Issue2278

Jython logs to stderr, up to a verbosity level of -vvv, a variety of runtime events, most notably in import resolution. The logging code is simple: https://github.com/jythontools/jython/blob/master/src/org/python/core/Py.java#L1992

It would be helpful to get more detailed runtime output by expanding what is logged; choice of output log; and especially with timestamps. Such instrumentation could help diagnose problems in say excessively long import times.

We should look at integrating with some widely used instrumentation package in doing so.

I noticed I'd somewhat duplicated this in #2778. I didn't spot it as a duplicate because of the title majoring on "runtime instrumentation", whereas richer logging is what's really on my mind in #2778.

I'm not sure what "runtime instrumentation" means, but I'm working on the assumption that if we get the logging in place (with timestamps, the instrumentation needed is a thing that consumes it.

Logging is not the right mechanism if investigation needs micro-benchmarks, but it is good for finding what phases of start-up, or an application, are costly.