btrace

A safe, dynamic tracing tool for the Java platform

Quick Summary

BTrace is a safe, dynamic tracing tool for the Java platform.

BTrace can be used to dynamically trace a running Java program (similar to DTrace for OpenSolaris applications and OS). BTrace dynamically instruments the classes of the target application to inject tracing code ("bytecode tracing").

Credits

• Based on ASM
• Powered by JCTools
• Powered by hppcrt
• Optimized with JProfiler Java Profiler
• Build env helper using SDKMAN!

Building BTrace

Setup

You will need the following applications installed

• Git
• (optionally, the default launcher is the bundled gradlew wrapper) Gradle

Build

Gradle

cd <btrace>
./gradlew :btrace-dist:build

The binary dist packages can be found in <btrace>/btrace-dist/build/distributions as the *.tar.gz, *.zip, *.rpm and *.deb files. The exploded binary folder which can be used right away is located at <btrace>/btrace-dist/build/resources/main which serves as the BTRACE_HOME location.

Golden Files

Some of the instrumentor related tests are using golden files. Therefore, it is necessary to update those files when the injected code is changed. This can be done with the help of passing in updateTestData Gradle property. Eg. running the tests like ./gradlew test -PupdateTestData will regenerate all golden files which then must be checked in to the Git repository.

Using BTrace

Installation

Download a distribution file from the release page. Explode the binary distribution file (either *.tar.gz or *.zip) to a directory of your choice.

You may set the system environment variable BTRACE_HOME to point to the directory containing the exploded distribution.

You may enhance the system environment variable PATH with $BTRACE_HOME/bin for your convenience.

Or, alternatively, you may install one of the *.rpm or *.deb packages

Running

• <btrace>/bin/btrace <PID> <trace_script> will attach to the java application with the given PID and compile and submit the trace script
• <btrace>/bin/btracec <trace_script> will compile the provided trace script
• <btrace>/bin/btracer <compiled_script> <args to launch a java app> will start the specified java application with the btrace agent running and the script previously compiled by btracec loaded

For the detailed user guide, please, check the Wiki.

Maven Integration

The maven plugin is providing easy compilation of BTrace scripts as a part of the build process. As a bonus you can utilize the BTrace Project Archetype to bootstrap developing BTrace scripts.

Contributing - !!! Important !!!

Pull requests can be accepted only from the signers of Oracle Contributor Agreement