Scoped variables

Ron Pressler ron.pressler at
Mon Dec 3 18:24:30 UTC 2018

Hi Andrew.

Yes, scope variables are indeed orthogonal to fibers (although we would like to 
combine them with structured concurrency). 

Dean Long has started working on an early prototype, which he’ll present hopefully soon.
While scope locals are certainly superior to TLs from a programming perspective,
I’m not sure beating them on sheer performance would be so easy. But If you 
have some ideas on how to do that, they would be most welcome.


On December 3, 2018 at 4:49:47 PM, Andrew Haley (aph at wrote:

We discussed "scoped variables" as a possible fiber-oriented  
replacement for thread locals. I have some interest in this area, so I  
was wondering if anyone had started to work on this. If not, I'll  
volunteer to propose a design.  

These could also be useful even when fibers aren't being used: we'd  
want something more efficient than ThreadLocals, but that's a very low  
bar. So, please let me know.  

Andrew Haley  
Java Platform Lead Engineer  
Red Hat UK Ltd. <>  
EAC8 43EB D3EF DB98 CC77 2FAD A5CD 6035 332F A671  

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