28-May-2018 Bill Torcaso bill@billtorcaso.org

This Java code contains a thread-safe Stopwatch object that is useful for performance testing.

The idea is that the Stopwatch captures named moments for later review.
Multiple threads can record moments on the same Stopwatch. The Stopwatch never does I/O, so it has minimal impact on run-time.

You can nest beginning and ending "tasks", like this:

000000168000 TaskBegin:Genus 000000171000 | Pan (all chimpanzees) 000000176000 | TaskBegin:Species 000000183000 | | Troglodytes 000000187000 | | TaskBegin:Movie Stars 000000189000 | | | Cheetah - Tarzan's companion 000000195000 | | TaskEnd:Movie Stars 000000201000 | | TaskBegin:Subspecies 000000208000 | | | schweinfurthi 000000212000 | | | TaskBegin:Alpha Male 000000215000 | | | | Frodo - Jane Goodall's companion 000000220000 | | | TaskEnd:Alpha Male 000000223000 | | TaskEnd:Subspecies 000000227000 | TaskEnd:Species 000000230000 TaskEnd:Genus

The Stopwatch will give you a sequential List anytime you ask for it.

I typically let a program run to completion and then use one of these methods to eyeball the hot spots:

prettyPrint(taskRelative)

prettyPrint(previousMomentRelative)

You can create many independent Stopwatch objects. For profiling legacy code, there is singleton Stopwatch available through the factory. This means that you can have a legacy library generate some timings, and easily print them from main().

There are other display services:

creationMomentRelative
nanoTimeValues
toStringAsIntervals
toString

The Stopwatch records in nanosecond units. The precision depends on the underlying host and its clock.

StopwatchFactory.java has a main() to run tests. See Test-output.txt. Start it this way:

java -cp . org.billtorcaso.kutils.StopwatchFactory

There is full javadoc in the apidocs/ directory.

Feedback welcome.