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Tracing Dalvik VM (Java) applications on Android

Android's Java virtual machine, Dalvik, runs as a system service (started at bootup by init) and Java applications are run by forks of the initial resident process. Thus, injecting apitrace's tracing library is different from other operating systems.

The following discussion assumes that tracing library is copied to '/data':

adb push /path/to/apitrace/build/wrappers/egltrace.so /data

Tracing on Android 4.0 and newer

Starting from Android 4.0 (Ice Cream Sandwich) release, Dalvik supports running designated processes with wrappers, in which case a new Java VM is started with 'system()' library call for that process.

Obtain the process name of the application to be traced (the one reported in ps output, such as com.android.settings), and set two system properties:

PROCNAME=com.android.settings
adb root
adb shell setprop wrap.$PROCNAME LD_PRELOAD=/data/egltrace.so
adb shell setprop debug.apitrace.procname $PROCNAME

(the former is read by Dalvik and specifies wrapping prefix, the latter is read by apitrace itself and used in case apitrace is preloaded into Java VM globally to specify which process should be traced). Elevating priviliges via adb root is required to set the first property.

Make sure the process is not loaded before starting to trace it, for example use -S flag to am start:

adb shell am start -S $PROCNAME

Use adb logcat \*:S apitrace to examine apitrace debug output. Trace files are saved into '/data/data/$PROCNAME' directory by default:

adb pull /data/data/$PROCNAME/$PROCNAME.trace
adb shell rm /data/data/$PROCNAME/$PROCNAME.trace

Tracing on Android pre-4.0

LD_PRELOAD is supported since Android 2.3 "Gingerbread" and newer, but injecting tracing library globally is no longer supported, as the debug.apitrace.procname system propery is no longer honored.

Consider checking out an older commit if you need to trace on Android pre-4.0.