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? 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
