case study of : vm_athrow_unhandled

Submitted by Trickkiste on Tue, 05/04/2004 - 18:30.

JNode-Core

hi,

can anyone please describe a case in which instead of the

public void uncaughtException(Thread t, Throwable e) from java.lang.ThreadGroup

the
vm_athrow_unhandled from vm.asm

is used?

thanks,

Andreas

P.S.: I know that the public void uncaughtException(Thread t, Throwable e) from java.lang.ThreadGroup
is some kind of backup mechanism, to handle unhandled Exceptions in threads of that group,
but in JNode I think there is Java code executed under this backupsystem or am I wrong?

A Case

Submitted by admin on Tue, 05/04/2004 - 19:42.

This native code is called when no handler is available in the java stack, which might be the case when:

The root (first created) thread throws an exception in the exception handler.
Something is seriously wrong in the VM implementation

Anyhow, it is not likely to happen anymore, but was a good development aid for the VM development itself.

PS. I think uncaughtException is not even called yet. This is a bug.

Ewout

a bug in what?

Submitted by Trickkiste on Tue, 05/04/2004 - 20:12.

Hi,
thanks for the info.

What do you mean with "This is a bug"? Or where is this bug?

Because in the The Java(TM) Virtual Machine Specification in chapter 2 Section 16 (Exceptions) it is defined to do the following :

If no catch clause handling an exception can be found, then the current thread (the thread that encountered the exception) is terminated, but only after all finally clauses have been executed and the method uncaughtException has been invoked for the ThreadGroup that is the parent of the current thread.

Andreas