RFR: 8263562: Checking if proxy_klass_head is still lambda_proxy_is_available

[Yi Yang]

On Mon, 15 Mar 2021 02:17:36 GMT, Yi Yang <yyang at openjdk.org> wrote:

> The `Shared Lambda Dictionary` section in the result of SharedLambdaDictionaryPrinter will mix normal klasses with lambda proxy klasses. Using the following commands can reproduce it:
> 
> Proc1: `./jshell`
> Proc2: `jcmd <proc1> VM.systemdictionary -verbose`
> 
> When all archived lambda proxy classes are used, proxy_klass_head(in RunTimeLambdaProxyClassInfo) is still referring to an instance klass that is no longer lambda_proxy_is_available, and its next_link will be set by classloader to link another normal class. Simply checking if proxy_klass_head is lambda_proxy_is_available can solve this problem.
> 
> Best regards,
> Yang

Furthermore, I think we should clear proxy_klass_head when it becomes no longer lambda_proxy_is_available. Any further accesses will be illegal. Just IMHO, I will hold this only if you think it's useful.

-------------

PR: https://git.openjdk.java.net/jdk/pull/3001