Best method to measure execution time in Android?

Question

What is best method to measure execution time of Android code snippet?

I have a section of code before and after which I want to place timestamps to find out it's execution time (e.g. one in onCreate() and another in onDestroy() method of activity).

I have tried Time.toMillies(false), but it only returns seconds to me (with constant 000 at the end). I also tried two java functions: System.currentTimeMillis() and System.nanoTime(). First one returns milliseconds of epoch time, second doesn't.

What would be the best way to measure execution time and get good precision?

Answer 1

What about TimingLogger?

From TimingLogger documentation:

TimingLogger timings = new TimingLogger(YOUR_TAG, "methodA"); // ... do some work A ...  timings.addSplit("work A"); // ... do some work B ...  timings.addSplit("work B"); // ... do some work C ...  timings.addSplit("work C"); timings.dumpToLog(); 

and the dump will look like:

     D/TAG     (3459): methodA: begin      D/TAG     (3459): methodA:      9 ms, work A      D/TAG     (3459): methodA:      1 ms, work B      D/TAG     (3459): methodA:      6 ms, work C      D/TAG     (3459): methodA: end, 16 ms 

Do not forget to enable your tag by running: adb shell setprop log.tag.YOUR_TAG VERBOSE

Answer 2

What would be the best way to measure execution time

System.nanoTime() is probably a good choice. Jake Wharton is using that with Hugo, for example.

and get good precision

This is not strictly possible, as anything can happen on the device while your method is executing. Those external factors will affect your time measurements, by stealing away CPU time, tying up I/O channels, etc. You need to average your tests across several runs to try to average out those external factors, and accuracy/precision will suffer as a result.

And, as Marcin Orlowski notes, to actually figure out why you are consuming certain amounts of time, use Traceview.