RFR: JDK-8324287: Record total and free swap space in JFR [v2]

[Johannes Bechberger]

On Fri, 26 Jan 2024 14:43:50 GMT, Matthias Baesken <mbaesken at openjdk.org> wrote:

>> Total and free swap space should be recorded in JFR, because it is important to know e.g. in case of memory shortages.
>> 
>> Currently we only have a container related event (ContainerMemoryUsage) that provides some info but no general event.
>> PhysicalMemory could be enhanced or a new event added.
>> 
>> There is already some coding (see Java_com_sun_management_internal_OperatingSystemImpl_getTotalSwapSpaceSize0 and
>> Java_com_sun_management_internal_OperatingSystemImpl_getFreeSwapSpaceSize0) for the swap space info retrieval.
>
> Matthias Baesken has updated the pull request incrementally with one additional commit since the last revision:
> 
>   remove comment

Marked as reviewed by jbechberger (Committer).

src/hotspot/share/jfr/metadata/metadata.xml line 931:

> 929: 
> 930:   <Event name="SwapSpace" category="Operating System, Memory" label="Swap Space" description="OS Swap Space" period="everyChunk">
> 931:     <Field type="long" contentType="bytes" name="totalSize" label="Total Size" description="Total swap space available to OS" />

"to the OS", sorry for the nitpicking. The PR looks good otherwise.

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PR Review: https://git.openjdk.org/jdk/pull/17581#pullrequestreview-1848086354
PR Review Comment: https://git.openjdk.org/jdk/pull/17581#discussion_r1469234741