RFR: 8365306: Provide OS Process Size and Libc statistic metrics to JFR

[Thomas Stuefe]

On Tue, 19 Aug 2025 06:43:01 GMT, Erik Gahlin <egahlin at openjdk.org> wrote:

> What is the problem with adding RSS metrics to the existing ResidentSetSize event?

You mean adding the vsize, swap etc fields to ResidentSetSize?

I thought about that, but then it would be weirdly misnamed. RSS has a very specific meaning. So we would have ResidentSetSize.vsize, ResidentSetSize.swap, ResidentSetSize.rss (?) 

I also thought about splitting them up and add one event per value, following the "ResidentSetSize" pattern. So, one event for  "VirtualSize", one for "Swap" etc. Apart from not liking the fine granularity, having these fields grouped in one event has multiple advantages. Mainly, I can build myself graphs in JMC for all these fields in one graph and correlate all the values. It is also cheaper to obtain (just one parsing operation for /proc/meminfo, for instance).

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PR Comment: https://git.openjdk.org/jdk/pull/26756#issuecomment-3199479458