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Profiling with Traceview and dmtracedump

Željko Plesac

Android talks #9

Scope

• Traceview

• dmtracedump

• StrictMode

• Real world example

Profiling (1)

• form of dynamic program analysis that measures, for example, the space (memory) or time complexity of a program, the usage of particular instructions, or the frequency and duration of function calls.

• Most commonly, profiling information serves to aid program optimisation.

Profiling(2)

• It is very important for Android applications to perform all operations as fast as possible.

• if your application is has long execution time and everything else fails, you’ll need to use profiling to debug those nasty errors and bugs

Profiling(3)

• 2 programs which come bundled in Android SDK:

1. Traceview

2. dmtracedump

Trace files(1)• to use profiling, we first need to generate log files

containing the trace information you want to analyse.

• two ways:

1. Use Debug class

2. Use the method profiling feature of DDMS to generate trace logs (less precise)

Trace files(2)

• Include the Debug class in your code and call its methods such as startMethodTracing() and stopMethodTracing(), to start and stop logging of trace information to disk.

• your application must have permission to write to external storage

Traceview(1)• graphical viewer for execution logs that you create by using

the Debug class to log tracing information in your code

• can help you debug your application and profile its performance

• two layouts

1. Timeline panel - describes when each thread and method started and stopped

2. Profile panel - provides a summary of what happened inside a method

Traceview(2) - Timeline panel

Each thread’s execution is shown in its own row, with time increasing to the right. The thin lines underneath the first row show the extent (entry to exit) of all the calls to the selected

method.

Traceview(3) - profile panel

Traceview(4)• table shows both the inclusive and exclusive times

(as well as the percentage of the total time):

1. exclusive time - time spent in the method

2. inclusive time - time spent in the method plus the time spent in any called functions

• The last column in the table shows the number of calls to this method plus the number of recursive calls

dmtracedump

• generates the call stack data as a tree diagram, with each call represented as a node.

• it shows call flow (from parent node to child nodes) using arrows

• Graphviz Dot utility is needed to create graphical output

dmtracedump(2)

each node, dmtracedump shows <ref> callname (<inc-ms>, <exc-ms>,<numcalls>)

Strict mode(1)

• You should avoid performing long running operations on the UI thread. This includes file and network access.

• StrictMode you can instruct the Android system to crash your application if it performs long running operations, e.g. I/O in the user interface thread.

Strict mode(2)

Real world example

Real world example

• client reported that application has long startup time on Samsung devices

• tested on Samsung Galaxy Tab 2.0. - startup time is longer than 25 seconds

• firstly we scanned the app with StrictMode - no long running operations were found on the UI thread

• secondly, we optimised ActiveAndroid ORM library by manually specifying database models in Android manifest

• with this step we optimised app startup by 4 seconds

• after that debugging didn’t help, so we needed to use profiling

Traceview

dmtracedump

• after examining the tracefile, we noticed strange behaviour with MagicViews external library

• turns out that this library scans all asset folders (either our application or external dependencies assets) looking for custom fonts

• after replacing MagicViews with custom implementation of UI elements, we downgraded the app startup time to less than 2 seconds

Conclusion

• Profiling is something we usually use as a last resort

• it will not automatically fix all of your problems, but it’ll just give you a brief insight to your application behaviour

• TraceView is deprecated - use Android Device Monitor (tools/monitor) instead