RFR: 8272113: Build compare script fails with differences in classlist

[Thomas Schatzl]

On Sat, 7 Aug 2021 07:25:01 GMT, Ioi Lam <iklam at openjdk.org> wrote:

> The CDS classlist is generated with the `-XX:DumpLoadedClassList` option, which writes the name of the classes as they are being loaded. Since class loading order is affected by thread switching, the classes may appear in a non-deterministic order.
> 
> Previously, the build compare script would sort the classlist before comparing. Since https://bugs.openjdk.java.net/browse/JDK-8272113, each class in the classlist has a new ID, so even after sorting, the contents would differ:
> 
> 
> $ diff classlist.1 classlist.2
> 207,208c207,208
> < jdk/internal/misc/VM id: 201
> < jdk/internal/util/SystemProps id: 202
> ---
>> jdk/internal/misc/VM id: 202
>> jdk/internal/util/SystemProps id: 201
> 
> 
> The fix is to strip the id before doing the file comparison.
> 
> Tested with:
> 
> `mach5 remote-build -b linux-aarch64-cmp-baseline,macosx-x64-cmp-baseline,linux-x64-cmp-baseline,linux-arm32-open-cmp-baseline,windows-x64-cmp-baseline`

Lgtm.

-------------

Marked as reviewed by tschatzl (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/5041