Metaspace leak during indexing

[mbien]

Apache NetBeans version

Apache NetBeans 27 latest release candidate

What happened

A smoke test which I run during each release which opens all ~800 NB modules and lets NB index them found a potential classloader leak. (but I don't think this is a regression)

Metaspace grows during indexing, closing projects or GC does not free it afterwards.

looks like this once all projects indexed:

setting -J-Djava.source.aptutils.disable.classloader.cache=true does seem to help and GC appears to free resources again, but this might be only part of the story.

Language / Project Type / NetBeans Component

No response

How to reproduce

set -e

# opens all netbeans modules as code scanner smoke test

# 1) build netbeans and change netbeans project JDK to "default"
# 2) run script in netbeans project

NB="/path/to/extracted/zip"
JDK="/home/mbien/dev/java/jdk-25-ea_b32"

OPEN=$(find -maxdepth 2 -mindepth 2 -type d\
 -not -path "./.git*"\
 -not -path "./nbbuild/*"\
 -not -path "./dist/*"\
 -not -path "./ide/xml.core"\
 -not -path "./nbi/*" | sort | xargs)

#-J-Djava.source.aptutils.disable.classloader.cache=true

FLAGS="-J-Dorg.netbeans.modules.parsing.impl.indexing.LogContext\$EventType.PATH.treshold=20"

"$NB/bin/netbeans" --userdir /tmp/nbusr$$ --jdkhome $JDK $FLAGS $OPEN

Did this work correctly in an earlier version?

No / Don't know

Operating System

linux

JDK

25

Apache NetBeans packaging

Apache NetBeans binary zip

Anything else

No response

Are you willing to submit a pull request?

Maybe but not soon

[wilx]

I took a look and it seems this is just the soft references of the APTUtils.ClassLoaderRef doing what they are supposed to do. With lower Xmx (I tried 1536g) many of them get GC'd.