[Swift-devel] stracing jobs

[Mihael Hategan]

I added and option in the faster branch to strace wrapper invocations.

It's enabled with -Djob.perf.trace.interval=n and setting worker logging
level to WARN.

If set, every nth job submitted by the coaster service to a worker will
drop the logging level of that worker to DEBUG for the duration of the
job and invoke the wrapper with strace sticking the output in the same
dir as the worker logs.

This is because doing it for every job would be an unacceptable (and not
very useful) overhead, so this allows doing it sporadically so that the
numbers are more meaningful.

Mihael