Timeline for BiasedLocking removal?

[daniel.daugherty at oracle.com]

JDK-8256425 Obsolete Biased Locking in JDK 18
https://bugs.openjdk.java.net/browse/JDK-8256425

On 5/11/21 9:50 AM, Roman Kennke wrote:
> Hi Hotspot devs,
>
> what is the timeline for removing BiasedLocking altogether? Or have we 
> even agreed that we are going to remove it?
>
> I am asking because this affects how I'd move forward with Lilliput. 
> If I can ignore BiasedLocking because it'd be removed in, say, JDK 18 
> anyway, then I believe I can come up with a relatively simple 
> implementation for 64bit header that should be possible to integrate 
> into JDK 18. That is, I put the (compressed) Klass* in the upper bits 
> of the header, also keep the hashcode in the header, and keep 
> everything else (locking, GC bits) as they are.
>
> With biased-locking, the Klass* would clash with the Thread* in the 
> upper bits. If we are not going to remove BiasedLocking anytime soon, 
> I would have to come up with a different plan.
>
> (Also, note that I expect the performance improvement of Lilliput to 
> outweight possible - and hopefully rare - biased-locking removal 
> regressions)
>
> WDYT?
>
> Cheers,
> Roman
>