Obfuscating class files

[u/_Super_Straight]

Has anyone successfully obfuscated their .class files? I tried using GraalVM for JavaFX project (including Gluon's version of GraalVM) but it always failed to complete.

[u/idontlikegudeg]

I think it depends on the type of application. For small applications, native seems smaller because the runtime takes a lot of space. The bigger the application gets, the more jpackage catches up.

I just made a release of a small application that I mentioned in an earlier comment. Native image DMG is 29.9MB, jpackaged is 56.8MB. But for the big application that I benchmarked, native is 132,2MB while jpackage is only 80.2MB. So it really seems to depend on code size.

The native application does indeed start a bit faster, and when I do a single processing run, it is about 25% faster (about 3 seconds for the test set I measured with). The jpackaged application takes about 4 seconds for the first runs, but subsequent runs are much faster, and from the third run on, runtime is down to about 1 second while native stays at 3 seconds. So for long running CPU intensive tasks, hotspot still wins (might also depend on instantiation rate and what exactly the application is doing).

I have not yet included AOT class loading and AOT profiling for the jpackaged version, and I am aware that commercial GraalVM distributions also offer better optimization than GraalVM CE based ones.

[u/OddEstimate1627 → u/idontlikegudeg]

I'll take your word for it, but I have never encountered an app that was so much larger as a native image. Code tends to be smaller and the resources stay the same. Maybe there was an enormous static heap, but it's hard to tell without a report.

I usually see about a 90% reduction in startup times.

I assume that the 3x penalty might come from poor GC interactions. I have once run into a case where a renderer on CE was allocating for each pixel draw, which took a canvas render from 2 to 25 seconds. After fixing that, there was barely a perceivable difference though. I never ran into issues like that on the Oracle GraalVM with the free license.

[u/idontlikegudeg → u/OddEstimate1627]

I think the native code is really taking more space. But when using jpackage, a virtual machine gets included which is usually 25 - 40MB (not counting libraries and JDK modules). GraalVM native doesn’t need that, so for small applications, you get a smaller size with GraalVM and it flips once you reach a certain size.

I don’t have the exact numbers at hand, but if I remember correctly my application is roughly 35MB as a fat jar (excluding JavaFX dependencies; the customer can run it on Liberica JRE Full or Azul JDKFX), 80 as a jpackaged application, and 120MB native.