Add support for Context ID functionality

[dpsoft]

async-profiler/async-profiler#576

[parttimenerd]

I thought about creating an ap-loader version that packages the related async-profiler version, any thoughts?

[dpsoft]

I think is a good idea!

[dpsoft]

@parttimenerd I'm just starting to throw some lines on an idea of how to interact with the contextId and it would be very helpful to be able to play with a version of AP-Loader with those changes.

[parttimenerd]

I want to hear the opinion of @krzysztofslusarski first

[krzysztofslusarski]

My PR for context ID is just a first step to contextual profiling. What it does is basically a possibility to mark each dumped stack trace with context ID.

Now, context is something more than an ID. In the future that functionality could be expanded into passing some properties/map into JFR, so everything is in one file (either in AP or JDK JFR). For now (as a user of context ID async profiler) you need to be able to connect context ID with context by yourself.

For example, here is a way to connect spring with contextual profiling: https://krzysztofslusarski.github.io/2022/12/12/async-manual.html#context-id-spring - connection between request to spring and context ID is completely missing. The context id is lowerHexToUnsignedLong(traceContext.traceId()). It would be easy to log that value in file to have a connection between JFR and request if needed.

Without maintaining context elsewhere you can:

• try to figure out how long context was alive (max(time) from stactraces - min(time) from stactraces)
• filter JFR (and multiple JFRs) by context ID
• put in as a level on a flame graph (or any other visualization)
  For now, my viewer is probably the only tool that support such features.

I strongly believe that context profiling is the future of that job, so any work towards promoting it is more than welcome.

[parttimenerd]

As a first step, I could package your PR into an experimental ap-loader artifact.

[krzysztofslusarski]

Sure, but please merge master with it.

[parttimenerd]

@krzysztofslusarski I cannot rebase in your repo, so the question is how/where to maintain your PR

[krzysztofslusarski]

Sure. I just pushed merged master into my branch.

[parttimenerd]

The experimental ap-loader artifacts are currently not at the top of my list of tasks, so it might take a few weeks till I come around.

I propose we build different (experimental) versions of async-profiler and package as ap-loader artifacts. We could ship the context-id patch in ap-loader-cid-{all,macos,...} artifacts. This is not too hard to add to my publishing python script. So if anyone wants to try to implement it... I'm happy for any PRs (and glad to help).