About the issue of lock downgrade

David Holmes david.holmes at oracle.com
Mon Jul 1 23:15:41 UTC 2019

Hi Zhuo,

On 2/07/2019 1:36 am, zhuo chen wrote:
> Dear All
> Please help me, I have a question, from this article
> http://openjdk.java.net/jeps/8183909. Why is the weight lock here
> downgraded to lightweight, is there any benefit to doing this? Why not
> directly downgrade to a bias lock? Thank you for answering my question.Very
> looking forward to reply.

To get to monitor inflation biased-locking for an object has to have 
been revoked at some point. Once the bias has been revoked for an 
instance we do not allow it to be re-biased again. Biased-locking 
assumes only a single thread will lock a particular instance, so once we 
have shown that is not the case we drop biased-locking out of the picture.


>   Thank you guys
>   zhuo

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