Optimize coverage analysis

[andre15silva]

Hot spots of the test-runner process started by flacoco on math_70:

Self times

Expanded self times for the top result. This highlights that the most time consuming operation is analyzing the instrumented classes after execution.

Total times

Where to optimize?

1. Coverage analysis for sure. This is the most time consuming operation with ~77% of cpu time being used there. (169s/218s)

(This is copied from ASSERT-KTH/flacoco#74)

[andre15silva]

A possible path to optimize is to use online instrumentation (See https://www.eclemma.org/jacoco/trunk/doc/agent.html)

[andre15silva]

FYI, I'm experimenting with online instrumentation with JMX.

See https://github.com/andre15silva/test-runner/tree/online-prototype, working prototype but it is slower from my tests.

[andre15silva]

Btw @danglotb, I got online instrumentation working but it was even slower, so I gave up on that.

You might want to read the last two comments of ASSERT-KTH/flacoco#74, if you want to keep up to date with the optimization effort.