AppCDS, DynamicCDS, Leyden and JRuby

[Charles Oliver Nutter]

Alexey Shipilev directed me toward the -Xlog flag to silence the CDS
output, which seems to work pretty well. I wish I could direct this to
/dev/null, though!

-Xlog:cds=off -Xlog:cds=warning:file=jsa.log

This would also silence the stale JSA warning. My second question stands,
though: why can't I incrementally add to the JSA by starting up with it AND
dumping a new one at the end?

On Wed, Feb 12, 2025 at 12:37 PM Charles Oliver Nutter <headius at headius.com>
wrote:

> Hello friends, I'm revisiting CDS-related stuff in JRuby today! Claes R.
> suggested I direct my CDS questions here, since this list represents the
> future of that work.
>
> We are keenly awaiting the new AOTCache stuff but for now I'm looking
> primarily at AppCDS or DynamicCDS given the upcoming JRuby 10 baseline JDK
> level of 21.
>
> So, I have a JRuby launcher script that already can detect and use a jsa
> generated for JRuby into the install location. I'm adding a flag to run
> -XX:ArchiveClassesAtExit and have a few questions:
>
> * OMG that warning output... is there any way to capture that to a file
> without redirecting the whole process?
> * Why is it not possible to boot with one JSA and then dump a new JSA at
> the end? It complains if I use both SharedArchiveFile and
> ArchiveClassesAtExit in the same command line.
> * Is there any way to verify if the JSA will be usable (not stale, etc)
> without parsing stderr output from the failed attempt to use it?
>
> Basically I'm trying to make this a hidden automatic feature in the JRuby
> launcher: if the JSA doesn't exist, generate and use it; if it's stale
> because JRuby or JDK changed, regenerate and use it. That's hard to do if
> it's spitting warnings at my users.
>
> *Charles Oliver Nutter*
> *Architect and Technologist*
> Headius Enterprises
> https://www.headius.com
> headius at headius.com
>
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