Quick Start:
- Download BTrace from here
- Extract the release to a directory e.g.
~/btrace - Write a BTrace program. There are many samples present in the
samplesdirectory. Here is one of mine: the program below prints a message whenever the target program calls theArrayList.add()method.
import com.sun.btrace.annotations.*;
import static com.sun.btrace.BTraceUtils.*;
import java.util.*;
@BTrace
public class ArrayListTrace {
// @OnMethod annotation tells where to probe.
// In this example, we are interested in entry
// into the ArrayList.add() method.
@OnMethod(
clazz="java.util.ArrayList",
method="add";
)
// print out what was added
public static void alert(@Self ArrayList self, Object o) {
print("ADDED ");
println(o);
}
}
javac -cp "~/btrace/build/*" ArrayListTrace.java
~/btrace/bin/btrace -cp ".:~/btrace/build/*" <PID> ArrayListTrace.classUseful BTrace Programs:
Here are a few useful BTrace programs I have used in the past:
- OnThrow: Prints out the stack trace of an exception whenever a Throwable is created. This way you can capture all exceptions, even those that have been swallowed.
- LogTracer: Prints out log messages.
- AllMethods: Prints out the name of every method entered.
