Thread: Ancient Java program freezes when using java MainFunctionClass but runs in debugger after breakpoint

I am trying to help out a colleague who has a relatively old Java program (it last worked circa 2009).

I can run the program just fine on an old (circa 2007 MacBook running Java 1.5.0_13), and I decided to see if I could get it running on my current Mac with Java 21 (openjdk version "21" 2023-09-19). Good luck, right?

I found the main function in a class (`Sim`), and ran as follows:

java Sim

I got a splash screen and then the program freezes (well, button presses don't do anything).

I decided to see what jdb would do, and I got the same issue, UNTIL I tried breaking on main and then continuing -- and it worked! It was able to get past the initial screen. Here is a video that shows what is going on:

https://web.stanford.edu/~cgregg/would-be-gentleman-jdb.mov

But, I'm stuck. I don't understand why jdb would only get past the first screen after breaking on main, and I'd like to figure out if there is some incantation of `java` I can use to run it normally. Thanks for any insight!

Well, sometimes stumbling around works -- using `-Xint` to disable JIT and AOT did the trick:

java -Xint Sim