Support for AOT, AOTCache for faster netbeans startup

[ivan-velikanov]

Description

JDK25 comes with stable feature additions such as -XX:AOTCacheOutput and -XX:AOTCache however currently netbeans doesn't seem to support these options by configuring the netbeans.conf file. If set netbeans launcher throws an error in the console logs saying Unknown options.
Is it possible to have these enabled?
Thank you

Use case/motivation

Will make netbeans start faster

Related issues

No response

Are you willing to submit a pull request?

No

[matthiasblaesing]

This is not an issue of NetBeans. The JDK must support the option and the description indicates to me, that you did nothing to configure JDK25 to be used. The FOAN installers bundle JDK 24, so it is not surprising, that this does not work.

[ivan-velikanov]

It is the simple zip version of jdk25 and I set the jdk_home in the netbeans.conf file. I guess i will also specify --jdkhome and retry (just for testing atleast)

[mbien]

AOT caches break most applications which do anything related to dynamic module loading. I am also somewhat skeptical that it would do something for NB, since most work IDEs do is highly use case specific - NB itself starts in ~3s or so if nothing else has to be opened too.

https://openjdk.org/jeps/483 see "risks and assumptions", esp the first two points are showstoppers

[neilcsmith-net]

Also see "non-goals" - "It is not a goal to cache classes that are loaded by user-defined class loaders." That's NetBeans out for a start! 😄

At least one of the aims of this JEP is also partly covered by the bootstrap startup cache as far as I know.

[mbien]

btw the classloader limitation is essentially a prefix rule. The training run classpath must be a prefix of the production run classpath. Good enough for services etc, but its not gonna launch NB more than once ;)

[ivan-velikanov]

Yes netbeans is not slow, but for a long time, I had hopes of having a AOT netbeans that would open as fast as notepad/notepad++ ...

[ivan-velikanov]

Even with zulu jdk25 for AOT it says Unknown option -XX:AOTCacheOutput=nb.aot , after sometime i realized i did not prefix -J- after that it worked, but I did not feel a significant increase in speed, it just felt fast. It already load quiet decently so I am unable to say. There were several warning messages related to aot ...

[35.818s][warning][aot] Preload Warning: Verification failed for org.netbeans.modules.javahelp.JavaHelp
[36.614s][warning][aot] Skipping jdk/internal/jrtfs/JrtFileSystemProvider: Duplicated unregistered class
[36.615s][warning][aot] Skipping jdk/internal/jrtfs/JrtFileSystem: Duplicated unregistered class
[36.615s][warning][aot] Skipping jdk/internal/jrtfs/JrtPath: Duplicated unregistered class
[36.615s][warning][aot] Skipping jdk/internal/jrtfs/JrtFileStore: Duplicated unregistered class
[36.616s][warning][aot] Skipping jdk/internal/jrtfs/SystemImage$1: Duplicated unregistered class
[36.616s][warning][aot] Skipping jdk/internal/jrtfs/ExplodedImage: Duplicated unregistered class
[36.616s][warning][aot] Skipping jdk/internal/jrtfs/SystemImage$2: Duplicated unregistered class
[36.617s][warning][aot] Skipping jdk/internal/jimage/ImageReader: Duplicated unregistered class
... it goes on

The AOT file was ~150 MB

(Edited)

[lahodaj]

I think I concur with @mbien and @neilcsmith-net that this is likely not help NB very much (because of the ClassLoaders, and possibly also other things). But, the "Unknown option" error is confusing me, given this is a java launcher option. Are you prefixing the options with -J (so that the java launcher gets them)? I tried this:

./netbeans --jdkhome ~/tools/jdk/jdk-25/ --userdir /tmp/nbuser.aot -J-XX:AOTMode=record -J-XX:AOTConfiguration=app.aotconf
./netbeans --jdkhome ~/tools/jdk/jdk-25/ --userdir /tmp/nbuser.aot -J-XX:AOTMode=create -J-XX:AOTConfiguration=app.aotconf -J-XX:AOTCache=app.aot
./netbeans --jdkhome ~/tools/jdk/jdk-25/ --userdir /tmp/nbuser.aot -J-XX:AOTCache=app.aot

And it seems to run. I am not saying it is faster, just that it runs.

[ivan-velikanov]

As i mentioned, I forgot suffix -J- in the config file ... and my experience is also same ... it runs I am not able to tell if it is faster, I am not performing any benchmark tests. Plus there are error messages like :

[0.079s][error][aot] An error has occurred while processing the AOT cache. Run with -Xlog:aot for details.
[0.079s][error][aot] Mismatched values for property jdk.module.addmods: runtime jdk.jshell dump time java.instrument,jdk.jshell
[0.080s][error][aot] Disabling optimized module handling
[0.081s][error][aot] AOT cache has aot-linked classes. It cannot be used when archived full module graph is not used.
[0.092s][error][aot] Unable to map shared spaces

[lkishalmi]

Using NetBeans with AOT enabled since JDK24. The startup time improves 1-3 seconds on my computer, that's not really a significant amount of time when the IDE opens in about 11 secs anyway.

NetBeans has its class-cache mechanism, that's already cut the second time start time. I guess if we would not have that mechanism, we might be able to reduce the IDE startup time by half with AOT cache.

So for whoever interested it can be used/tested (It's kind of nice on my Rasberry Pi400), tho I do not think it is worth for the general audience at the moment.

[OndroMih]

I agree. I have the same experience with AOT on Java 25. It reduces startup time for me from 9 seconds to 6 seconds, about 30%. But I had issues when I upgraded Netbeans and forgot to regenerated the AOT cache file: #9392 (comment)

So it's not for general public but yes, it can be configured in netbeans.conf. This is what I have there:

netbeans_default_options="-J-XX:AOTCache=/ide.aot

and if your system Java is older than 25:

netbeans_jdkhome="path/to/java25"

To generate the AOT cache file, run netbeans with:

netbeans --jdkhome /path/to/java25 -J-XX:AOTCacheOutput=/ide.aot

[mbien]

nb 30 itself should start in 2.5-3s on nvme. Most time is spent in project loading after that.

aot on jdk 26 can reduce this to about 1.6-2s. But project loading still needs to happen.

make sure the startup run you use for image generation is a realistic startup run. (first launch isnt)

https://github.com/mbien/nb-launcher here is a toy which makes experimenting with it easier. --aot enables leyden, launcher itself can be compiled to native.

[ivan-velikanov]

Thanks @mbien , this experiment definitely has a use case. Right now I have 2 things (i) notepad++ for quick edits (ii) netbeans ide for projects. A faster launcher might reduce the motivation to use notepad++ or something else especially when it is involves code.

[mbien]

just to clarify: the launcher isnt faster. I wrote it to make release testing easier for me. --aot is just there for convenience - the same can be achieved by setting the JVM flags the usual way.

NB30 also got two small startup improvements #9307, #9303. There is more in the queue but not sure when i will be able to finish it up.