Project Loom presentation at BangaloreJUG

Alan Bateman Alan.Bateman at
Sun Dec 15 20:34:58 UTC 2019

On 14/12/2019 11:34, Nawazish Khan wrote:
> Hi All,
> I would be speaking on Project Loom at BangaloreJUG which would be hosted
> at Oracle office on 21st December, 2019.
> Let me know if I could help by taking any survey or any other information
> which might be helpful to all of us as an input to the project Loom.
We don't have any prepared surveys but there are several areas where it 
would be useful to collect data.

In the current prototype, if a virtual thread parks (network I/O or 
locking operation) while holding a monitor then it pins the carrier 
thread. This is a quality-of-service rather than a correctness issue but 
it would be useful to get reaction to needing to change some (not all) 
code to use java.util.concurrent locks to workaround this limitation for 
the short term. If there are developers trying out the current repo in 
the meet-up then get them to run with -Djdk.tracePinnedThreads=full and 
see if the monitors usages would be easy or hard to change.

Thread locals. It would be useful to get data on whether developers are 
using TLs directly or not. We've looked at a lot of TL usages in 
libraries and frameworks but not applications as they aren't easy to get 
at. One of the topics being explored in this project is scope locals and 
it would be useful to get an idea how many of the TL usages could be 
replaced with scope locals.


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