RFR: 8272417: ZGC: fastdebug build crashes when printing ClassLoaderData

[Stefan Karlsson]

On Fri, 13 Aug 2021 07:14:51 GMT, Tongbao Zhang <github.com+1866174+tbzhang at openjdk.org> wrote:

> Following test fails on fastdebug build with the options: "-XX:+UseZGC -XX:+VerifyAfterGC -Xlog:gc*=trace". It crashes on the unknown claim value of the ClassLoaderData
> 
> public class A {
>     public static void main(String... args) {
>         System.gc();
>     }
> }
> 
> The unknown claim value  of the ClassLoaderData is "ClassLoaderData::_claim_other | ClassLoaderData::_claim_strong" which is introduced by the ZVerifyOopClosure. This patch clears the CLD's claimed marks after the ZGC verification

I mentioned in the bug report that this is not enough to correctly fix this bug. Could you fix the printing code instead?

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Changes requested by stefank (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/5107