Titrace

Titrace is a bytecode instruction tracing tool that uses JVMTI and works on both ART and the RI.

Usage

Build

make libtitrace # or 'make libtitraced' with debugging checks enabled

The libraries will be built for 32-bit, 64-bit, host and target. Below examples assume you want to use the 64-bit version.

Command Line

ART

art -Xplugin:$ANDROID_HOST_OUT/lib64/libopenjdkjvmti.so -agentpath:$ANDROID_HOST_OUT/lib64/libtitrace.so -cp tmp/java/helloworld.dex -Xint helloworld

• -Xplugin and -agentpath need to be used, otherwise libtitrace agent will fail during init.
• If using libartd.so, make sure to use the debug version of jvmti.

Reference Implementation

java -agentpath:$ANDROID_HOST_OUT/lib64/libtitrace.so helloworld

Only needs -agentpath to be specified.

Android Applications

Replace com.littleinc.orm_benchmark with the name of your application below.

Enable permissions for attaching an agent

Normal applications require that debuggable=true to be set in their AndroidManifest.xml.

By using a eng or userdebug build of Android, we can override this requirement:

adb root adb shell setprop dalvik.vm.dex2oat-flags --debuggable

Then restart the runtime to pick it up.

adb shell stop && adb shell start

If this step is skipped, attaching the agent will not succeed.

Deploy agent to device

The agent must be located in an app-accessible directory.

adb push $ANDROID_PRODUCT_OUT/system/lib64/libtitrace.so /data/local/tmp

Upload to device first (it gets shell/root permissions).

adb shell run-as com.littleinc.orm_benchmark 'cp /data/local/tmp/libtitrace.so /data/data/com.littleinc.orm_benchmark/files/libtitrace.so'

Copy the agent into an app-accessible directory, and make the file owned by the app.

Attach agent to application

Option 1: Attach the agent before any app code runs.

adb shell am start --attach-agent /data/data/com.littleinc.orm_benchmark/files/libtitrace.so com.littleinc.orm_benchmark/.MainActivity

Note: To determine the arguments to am start, launch the application manually first and then look for this in logcat:

09-14 13:28:08.680 7584 8192 I ActivityManager: Start proc 17614:com.littleinc.orm_benchmark/u0a138 for activity com.littleinc.orm_benchmark/.MainActivity

Option 2: Attach the agent to an already-running app.

adb shell am attach-agent $(pid com.littleinc.orm_benchmark) /data/data/com.littleinc.orm_benchmark/files/libtitrace.so

Printing the Results

All statitics gathered during the trace are printed automatically when the program normally exists. In the case of Android applications, they are always killed, so we need to manually print the results.

kill -SIGQUIT $(pid com.littleinc.orm_benchmark)

Will initiate a dump of the agent (to logcat).