| Re: [january-dev] clone() vs System.arraycopy |
Well, once we move to a JIPP then we can integrate the micro benchmarking and end these “optimisations” ;-) Well, at least for one JVM.
Peter
From: january-dev-bounces@eclipse.
org [mailto:january-dev-bounces@eclipse.org ] On Behalf Of Matthew Gerring
Sent: 17 October 2017 11:49
To: Filik, Jacob (DLSLtd,RAL,LSCI) <Jacob.Filik@xxxxxxxxxxxxx>
Cc: january developer discussions <january-dev@xxxxxxxxxxx>
Subject: Re: [january-dev] clone() vs System.arraycopy
Thanks for reading that. He also says:
"Oops, it seems that once the array becomes longer, the performance of the two is almost equal! Infact, the cloning seems marginally faster. Aren't you glad that you have not changed all your code yet?"
:)
On 17 October 2017 at 11:45, <Jacob.Filik@xxxxxxxxxxxxx> wrote:
I have only skimmed the article but he concludes:
This leads me to conclude that the only reason why Paul's test seemed so much faster was because he picked a byte[] size that was small enough that the actual copying was dwarfed by the two
ifstatements. Using clone() for copying arrays is less code and the performance difference is, as we saw, only significant for tiny arrays. I think that in future I will rather use clone() than System.arrayCopy().
From: january-dev-bounces@eclipse.
org [mailto:january-dev-bounces@eclipse.org ] On Behalf Of Matthew Gerring
Sent: 17 October 2017 11:35
To: january developer discussions <january-dev@xxxxxxxxxxx>
Subject: [january-dev] clone() vs System.arraycopy
Hello,
January uses clone() quite a bit when duplicating large primitive arrays. For one of many instances see FloatDataset:
odata = data = "">
However System.arraycopy is ~5x faster according to:
Are there any plans to migrate from clone to arraycopy? Or do I have to submit a PR to do that? I might ask one of the team here to submit that change if you agree, please let me know you thoughts.
Matt
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