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Date: Mon, 21 Jan 2013 23:06:37 +0100
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Subject: Re: Use ThreadLocalRandom instead of Random
From: Philippe Mouawad <philippe.mouawad@gmail.com>
To: dev@jmeter.apache.org
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On Mon, Jan 21, 2013 at 11:04 PM, sebb <sebbaz@gmail.com> wrote:

> On 21 January 2013 21:18, Philippe Mouawad <philippe.mouawad@gmail.com>
> wrote:
> > On Mon, Jan 21, 2013 at 10:03 PM, sebb <sebbaz@gmail.com> wrote:
> >
> >> On 21 January 2013 20:56, Philippe Mouawad <philippe.mouawad@gmail.com>
> >> wrote:
> >> > On Mon, Jan 21, 2013 at 9:45 PM, sebb <sebbaz@gmail.com> wrote:
> >> >
> >> >> On 21 January 2013 20:27, Philippe Mouawad <
> philippe.mouawad@gmail.com>
> >> >> wrote:
> >> >> > Hello Sebb,
> >> >> > My answers below.
> >> >> >
> >> >> > Regards
> >> >> > Philippe
> >> >> >
> >> >> > On Mon, Jan 21, 2013 at 6:22 PM, sebb <sebbaz@gmail.com> wrote:
> >> >> >
> >> >> >> On 21 January 2013 12:28, Philippe Mouawad <
> >> philippe.mouawad@gmail.com>
> >> >> >> wrote:
> >> >> >> > Hello,
> >> >> >> > Java 7 introduced ThreadLocalRandom which has much better
> >> performances
> >> >> >> than
> >> >> >> > using Random as static instance.
> >> >> >> > See:
> >> >> >> >
> >> >> >> >
> >> >> >>
> >> >>
> >>
> http://docs.oracle.com/javase/tutorial/essential/concurrency/threadlocalrandom.html
> >> >> >> >
> >> >> >>
> >> >>
> >>
> http://niklasschlimm.blogspot.fr/2012/01/java-7-how-to-write-really-fast-java.html
> >> >> >> >
> >> >> >> >
> >> >> >> > Implementation is here for Java6 but can we use it with Apache
> >> >> License ?:
> >> >> >> >
> >> >> >>
> >> >>
> >>
> https://github.com/codahale/metrics/blob/master/metrics-core/src/main/java/com/yammer/metrics/stats/ThreadLocalRandom.java
> >> >> >>
> >> >> >> That appears to be public domain.
> >> >> >> Not sure of whether that is allowable or not.
> >> >> >>
> >> >> >> >
> >> >> >> > Or should we migrate to Java 7 as Java6 will be soon EOL ?
> >> >> >>
> >> >> >> Is the performance of Random a significant problem for JMeter?
> >> >> >> Does it affect all tests? Or just some test elements?
> >> >> >> If not, then I don't think it's worth the effort.
> >> >> >>
> >> >> >
> >> >> > I will affect:
> >> >> > - RandomVariableConfig
> >> >> > - RandomController
> >> >> > - RandomTimer
> >> >>
> >> >> Yes, but I doubt these are used frequently.
> >> >>
> >> >
> >> > I agree
> >> >
> >> >>
> >> >> > - RegexpExtractor => Used a lot
> >> >> > - HtmlExtractor => Hope it will be :-)
> >> >> > - __regexFunction
> >> >> > - AnchorModifier
> >> >>
> >> >> But is the random option used frequently?
> >> >>
> >> > Well I must say I use it on almost every Test Plan I did these last
> years
> >> > :-)
> >> >
> >> > If random is still called even if not selected, then that should be
> >> >> fixed anyway.
> >> >>
> >> > No that's OK, it is called only if 0 is selected.
> >> >
> >> >>
> >> >> > So maybe we could at least impact:
> >> >> > - RegexpExtractor => Used a lot
> >> >> > - HtmlExtractor => Hope it will be :-)
> >> >> > - RandomController
> >> >>
> >> >> Yes, but will speeding up calls to Random affect a test run by much?
> >> >>
> >> >
> >> > Well with high number of threads I think it begins impacting.
> >> >
> >>
> >> Well I doubt it.
> >>
> >
> > Why ? I tend to trust Doug Lea and the blog I sent by a Java core
> > developer. Should we check this ? It takes time.
>
> I don't doubt that the new Random implementation is faster.
>
> However, whether that has a significant (measurable) impact on a test
> run is another matter.
>
> >>
> >> >
> >> >> e.g. by how much does using random RE slow down a sample test
> compared
> >> >> with using a fixed RE?
> >> >> Is it really significant?
> >> >>
> >> >
> >> > I didn't test but in my opinion, whenever we can improve core parts we
> >> > should.
> >>
> >> Yes, but in this case there are side effects, so the potential
> >> improvement needs to be demonstrated.
> >>
> >> What are the side effects ? Can you clarify ?
>
> Requiring Java 7.
> Or extra work on licensing.
>
> Who can help at Apache with licensing questions ?

> >
> >> > As I am not sure it will cost us a lot.
> >> > But if you have some other fields to improve in mind, let's work on
> it.
> >> >
> >> > You still didn't answer to my mail on logging framework replacement
> ;-)
> >>
> >> Post a reminder to the thread.
> >>
> >> Done.
> >
> >> >
> >> >
> >> >> >
> >> >> >>
> >> >> >> As to whether to require Java 7, I suspect Java 6 will still be
> used
> >> >> >> by many (especially businesses) until long after EOL (and remember
> >> >> >> users can pay to have longer support).
> >> >> >>
> >> >> >
> >> >> > I agree with you this policy applies for Application servers, but
> for
> >> >> tools
> >> >> > like JMeter I don't think it does. From my experience as a JMeter
> >> user,
> >> >> we
> >> >> > always were able to have a particular Java version installed.
> >> >>
> >> >> >>
> >> >> >> If a move to Java 7 would allow the use of new APIs that provide
> >> >> >> significant performance improvements then it might be worth doing.
> >> >> >> But we do need to be aware that requiring Java 7 as a minimum may
> >> well
> >> >> >> exclude some users.
> >> >> >>
> >> >> >
> >> >> > Same answer as before.
> >> >> > I think if we cannot use  ThreadLocalRandom as copy / paste in
> JMeter
> >> >> > source, it is worth thinking about moving to Java 7.
> >> >> > Who can help us on this license problem ?
> >> >> >
> >> >> >>
> >> >> >> > Regards
> >> >> >> > Philippe M.
> >> >> >>
> >> >> >
> >> >> >
> >> >> >
> >> >> > --
> >> >> > Cordialement.
> >> >> > Philippe Mouawad.
> >> >>
> >> >
> >> >
> >> >
> >> > --
> >> > Cordialement.
> >> > Philippe Mouawad.
> >>
> >
> >
> >
> > --
> > Cordialement.
> > Philippe Mouawad.
>


-- 
Cordialement.
Philippe Mouawad.

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