RFR: 8253495: CDS generates non-deterministic output

[Thomas Stuefe]

On Fri, 11 Mar 2022 06:50:00 GMT, David Holmes <david.holmes at oracle.com> wrote:

> I can combine the tests for `MemTracker::tracking_level()` and `DumpSharedSpaces` into a single test and do more work only when the uncommon path is taken. This would require some refactoring of the MemTracker/MallocTracker code. I'd rather do that in a separate RFE.
> 
> In fact, `MemTracker::_tracking_level` is tested twice in the current implementation. We can change it to do a single test in the most common case (NMT_summary) if we really want to cut down the number of tests. But honestly I don't think this makes any difference.
> 

Before going down that road, I would really like to see some measurements, whether this really matters. malloc is not blindingly fast. The malloc code in glibc does test a lot of conditions too. If you need fast allocation (or well packed, for that matter), you need another allocator. Thats why we have Arenas.

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PR: https://git.openjdk.java.net/jdk/pull/7748