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From Antonio Gomes Rodrigues <ra0...@gmail.com>
Subject Re: svn commit: r1654701 - /jmeter/trunk/src/core/org/apache/jmeter/util/ThreadLocalRandom.java
Date Tue, 03 Feb 2015 13:17:24 GMT
Hi,

In modern JVM it's useless because it remove dead code.

This technique is use in C/C++ in mechanical sympathy (to be friendly with
cpu cache to avoid to much context switch in it)

Antonio




2015-01-26 21:16 GMT+01:00 Philippe Mouawad <philippe.mouawad@gmail.com>:

> Hi,
> Thanks for infos.
>
> By the way I noticed netty had a variation of this class in their code
> which inits seed differently.
>
> Regards
>
>
>
> On Mon, Jan 26, 2015 at 7:28 AM, Felix Schumacher <
> felix.schumacher@internetallee.de> wrote:
>
> >
> >
> > Hi Phillipe.
> >
> > Am 25. Januar 2015 22:42:27 MEZ, schrieb Philippe Mouawad <
> > philippe.mouawad@gmail.com>:
> > >Hi Felix,
> > >Reverted , can you explain to me this ? I don't see these fields used,
> > >are
> > >they through reflection ?
> >
> > They are not used. Neither directly nor indirectly. They are used as
> > padding to prevent cache issues on hardware level. You will find more
> > information when you search the Internet for "ThreadLocalRandom padding".
> >
> > It might be, that we don't need the padding on modern jvms, but if we
> > assumed to have those, we would not need the copy of the class either :)
> >
> > That is why I opt for keeping the "useless" variables.
> >
> > Regards
> > Felix
> > >
> > >Thanks
> > >
> > >On Sun, Jan 25, 2015 at 10:30 PM, Felix Schumacher <
> > >felix.schumacher@internetallee.de> wrote:
> > >
> > >>
> > >>
> > >> Am 25. Januar 2015 21:35:48 MEZ, schrieb pmouawad@apache.org:
> > >> >Author: pmouawad
> > >> >Date: Sun Jan 25 20:35:48 2015
> > >> >New Revision: 1654701
> > >> >
> > >> >URL: http://svn.apache.org/r1654701
> > >> >Log:
> > >> >Remove unused fields
> > >> >
> > >> >Modified:
> > >> >
> > >jmeter/trunk/src/core/org/apache/jmeter/util/ThreadLocalRandom.java
> > >> >
> > >> >Modified:
> > >> >jmeter/trunk/src/core/org/apache/jmeter/util/ThreadLocalRandom.java
> > >> >URL:
> > >> >
> > >>
> > >
> >
> http://svn.apache.org/viewvc/jmeter/trunk/src/core/org/apache/jmeter/util/ThreadLocalRandom.java?rev=1654701&r1=1654700&r2=1654701&view=diff
> > >>
> > >>
> >
> >
> >>==============================================================================
> > >> >---
> > >jmeter/trunk/src/core/org/apache/jmeter/util/ThreadLocalRandom.java
> > >> >(original)
> > >> >+++
> > >jmeter/trunk/src/core/org/apache/jmeter/util/ThreadLocalRandom.java
> > >> >Sun Jan 25 20:35:48 2015
> > >> >@@ -54,11 +54,6 @@ public class ThreadLocalRandom extends R
> > >> >      */
> > >> >     boolean initialized;
> > >> >
> > >> >-    // Padding to help avoid memory contention among seed updates
> > >in
> > >> >-    // different TLRs in the common case that they are located near
> > >> >-    // each other.
> > >> >-    private long pad0, pad1, pad2, pad3, pad4, pad5, pad6, pad7;
> > >>
> > >> Given the comment above the fields, I would not remove those padding
> > >> fields.
> > >>
> > >> Regards
> > >> Felix
> > >> >-
> > >> >     /**
> > >> >      * The actual ThreadLocal
> > >> >      */
> > >>
> > >>
> >
> >
>
>
> --
> Cordialement.
> Philippe Mouawad.
>

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