I found the discussion on getInstance method had incurred performance degradation https://issues.apache.org/jira/browse/BCEL-186 .
>From the JIRA: > This feature could return as a pluggable cache if someone wants to provide a patch I'll think about the approach. Regards, Tomo On Thu, May 2, 2019 at 1:22 PM Gary Gregory <garydgreg...@gmail.com> wrote: > On Thu, May 2, 2019 at 10:59 AM Tomo Suzuki <suzt...@google.com.invalid> > wrote: > > > Gary, > > I didn't find ConstantUtf8.getCachedInstance > > < > https://github.com/apache/commons-bcel/blob/master/src/main/java/org/apache/bcel/classfile/ConstantUtf8.java#L94 > > > > is used in BCEL (latest 6.3.1). I tried my custom ConstantUtf8 > modification > > to leverage getCachedInstance method and it worked well: > > > > Before > > > > Without getCachedInstance, my tool created 2,6 million ConstantUtf8 > > instances (before failing OutOfMemoryError: GC overhead limit exceeded) > to > > check ~200 jar files > > [image: 2644k_constantutf8_without_getCachedInstance.png] > > > > > > After > > > > With getCachedInstance, my tool created just 0.6 million ConstantUtf8 > > instances. It didn't throw the OutOfMemoryError. > > [image: 621k_constantutf8_with_getCachedInstance.png] > > > > My modification was to use getCachedInstance for > > ConstantUtf8.getInstance(DataInput) > > < > https://github.com/apache/commons-bcel/blob/master/src/main/java/org/apache/bcel/classfile/ConstantUtf8.java#L123 > > > > . > > > > > > Do you know why ConstantUtf8.getCachedInstance is unused? > > > > I do not. > > Gary > > > > > > Regards, > > Tomo > > > > > > > > On Wed, May 1, 2019 at 7:02 PM Gary Gregory <garydgreg...@gmail.com> > > wrote: > > > >> On Wed, May 1, 2019 at 6:37 PM Tomo Suzuki <suzt...@google.com.invalid> > >> wrote: > >> > >> > Gary, > >> > That’s right. I missed it. I think I just need to find a way to > leverage > >> > the getCachedInstance method. Thank you for quick response. > >> > > >> > >> YW. Please let us know your outcome. > >> > >> Gary > >> > >> > >> > > >> > On Wed, May 1, 2019 at 18:00 Gary Gregory <garydgreg...@gmail.com> > >> wrote: > >> > > >> > > Why not use getCachedInstance() ? > >> > > > >> > > Gary > >> > > > >> > > On Wed, May 1, 2019 at 5:20 PM Tomo Suzuki > <suzt...@google.com.invalid > >> > > >> > > wrote: > >> > > > >> > > > Hi BCEL developers, > >> > > > > >> > > > We use BCEL library to inspect Java class. Thank you for the great > >> > > library. > >> > > > > >> > > > When our tool checks classes in ~200 jar files, it creates more > >> than 2 > >> > > > million BCEL ConstantUtf8 instances. I suspect many of them share > >> the > >> > > same > >> > > > values such as "java.lang.String". > >> > > > > >> > > > [image: many_constant_utf8.png] > >> > > > > >> > > > Given this observation, I got an idea to to reuse ConstantUtf8 > with > >> > same > >> > > > value to save memory footprint. Because ConstantUtf8 is constant, > >> > sharing > >> > > > the instances across classes should not cause a problem. Note that > >> BCEL > >> > > is > >> > > > not designed thread-safe (doc > >> > > > <https://commons.apache.org/proper/commons-bcel/faq.html>). > >> > > > > >> > > > If this is a good idea, I'm thinking to make a pull request around > >> > BCEL's > >> > > > ConstantUtf8.getInstance method: > >> > > > > >> > > > > >> > > > >> > > >> > https://github.com/apache/commons-bcel/blob/master/src/main/java/org/apache/bcel/classfile/ConstantUtf8.java#L116 > >> > > > > >> > > > Does anybody have any thought? > >> > > > > >> > > > -- > >> > > > Regards, > >> > > > Tomo > >> > > > > >> > > > >> > -- > >> > Regards, > >> > Tomo > >> > > >> > > > > > > -- > > Regards, > > Tomo > > > -- Regards, Tomo
