Write the log in XML format suitable for VisualVM 'UI Actions'

[JaroslavTulach]

Pull Request Description

Start project-manager with following options to provide first 20s of the startup sequence:

$ project-manager --profiling-events-log-path=start.log --profiling-path=start.npss --profiling-time=20

once the start.log and start.npss files are generated (next to each other), open them in GraalVM's VisualVM:

$ graalvm/bin/jvisualvm --openfile start.npss

analyze.

Checklist

Please include the following checklist in your PR:

• The documentation has been updated if necessary.
• All code conforms to the
  Scala,
  Java,
  style guides.
• All code has been tested:
  • Manually tested

[JaroslavTulach]

VisualVM shows timeline with "stackdepth" and also "UI Actions". Hovering over boxes in "UI Actions" shows the messages describing what happens in the engine. One can then select an interval and get profiling information for that interval:

This picture shows that 2.7s is spend in compiler.

[JaroslavTulach]

@4e6, is it OK to just switch the format to XML? Or do we rely on the original format somewhere?

[4e6]

I think the CSV output can be used by IDE profiling. Maybe we should ask @kazcw or @MichaelMauderer

[JaroslavTulach]

@kazcw, @MichaelMauderer can you take a look? I am not aware of any (finished) attempt to merge the IDE and engine logging together, but I may not have the overall picture. CCing @xvcgreg...

[hubertp]

Can we have these steps documented, please?

[JaroslavTulach]

Can we have these steps documented, please?

Here is the documentation for your consideration, @hubertp.

[hubertp]

Documentation looks good, thanks!