 |
|
metracer is a tool to trace invocation of an arbitrary methods in Java programs. In some sense it's an analog of strace program. metracer is useful for:
- you want to quickly get acquainted with how a particular part of a Java program works - metracer will provide you with a call tree of a methods;
- you want to troubleshoot errors in Java program but debugger is not available - metracer will supply you with return values or exceptions thrown in a program;
- you want to spy for SQL statements issued by Hibernate in your JavaEE application - metracer will supply you with arguments of called methods.
- Download metracer JAR file from the latest release: https://github.com/kocherovms/metracer/releases/latest
- List Java programs available for tracing:
$ java -jar metracer.jar -l
PID NAME
6688 com.develorium.metracertest.Main
3726 org.pwsafe.passwordsafeswt.PasswordSafeJFace- Start tracing methods in a desired Java program using PID from the listing table, e.g.:
- to trace all methods from class
com.develorium.metracertest.Mainin Java program with PID 6688:
$ java -jar metracer.jar 6688 com.develorium.metracertest.Main
2016.06.18 11:31:33.749 [metracer.00000009] +++ [0] com.develorium.metracertest.Main.testBundle()
2016.06.18 11:31:33.749 [metracer.00000009] +++ [1] com.develorium.metracertest.Main.testA()
2016.06.18 11:31:33.749 [metracer.00000009] --- [1] com.develorium.metracertest.Main.testA => void
...- to trace only method
doSomethingfrom classcom.develorium.metracertest.Mainin Java program with PID 6688:
$ java -jar metracer.jar 6688 com.develorium.metracertest.Main doSomething
2016.06.18 11:31:14.721 [metracer.00000009] +++ [0] com.develorium.metracertest.Main.doSomething()
2016.06.18 11:31:14.726 [metracer.00000009] --- [0] com.develorium.metracertest.Main.doSomething => void
...- to trace all methods from classes
com.develorium.metracertest.Fooandcom.develorium.metracertest.Barin Java program with PID 6688:
$ java -jar metracer.jar 6688 'com.develorium.metracertest.Foo|Bar'
2016.06.19 12:00:17.312 [metracer.00000009] +++ [0] com.develorium.metracertest.Foo.perform()
2016.06.19 12:00:17.314 [metracer.00000009] --- [0] com.develorium.metracertest.Foo.perform => void
2016.06.19 12:00:17.315 [metracer.00000009] +++ [0] com.develorium.metracertest.Bar.perform()
2016.06.19 12:00:17.315 [metracer.00000009] --- [0] com.develorium.metracertest.Bar.perform => void
...- When you are done with tracing press q - this will stop methods tracing in a Java program and quit
There are other functions available in metracer (e.g. vertical instrumentation). Brief description of metracer functionality is available in a builtin help:
$ java -jar metracer.jar -hFor more detailed information on how to use metracer please visit http://develorium.com/metracer.
- ASM is used to instrument programs' code on the fly without a need to recompile anything;
- Java Attach API is used to inject tracing into target Java process (agent uploading);
- JMX is used to communicate and configure uploaded agent.
- Java 1.6 or higher;
- JDK is installed (tools.jar is needed).
Apace License, Version 2.0.