JDK 15 hidden classes & stack trace visibility

[Mandy Chung]

Hi Uwe,

It's a future enhancement to allow a class/method to request filtering 
from stack trace:
     https://bugs.openjdk.java.net/browse/JDK-8212620

This RFE should also take hidden classes into account.

Mandy

On 9/5/20 4:55 AM, Uwe Schindler wrote:
> Hi,
>
> I am doing a mockup for dynamically compiled scripts in Apache Lucene (later
> also painless scripting in elastcsearch), where I tried to use
> Lookup#defineHiddenClass (with default parameters, so weak and no nestmates
> - but: for painless scripts of Elasticsearch, nestmates will be great). It
> all looks great, as sometimes for every query a new class is generated.
>
> The current approach (Java 8, Java 11) uses a Classloader per script, which
> is mostly OK, but hidden classes would be better, especially under high load
> with many new classes. The problem I see is: The hidden class and their
> methods are also hidden from stack traces, so people neither get the script
> source code reference, nor they get the method, which was called at all.
>
> My question is: is it possible to mark such a hidden class in byte code or
> by a flag to defineHiddenClass() so it is "unhidden"? - I know you can do
> this by a command line option, but that's for developers and debugging only.
> In some cases, this is really wanted (like for scripting languages), but
> code still wants to use the better class unloading. If this is not possible,
> how about extending the Lookup.ClassOption enum (last parameter of
> defineHiddenClass), to also pass a flag to show them in stack traces?
>
> Uwe
>
> -----
> Uwe Schindler
> uschindler at apache.org
> ASF Member, Apache Lucene PMC / Committer
> Bremen, Germany
> https://lucene.apache.org/
>
>