RFR: JDK-8318636: Add jcmd to print annotated process memory map

[Thomas Stuefe]

On Mon, 23 Oct 2023 01:39:16 GMT, Chris Plummer <cjplummer at openjdk.org> wrote:

> The hs_err file includes a dump of the maps file. It seems these annotations would be useful there also.

I thought about this too. The problem is the printing may take long since it is O^2 (iterate through VMAs, for each one iterate NMT regions). We had cases where the process ran with >20 mio VMAs (ZGC with a 5TB heap).

But thinking further, this is a problem anyway, since the hs-err file was >2GB. And we do have per-step timeouts in the hs-err writer. So, stopping after a set number of VMAs (lets say 100k, that covers 99% of all processes) and otherwise relying on the hs-err timeout code may be ok.

I'll give it a shot.

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PR Comment: https://git.openjdk.org/jdk/pull/16301#issuecomment-1774459066