CFV: New Project: CRaC

Anton Kozlov akozlov at
Thu Aug 5 20:06:57 UTC 2021

On 8/5/21 6:42 PM, Andrew Haley wrote:
> An API to notify Java programs about checkpoint and restore events
> seems to me like a weird place to start such a project: it
> concentrates on the "how" but not the "what" or the "why".

Why and what are still to reduce start-up/warm-up and save the state, to avoid
doing same computations again and again on both Java lang level and JVM level
doing JIT compilations.

> This project proposal starts with an existing proof-of-concept
> implementation. Andrew Dinn's point, I believe, was that solving the
> snapshot-and-restore problem in a way that is compatible with the Java
> Specification requires thinking about a lot of other things as well.
> In order for the API to be meaningful and portable we'd have to
> specify a lot of things about what happens when. I don't think that
> such an API could be a part of Java before these deep questions were
> addressed, as they must be for Project Leyden.

The checkpoint/restore concept does not require that big changes to the Java
lang.  Two (or more) phases of the Java application life-cycle are implicit.
The execution of a Java program is the same, but it may just pause for a while.
It's much different from compile-time/run-time separation for static images.


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