Hello,
Just a little update on my test.
I added a clear and gc before each Map instanciation and results are
different:
- HashMapput:645
- ConcurrentHashMapput:832
- ConcurrentReaderHashMapput:620
- HashMap get:17
- ConcurrentHashMap get:32
- ConcurrentReaderHashMap get:60
So it kind of closes the debate, sorry for disturbance.
Regards
Philippe
public class TestMap {
public static void main(String[] args) {
StopWatch timer = new StopWatch();
Map map = new HashMap();
testPut(timer, map, "HashMap");
timer.reset();
map.clear();
System.gc();
map = new ConcurrentHashMap();
testPut(timer, map, "ConcurrentHashMap");
timer.reset();
map.clear();
System.gc();
map = new ConcurrentReaderHashMap();
testPut(timer, map, "ConcurrentReaderHashMap");
timer.reset();
map.clear();
System.gc();
map = new HashMap();
testGet(timer, map, "HashMap");
timer.reset();
map.clear();
System.gc();
map = new ConcurrentHashMap();
testGet(timer, map, "ConcurrentHashMap");
timer.reset();
map.clear();
System.gc();
map = new ConcurrentReaderHashMap();
testGet(timer, map, "ConcurrentReaderHashMap");
timer.reset();
}
/**
* @param timer
*/
private static void testGet(StopWatch timer, Map map, String type) {
timer.start();
for (int i = 0; i < 1000000; i++) {
map.get(i);
}
timer.stop();
System.out.println(type+" get:"+timer.getTime());
}
/**
* @param timer
*/
private static void testPut(StopWatch timer, Map map, String type) {
timer.start();
for (int i = 0; i < 1000000; i++) {
map.put(i,i);
}
timer.stop();
System.out.println(type+"put:"+timer.getTime());
}
Regards
Philippe
On Mon, Oct 3, 2011 at 1:37 PM, sebb <seb...@gmail.com> wrote:
> On 3 October 2011 12:15, Rainer Jung <rainer.j...@kippdata.de> wrote:
> > On 02.10.2011 23:17, Philippe Mouawad wrote:
> >> Ok, hope we can do the same.
> >
> > See https://issues.apache.org/jira/browse/XMLBEANS-447
> >
> > We are not the only people, who doubt it's correct to include that class
> ...
> >
> > There was also a discussion some time ago in another ASF project,
> > because the Sun license which is cited by Doug Lea has a "no use in
> > nuclear facilities clause", which make it non-usable as an Open Source
> > license.
> >
> > It looks like we are stuck here.
>
> Yes, apart from the binary option which brings in lots of unneeded code.
>
> > And the mentioning of the Harmony class in the above cited issue is a
> > red herring. Diffing it with the JDK 5 standard ConcurrentHashMap shows
> > little difference, so I doubt it will be much faster (though I didn't
> > inspect the delta in detail).
>
> I think the Harmony class was only mentioned as a means of supporting
> Java 1.4, not as an alternative faster implementation.
>
> >> I must say I don't understand why ConcurrentReaderHashMap is not in JDK.
> >
> > There's a discussion list for JSR166 (the concurrency stuff lead by Doug
> > Lea) mentioned on the JSR 166 page maintained by Doug Lea. So maybe you
> > can post a technical question there (what's the right class that solve
> > the following problem ... and doesn't have sun licensing restrictions).
> >
> > Regards,
> >
> > Rainer
> >
> >
> > ---------------------------------------------------------------------
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> >
> >
>
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>
--
Cordialement.
Philippe Mouawad.
