RFR: 8335358: [premain] Explore alternative ways to trigger the end of training run [v15]

[Ioi Lam]

On Wed, 20 Nov 2024 19:10:56 GMT, Vladimir Ivanov <vlivanov at openjdk.org> wrote:

> Nice work, Mat! 
> 
> 
> 
> Speaking of proposed API, there's a lot of complexity around `-XX:AOTEndTrainingOnMethodEntry=`. What's the primary use case for it? Does it add much for uncooperative case (no application changes) compared to `jcmd`?
> 
> 
> 
> For cooperative case, a dedicated method in JDK an application can call seems more appropriate.

I think this PR has its benefits:

- JCMD triggers are imprecise. If you using jcmd to trigger the end of training based on time, or based on parsing the app's log, it may capture too much or too little profile.

- An API would require modifying the app.

So this PR allows precise timing  (for apps that have a well-known Java method that's called during important state transition) without modifying the app itself.

-------------

PR Comment: https://git.openjdk.org/leyden/pull/21#issuecomment-2491867215