Hey @ratnikov, this issue bisects to the introduction of LibrarySearcher in 613673a. Here's some extra information in case it helps:

This is the command generated by this test for 1.9 (1.8 is similar):

echo 1,2,3 | "bin/jruby" --1.9 -J-Dfoo=bar -v -T3 -d -Ku -a -n -Ihello -C .. -F, -e 'puts $VERBOSE, $SAFE, $DEBUG, Encoding.default_external, $F.join(59.chr), $LOAD_PATH.join(44.chr), Dir.pwd, Java::java::lang::System.getProperty(:foo.to_s)'

Without 613673a (for instance, I checked out 1.7.13), this generates a number of warnings (about it not being 1.8), a couple of exceptions (side note: not sure if it's significant, but the 1.8 case does not have these exceptions), and some reasonable output.

With 613673a, this outputs many, many errors and hangs the test for some reason that isn't jumping out at me....

Hopefully that's enough to help you zero straight in on the issue... let me know if there's more I can do to help.

Oops. @ratnikov: I typoed your username in my comment. Fixed now, but I'm mentioning you again to make sure you're notified.

Fun! Thanks for tracking this, will look at it.

The -d flag is what causes it, by forcing to print all the class loading exceptions.

The reason for class loading exceptions is because it attempts to find a 'Service' for a library probably for .rb suffixed, and not just 'extension' suffixes.

More specifically, I guess prior to LibrarySearcher the process for loading via 'load' is slightly different than require and the exception was triggered only then. Now that they're uniform, we attempt to load XXXService even requires, causing much more ClassNotFoundExceptions and logging in debug mode.

I guess there are a couple of options here:

1. Revert to the old behavior that XXXService only works with Kernel#load and not with Kernel#require. That would require the code to track whether the call came via load or require and skip the findServiceLibrary call if it's require.
2. Maybe perform findServiceLibrary iff we're loading an 'extension' type of suffix, so .jar or .so and not .rb. I'm not really sure whether we currently depend on that behavior.
3. Avoid rendering the classNotFound exception when lookup fails.

@enebo Any input? :)

Why does it hang?

since 1.7.x has EOLed .. let's call this one a day, shall we 🍂