RFR: 8280041: Retry loop issues in java.io.ClassCache [v3]

[Aleksey Shipilev]

On Wed, 19 Jan 2022 10:42:02 GMT, Peter Levart <plevart at openjdk.org> wrote:

> So, this patch is fine for making ClassCache more robust as a re-usable component inside JDK (checking for non-null return of computeValue). The 2nd change, that apparently shields against unbounded accumulation of garbage, might not be enough in the sense that when garbage accumulated without bounds, there would be not progress. So before the patch, we would at least get an OOME and the loop would end. Now the loop could spin indefinitely. So perhaps we must rather prevent this from happening in some other way... I have an idea. Stay tuned.

I think playing the catch-up race with GC (which we will eventually win, IMO) is better than obscure OOME. Note this matches other places we do the weak-reference loops, for example in `MethodType`: https://github.com/openjdk/jdk/blob/master/src/java.base/share/classes/java/lang/invoke/MethodType.java#L1390-L1401

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PR: https://git.openjdk.java.net/jdk/pull/7092