FlameViewer

Install Plugin

• Standalone command-line tool FlameViewer-1.0.jar

  java -jar FlameViewer-1.0.jar path/to/my_app.jfr
  

• Plugin for JetBrains IDEs: https://plugins.jetbrains.com/plugin/10305-flameviewer

Table of contents

• Uploading file to FlameViewer
• Java performance recording. Quick start
• FlameViewer Features
  • Call Traces
  • Back Traces
  • Zoom
  • Filtering
  • Search
  • Hot Spots
  • Call Tree
  • Detailed View of Thread
• Building from sources

Uploading file to FlameViewer

1. Click Tools | Open FlameViewer...
2. Upload a file of a supported profiler:
   1. jfr files generated by Flight Recorder
   2. Yourkit csv files. To generate csv file from a snapshot run following script: java -jar -Dexport.call.tree.cpu -Dexport.csv /lib/yjp.jar -export ~/Snapshots/.snapshot
   3. Files in flamegraph format
   4. fierix files generated by Fierix profiler

Java performance recording. Quick start

Use Flight Recorder to profile your program and then open FlameViewer:

1. Make sure you are using Oracle JDK (not OpenJDK) because Java Mission Control comes only with Oracle JDK. To do it open File | Project Structure... | Project then click Edit beside Project SDK, look at JDK home path it should be something like this: .../jdk1.8.0_162 not like this: .../java-8-openjdk-amd64. You can download needed version from Oracle website: JDK 8, JDK 9
2. Run JVM with following VM options: -XX:+UnlockCommercialFeatures -XX:+FlightRecorder -XX:StartFlightRecording=duration=30s,filename=my_recording.jfr -XX:FlightRecorderOptions=stackdepth=256
3. Open FlameViewer Tools | Open FlameViewer...
4. Upload my_recording.jfr

FlameViewer Features

Flamegraph Visualizer helps you to analyze performance of Java program. It draws a flamegraph where x-axis represents time and y-axis shows stack depth.

Each rectangle represents a method. If a rectangle is wide it means that your program spent a lot of time executing this method and methods that were called within it.

Basically you are looking for rectangles that have a wide "roof" that does not have any other method calls. It means that your program spent a lot of time executing this method.

Call Traces

This flamegraph accumulates all stacktraces of profiled program. One rectangle represents one or multiple calls of method.

If you place the cursor on the method's rectangle you will see popup with detailed information about method.

If you click on call-traces/back-traces icon on a popup (blue icons at the top of popup) you will see call-traces/back-traces tree for the method (this tree accumulates information from all calls of the method).

Back Traces

Back Traces is the bottom-up tree. It shows methods that called the method on the top of flamegraph. This flamegraph may be helpful if you know that some method was called a lot of times and you want to know what is the reason for it.

Zoom

Click on a rectangle to zoom in on it.

Filtering

Regexp for filtering method calls e.g. my\.package.*|another\.package.*.

Search

You can find any method, class or package using search.

Tips:

• Character '*' matches any sequence of characters.
• If profiler saved values of parameters, you may include them in search string. For example: resolve(*, *IdeaPlugin.xml

Hot Spots

On Hot Spots page you can see where your program spent the most time.

Call Tree

This page is only for .ser files
On Call Tree page you can see activity of all threads. To see what was happening inside particular thread you should click on it's name.

Detailed View of Thread

This page is only for .ser files
On this page you can see what was happening inside some thread. All method calls have original order. Each rectangle represents only one method call.
You can see popup with detailed information about method if you place the cursor on the method (also there are parameters and return value if they were saved).

Building from sources

If only want to use plugin then you should simply install ready-to-use jar.

./gradlew :visualization:copyStatic
./gradlew :intellij-plugin:runIdea

Regenerate flatbuffers

cflamegraph_schema.fbs has to be regenerated after flatbuffers compiler and flatbuffers runtime library are updated.

chmod +x ./scripts/install-flatbuffers.sh
./scripts/install-flatbuffers.sh
./gradlew :core:compileFlatBuffers