to remember the company I was working for handed over a large wad
of cash to get a couple of licences for a commercial product ... can't
remember what it was called unfortunately.

Googling 'java profiler' today returns the usual plethora of hits and I
expect the game has moved on since I last used one, there also appear to
be a bunch of free ones out there.

If you want to reason about this stuff then it might pay you to have a
look at your application with a profiler, you will almost certainly
learn something to help you in your endeavors.


Apparently there is a tool included in later JDKs

http://docs.oracle.com/javase/6/docs/technotes/guides/visualvm/

Amazing

lipska

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