Charles Oliver Nutter wrote:
>  In general we have inserted synchronization code only where it really 
>  appears to be necessary to maintain the integrity of data structures. 
>  That means that in some cases, you need to be mindful of code actually 
>  running in parallel against e.g. arrays, hashes, strings, and so on. But 
>  we do want to reduce the possibility of a Java exception, so I'll 
>  investigate a bit.

I did find a few threading bugs in JRuby, and I'm working on them now. 
Most of them seem specific to Enumerator...

- Charlie