RFR: JDK-8329605: hs errfile generic events - introduce sections for Frequent/NotFrequent Events [v3]

[Lutz Schmidt]

On Tue, 9 Apr 2024 07:31:23 GMT, Matthias Baesken <mbaesken at openjdk.org> wrote:

>> Currently the 'generic' hs_errfile Events message log (filled  by Events::log) is rather flooded by messages for memory protection operations. Those seem to occur quite often and move out other less frequent events, because the number of entries in the log is limited.
>> It might be better to separate the frequent and less frequent events into 2 sections. The memory protection events would go into the frequent events section.
>> The mentioned memory protection operations related entries look like this :
>> Event: 0.178 Protecting memory [0x000000016ebf0000,0x000000016ebfc000] with protection modes 0
>
> Matthias Baesken has updated the pull request incrementally with one additional commit since the last revision:
> 
>   adjust typo

LGTM - given the scope of this PR.
In general, I don't like the event log to be split into multiple streams being printed separately. Yes, separate sections prevent displacement of events by other, too verbose, events. On the other hand, time coherence is lost or has to be manually re-established by the support engineer. Often enough, an issue can only be understood when seeing multiple/all events in timely order. 

Merging the event sections at print time by timestamp would be a helpful enhancement.

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Marked as reviewed by lucy (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/18626#pullrequestreview-1989536222