I was surprised the figures were as different as they are. I appreciate Romain's feedback - I suspect we won't see dramatic performance increases, but it certainly doesn't do us any harm, so I'll merge this in. Thanks for the patch!
Jon On Mon, Nov 26, 2018 at 2:40 PM Romain Manni-Bucau <rmannibu...@gmail.com> wrote: > +0 (this is only for error cases as far as i saw and a few concatenations > so you don't see the diff in practise + the compiler is able to optimize it > and even replace string builder when relevant these days) > > Romain Manni-Bucau > @rmannibucau <https://twitter.com/rmannibucau> | Blog > <https://rmannibucau.metawerx.net/> | Old Blog > <http://rmannibucau.wordpress.com> | Github < > https://github.com/rmannibucau> | > LinkedIn <https://www.linkedin.com/in/rmannibucau> | Book > < > https://www.packtpub.com/application-development/java-ee-8-high-performance > > > > > Le lun. 26 nov. 2018 à 15:38, Daniel Cunha <daniels...@apache.org> a > écrit : > > > Wowww! > > > > Nice catch Otávio! > > That is really a good improvement! > > > > Em seg, 26 de nov de 2018 às 10:47, Otávio Gonçalves de Santana < > > osant...@tomitribe.com> escreveu: > > > > > The reason to prefer StringBuilder is that both + and concat create a > new > > > object every time you call them (provided the right-hand side argument > is > > > not empty). This can quickly add up to a lot of objects, almost all of > > > which are completely unnecessary. > > > > > > public class Main{ > > > public static void main(String[] args) > > > { > > > long now = System.currentTimeMillis(); > > > slow(); > > > System.out.println("slow elapsed " + > > > (System.currentTimeMillis() - now) + " ms"); > > > > > > now = System.currentTimeMillis(); > > > fast(); > > > System.out.println("fast elapsed " + > > > (System.currentTimeMillis() - now) + " ms"); > > > } > > > > > > private static void fast() > > > { > > > StringBuilder s = new StringBuilder(); > > > for(int i=0;i<100000;i++) > > > s.append("*"); > > > } > > > > > > private static void slow() > > > { > > > String s = ""; > > > for(int i=0;i<100000;i++) > > > s+="*"; > > > } > > > } > > > > > > > > > - slow elapsed 11741 ms > > > - fast elapsed 7 ms > > > > > > Also, this PR avoids unnecessary call in StringBuilder > > > Ref: https://github.com/apache/tomee/pull/219 > > > > > > > > > -- > > Daniel "soro" Cunha > > https://twitter.com/dvlc_ > > >
