RFR: 8258588: MD5 MessageDigest in java.util.UUID should be cached

[PROgrm_JARvis]

On Fri, 18 Dec 2020 14:55:08 GMT, Claes Redestad <redestad at openjdk.org> wrote:

> A more general issue is that this patch assumes the `MessageDigest` object returned is statically shareable, which implies it being stateless and thread-safe.
> 
> This doesn't seem to be the case. See [MD5.java](https://github.com/openjdk/jdk/blob/master/src/java.base/share/classes/sun/security/provider/MD5.java) and the [DigestBase.java](https://github.com/openjdk/jdk/blob/master/src/java.base/share/classes/sun/security/provider/DigestBase.java) base class, which both have mutating buffers for doing the digest.

Wow, this is interesting. In this case I will check if there is a way to implement a thread-safe mechanism there. Will report here once there is some result.

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PR: https://git.openjdk.java.net/jdk/pull/1821