Calling dynamically defined method throws Java::JavaLang::NullPointerException or returns nil without executing method body

The line of code in question confuses me. It should not cause NPE unless something is seriously misconfigured in the JVM.

Here's the line of code:

UnsafeFactory.getUnsafe().throwException(throwable);

UnsafeFactory should be using a piece of code we generate in our build called GeneratedUnsafe. You should be able to find that in the jruby.jar file.

This is the second report I've had of this problem, so I don't doubt that it's real.

Are you able to build JRuby? If so, you could check out the jruby-1_6 branch and modify src/org/jruby/util/unsafe/UnsafeFactory.java setting the static DEBUG field to true. That would print out what's happening in there at startup; I assume we'll see an exception trace.

I thought I had my basis covered (wrapped up the state of app, deps and environment which manifested the issue) but I seem not to be able to reproduce the NPE issue anymore. Debugger seems not to be the trigger factor, even though I previously had a situation where commenting out debugger line made the NPE disappear.

The other part (the call not executing the method body) still is there.

I will still try to dig deeper. Suggestions are welcome.

Cloned JRuby, checked out jruby-1_6, set DEBUG=true, compiled and used the compiled JRuby to run the app. I did not get an exception trace (at least no to STDOUT or STDERR) or anything else different from what the published 1.6.7 does.

I ran into the NPE again. Now it only appears when exiting the console. With that homebrewn 1.6.7 having previously mentioned DEBUG=true it looks like this

java.lang.NoClassDefFoundError: Could not initialize class org.jruby.util.unsafe.UnsafeFactory
	at org.jruby.ast.RescueNode.interpretWithJavaExceptions(RescueNode.java:138)
	at org.jruby.ast.RescueNode.interpret(RescueNode.java:110)
	at org.jruby.ast.BeginNode.interpret(BeginNode.java:83)
	at org.jruby.ast.NewlineNode.interpret(NewlineNode.java:104)
	at org.jruby.evaluator.ASTInterpreter.INTERPRET_BLOCK(ASTInterpreter.java:111)
	at org.jruby.runtime.InterpretedBlock.evalBlockBody(InterpretedBlock.java:374)
	at org.jruby.runtime.InterpretedBlock.yield(InterpretedBlock.java:295)
	at org.jruby.runtime.InterpretedBlock.yieldSpecific(InterpretedBlock.java:229)
	at org.jruby.runtime.Block.yieldSpecific(Block.java:99)
	at org.jruby.RubyKernel.loop(RubyKernel.java:1410)

Complete trace
http://pastie.org/private/j4embn5nhrrjnvckqssma

I had already lost my hopes of reproducing but then it appeared again. This is a full reproduction of the NPE issue as it appeared before and using debug-enabled JRuby build: http://pastie.org/private/s3ogftmt0ykusuvtyus4fg

I expect this is fixed now. The exception-handling logic has been rewritten for JRuby 1.7 to just raise the original error. Most of the lines in these traces no longer match up.

If it's possible to reproduce, feel free to reopen.