README.md

Description

Health report is Java agent that illustrates how the JFR Event Streaming API can be used.

The agent runs alongside with an ordinary Java application and prints data produced by JFR to standard out.

Health report requires JDK 14, or later, and only works on OpenJDK/Oracle JDK.

Build instructions

cd src
javac Main.java
jar cmf META-INF/MANIFEST.MF health-report.jar .

Usage

To run Health report as a Java agent:

$ java -javaagent:health-report.jar MyApp

To run Health report against itself:

$ java Main.java

For a demonstration see:

https://youtu.be/E9K5m1HXMSc?t=367

Example output:

=================== HEALTH REPORT === 2019-05-16 23:57:50 ====================
| GC: G1Old/G1New         Phys. memory: 28669 MB    Alloc Rate: 8 MB/s       |
| OC Count    : 28        Initial Heap: 448 MB      Total Alloc: 190 MB      |
| OC Pause Avg: 40.1 ms   Used Heap   : 19 MB       Thread Count: 20.0       |
| OC Pause Max: 48.8 ms   Commit. Heap: 47 MB       Class Count : 3894.0     |
| YC Count    : 8         CPU Machine   :  20.12 %  Safepoints: 335          |
| YC Pause Avg: 5.7 ms    CPU JVM User  :  10.28 %  Max Safepoint: 46.4 ms   |
| YC Pause Max: 22.4 ms   CPU JVM System:   1.07 %  Max Comp. Time: 728.3 ms |
|--- Top Allocation Methods ------------------------------- -----------------|
| DataBufferInt.(int)                                                11.27 % |
| Component.size()                                                    9.01 % |
| BufferedContext.validate(...)                                       6.21 % |
| Path2D$Double.(...)                                                 5.87 % |
| SunGraphics2D.clone()                                               5.85 % |
|--- Hot Methods ------------------------------------------------------------|
| DRenderer._endRendering(int, int)                                  51.11 % |
| DRenderer.copyAARow(...)                                            6.67 % |
| Arrays.fill(...)                                                    4.44 % |
| StringConcatFactory.doStringConcat(...)                             2.22 % |
| MarlinTileGenerator.getAlphaNoRLE(...)                              2.22 % |
==============================================================================