FISH-5723 Fixes WebappClassloader memory-leak issue by removing JAXRSResources classes from cache on shutdown event

[jGauravGupta]

Signed-off-by: Gaurav Gupta gaurav.gupta@payara.fish

[jansupol]

@jGauravGupta Thank you for the PR. I have two questions regarding the PR (perhaps I have a wrong understanding of @BeforeShutdown):

1. The cache purge is done on @BeforeShutdown, i.e. when Weld container is being shutdown. Does the Cache get not garbage collected when shutdown?
2. The CdiComponentProvider which holds the CdiComponentProviderRuntimeSpecifics is a CDI Extension, and Weld container keeps only a single instance of the class. (Well, there is another instance, not in Weld, but assumingly it has an empty Cache). Why do you purge the cache only for a single thread, instead of Cache.clear()?

[jGauravGupta]

Hello @jansupol ,

This issue is reproducible for both the Payara and Glassfish servers if the web application contains JAXRS resources.

Yes, the cache is not garbage collected by default on application un-deployment which holds the JAXRS resource classes reference of all deployed applications hence WebappClassloader is not garbage collected. @BeforeShutdown callback in the extension is invoked on the un-deployment of each application and removes the specific JAX-RS resource classes which belong to currently undeploying application classloader instead of 'Cache.clear()' (which will remove the cache for existing application).

[jansupol]

@jGauravGupta Thanks!