RFR: 8265602: -XX:DumpLoadedClassList should support custom loaders [v2]

[Yumin Qi]

On Wed, 4 Aug 2021 06:33:03 GMT, Ioi Lam <iklam at openjdk.org> wrote:

>> Some applications load a lot of classes using custom loaders. This PR improves the start-up performance of these apps when using a "static" CDS archive:
>> 
>> Here are performance numbers for the Eclipse IDE:
>> 
>> 
>> Static Archive Before: 7.31 sec (classlist does not include custom loader classes)
>> Static Archive After:  6.49 sec (classlist includes custom loader classes)
>> Dynamic Archive:       6.62 sec
>
> Ioi Lam has updated the pull request incrementally with one additional commit since the last revision:
> 
>   @calvinccheung comments

Looks good!
One concern is that this patch works for custom class in a plain jar file, but won't work with if the class loader has its own way to load class from more complicated location like "fat" jar, is it correct?

test/hotspot/jtreg/runtime/cds/appcds/test-classes/DumpClassListApp.java line 2:

> 1: /*
> 2:  * Copyright (c) 2021, Oracle and/or its affiliates. All rights reserved.

Is this a new file?

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PR: https://git.openjdk.java.net/jdk/pull/4952