Optimize loading of multirelease JAR files in a WAR

[OndroMih]

This issue is copied from piranhacloud/piranha#3669. Check out that issue for more information and comments from investigation of possible solutions.

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Hi, I noticed that when a WAR file contains a multirelease JAR file, it takes an extremely long time to deploy even a simple application.

Here's an example application:
myapp.war.zip (source code here:
jsf-hello-world.zip

To reproduce, just run the Piranha Web Profile distribution with the app, like this:

java -jar piranha-dist-webprofile-24.2.0.jar --war-file myapp.war

I took a few thread dumps during deployment:
threaddumps.zip

On my computer, it took 96 seconds (1.5 minutes) to deploy the reproducer app (actually, deployment failed, but that's because of a classloading issue in my app with javax/jakarta package prefix, that's not very relevant in this case)

[OndroMih]

Hi, @InocencioC, would you still like to work on this? I can now assign you this issue if you want, although you can raise PRs at any time, even if the issue is not assigned to you.

[InocencioC]

@OndroMih,

I had a quick look at the beginning, but I couldn’t identify the cause of the problem. I think it’s a good idea to assign this task to me, as I’ve never looked into this part before. This way I can investigate it more thoroughly and see how we can optimize the loading.

[OndroMih]

Sure, @InocencioC. Take your time and investigate. If you have doubts, let me know.

[InocencioC]

Hi @OndroMih ,
It hasn’t been long since our last exchange, but I’ve been quite busy with work.
I’ve now started digging deeper into the issue and will share my findings as I progress. I’ll come back with updates in the next few days. Thanks for your patience!