RFR: 8342444: Shenandoah: Uncommit regions from a separate, STS aware thread [v7]

[William Kemper]

On Mon, 25 Nov 2024 17:28:19 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> Hmm, the numbers are preceded by `Concurrent uncommit`, with that context it's not much of a stretch to think these numbers represent the change in _committed_ memory. The original log message (in which heap usage may increase during uncommit) was _not_ helpful. A message with the same format in which heap usage also appears to _not change at all_ during an uncommit is also perplexing. Are we trying too hard to preserve the original, not useful message? Maybe we just want a new message that plainly says: 
>> 
>> 
>> Concurrently uncommitted XXXXM in z.zzzms
>> 
>> or
>> 
>> Concurrent uncommit: time z.zzzms, committed before XXXXM, committed after YYYYM, capacity ZZZZM
>
> Yes, I don't want to emit something that looks like a heap usage GC log line, if it is not. Unfortunately, `X->Y (Z) T.TTTTms` is a common format for X and Y as heap use. I agree posting X == Y would be only marginally better. So, maybe this goes as middle ground:
> 
> 
> Concurrent uncommit XXXXM (YYYYM) z.zzzms
> 
> 
> ...where XXXX is the amount uncommitted, YYYY is the final heap capacity?

Okay, this looks good.

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PR Review Comment: https://git.openjdk.org/jdk/pull/22019#discussion_r1857092060