Add on demand profiling / heapdump

[megastef]

It would be nice to trigger CPU profiler and heapdump via SIGHUB, file or socket.

https://www.npmjs.com/package/v8-profiler
https://www.npmjs.com/package/heapdump

[otisg]

Mmmm, yum. Would be even nicer to be able to get it into SPM, like the JVM profiler data - https://sematext.com/blog/2016/03/17/on-demand-java-profiling/