A tiny CPU profiler for Java written completely in Java 11.
This is an educational sampling profiler from Johannes Bechberger that helps demystify profilers, but is not limited to it.
The changes I have made here are exclusively to the operability of the profiler with Java 11.
This profiler is a sampling profiler with can output method tables and
flame graphs (via d3-flame-graph).
The sampling is based on the Thread.getAllStackTraces() method, making it simple but also safepoint-biased.
The profiler should work on any platform with a JDK 11 or newer. The usage is fairly simple:
# build it
mvn package
# run your program and print the table of methods sorted by their sample count
# and the flame graph, taking a sample every 10ms
java -javaagent:target/tiny-profiler.jar=flamegraph=flame.html ...Example:
Profiling the included fibonacci benchmark:
> java -javaagent:target/tiny-profiler.jar=flamegraph=flames.html Fib.java 40
===== method table ======
Total samples: 54
Method Samples Percentage On top Percentage
com.sun.tools.javac.launcher.Main.run 53 98,15 0 0,00
com.sun.tools.javac.launcher.Main.main 53 98,15 0 0,00
com.sun.tools.javac.launcher.Main.compile 28 51,85 0 0,00
java.lang.reflect.Method.invoke 25 46,30 0 0,00Profiling the Renaissance benchmark suite:
# download a benchmark
> test -e renaissance.jar || wget https://github.com/renaissance-benchmarks/renaissance/releases/download/v0.14.2/renaissance-gpl-0.14.2.jar -O renaissance.jar
> java -javaagent:./target/tiny-profiler.jar=flamegraph=flames.html -jar renaissance.jar dotty
...
===== method table ======
Total samples: 11217
Method Samples Percentage On top Percentage
dotty.tools.dotc.typer.Typer.typed 59499 530.44 2 0.02
dotty.tools.dotc.typer.Typer.typedUnadapted 31050 276.81 7 0.06
scala.runtime.function.JProcedure1.apply 24283 216.48 13 0.12
dotty.tools.dotc.Driver.process 19012 169.49 0 0.00
dotty.tools.dotc.typer.Typer.typedUnnamed$1 18774 167.37 7 0.06
dotty.tools.dotc.typer.Typer.typedExpr 18072 161.11 0 0.00
scala.collection.immutable.List.foreach 16271 145.06 3 0.03
...This results in the following flamegraph:
The overhead for this example is around 2% on my MacBook Pro 13" for a 10ms interval, which makes the profiler usable when you ignore the safepoint-bias.
- Main class: Entry point of the Java agent
- Options: Parses and stores the agent options
- Profiler: Contains the profiling loop
- Store: Stores and outputs the collected results
- MethodTableEntry: Replacement of record for Java 11
MIT, Copyright 2023 SAP SE or an SAP affiliate company, Johannes Bechberger and tiny profiler contributors
This project is a prototype of the SapMachine team at SAP SE