ASML_FlightRecorderMeetsJava.pdf
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Miroslav Wengner's presentation covers the integration of Java Flight Recorder (JFR) into modern Java, detailing its evolution from the acquisition by Oracle to its open-sourcing. JFR is a low-overhead event tracing framework built into the Java Virtual Machine, aiding in performance profiling and root-cause analysis for applications. The talk includes insights into JFR's functionalities, enhancements in recent releases, and practical examples of its application in monitoring and optimizing Java applications.
![References:
⢠Project Amber: https://openjdk.org/projects/amber/
⢠Project Loom: https://openjdk.org/projects/loom/
⢠JFR Project: https://github.com/openjdk/jmc
⢠OpenJDK: https://openjdk.org/
⢠JEP-349 JFR Event Steaming: https://openjdk.org/jeps/349
⢠foojay.io: https://foojay.io/today/author/miro-wengner/
⢠OpenValue Blog: https://openvalue.blog/
Book In Progress: Practical Design Patterns for Java Developers [PACKT]](https://image.slidesharecdn.com/asmlflightrecordermeetsjava-221028092411-de11203e/85/ASML_FlightRecorderMeetsJava-pdf-34-320.jpg)
ASML_FlightRecorderMeetsJava.pdf
- 2. Safe Harbour Statement All what you will hear can be di ff erent, this presentation is for motivational purposes âŚ
- 3. Miroslav Wengner ⢠Husband, Father, Software Engineer, Technology Enthusiast ⢠JCP: Executive Committee Board Member ⢠OpenJDK Committer , Java Mission Control Project, Open-Source ⢠Co-Author of Robo4J Project (Duke Award) ⢠Java Champion, JavaOne RockStar, Blogger ⢠Principal Engineer at OpenValue
- 4. ⢠Group Of Talented and Motivated Individuals ⢠Netherlands, Germany, Switzerland, Austria⌠⢠Fun, Development, Trainings, Migration and moreâŚ
- 5. Application Crash No Relevant Information Adding a Logging Performance Penalties Removing Logging
- 6. Agenda ⢠History in nutshell ⢠JMC and Flight Recorder in bullet points ⢠JFR under the hood ⢠JFR in Action and Examples ⢠Power of Data Visualisation ⢠What about JDK improvements and upcoming features? ⢠Q/A
- 7. History in nutshell ⢠1998 Appeal Virtual Machines (AVM) - JRockit JVM ⢠2002 AVM acquired by BEA ⢠2008 acquired by Oracle ⢠2012 JDK 7u4 update: Oracle integrated JFR into the HotSpot ⢠2017 JDK 9 : Public APIs for creating and consuming data ⢠2018 JDK 11: JMC/JFR announced to be fully Open-Sourced
- 8. JFR in bullets ⢠Part of Java Mission Control project ⢠Java Flight Recorder is an event based tracing framework ⢠Build directly into the Java Virtual Machine ⢠Provides access to all internal events ⢠Allows to create custom events ⢠Tries to achieve a goal 1% overhead
- 9. JFR meets Java Platform ⢠Compiled to byte-code ⢠Usage of JIT Compiler ⢠Byte code optimisation ⢠module, package: jdk.jfr
- 10. Profiling with JFR ⢠Observability allows to measure a system based on provided data metrics (local, on-prem or cloud) ⢠each application may have di ff erent telemetry, di ff erent assumptions ⢠hardware, container, end-points, librariesâŚ. ⢠Monitoring -> keeping yes on sampled data ⢠Pro fi ling -> recording and analysing ârealâ data https://www.hippopx.com/en/camera-security-monitoring-big-brother-control-surveillance-camera-video-surveillance-81117
- 11. Common Usage of JFR ⢠Micros-Services, Distributes and Stand-Alone applications ⢠helps in root-cause analysis ⢠application understanding, bottlenecks ⢠solution correctes ⢠testing ⢠monitoring Letâs split More Pods thereâŚ
- 12. Java Mission Control Project Current release 8.3 Release Milestone Date ========== =========== ========== 8.2.0 GA 2022-01-19 8.2.1 GA 2022-06-16 8.3 EA 2022-10-11 8.1 : New Allocation Events for JDK 16, ⢠JMC Agent, JMC Agent Plugin ⢠Performance Improvements : Perser, Rules 8.2: Minor release ⢠JFR: Heat-Map View, WebSocket-API 8.3: Minor release ⢠JMC Core: Parser improvements ⢠JFR: Dependency view, Graph Pruning, JFR: Selectable attributes, ⢠Agent: bug fi xing
- 13. Java Mission Control Project Current release 8.3 Dependency View Graph pruning View Flameview Selectable Attributes
- 14. Java Flight Recorder under the hood Java Event API JVM Events Thread Local Buffers Events Global Bu ff ers Repository per 1s JFR Event Streaming (JEP 349): Continual Monitoring
- 15. JFR under the hood: Event - fundamental element ⢠Import âjdk.jfr.Eventâ ⢠Basic Element that caries valuable information EventID: Timestamp : when event was taken Duration: not always Thread ID: Thread where event has occurred StackTrace ID: Itâs optional referst to the StackTrace, default depth 64 Payload: custom information
- 16. Import jdk.jfr.Event; public class SampleEvent extends Event { //internal logic String message; } ⌠void someAdvanceLogic() { SampleEvent e = new SampleEvent(); e.message = âImportant Informationâ; e.begin(); // advanced logic e.end(); e.commit(); } ⌠JFR under the hood: Event
- 17. JFR under the hood: : Tuning up an Event Annotations: https://docs.oracle.com/en/java/javase/19/docs/api/jdk.jfr/jdk/jfr/class-use/MetadataDe fi nition.html Annotation Description Default @Name Automatically Set, Recommended pattern: org.com⌠Event Full path with Name: openvalue.SampleEvent @Label Short descriptive information @Category Category is present to the user @Threshold Default min duration fo the event to be included in the recording 0ns @StackTrace Include a stack-trace to the event TRUE @Enabled Is Event enabled by default con fi guration
- 18. JFR under the hood: : Tuning up an Event import jdk.jfr.Event import jdk.jfr.Label import jdk.jdf.Name @Name(âcom.openvalue.events.SampleEventâ) @Label(âSample Eventâ) class SampleEvent extends Event { @Label(âMessageâ) String name; @Label(âValueâ) int value; } Annotations: https://docs.oracle.com/en/java/javase/19/docs/api/jdk.jfr/jdk/jfr/class-use/MetadataDe fi nition.html
- 19. JFR under the hood: Performance ⢠Usage of Thread Local Bu ff ers ⢠Java Platform Optimisation ⢠Methods: INLINING, CODE ELIMINATION, SCALARIZATION ⢠What happens when event is enabled / disabled -XX:StartFlightRecording=filename=<RECORDING_FILE>.jfr,dumponexit=true,settings=profile
- 20. void someAdvanceLogic() { SampleEvent e = new SampleEvent(); e.message = âImportant Informationâ; e.begin(); // advanced logic e.commit(); } void commit() { // IF itâs not enabled -> NOT INTERESTING if(isEnabled()){ //now() reads CPU clock register, cheap check long duration = now() - startTime; if(duration > THRESHOLD) { if (shouldCommit()) { // Cheap - Thread local writes actuallyCommit(); } } } Mikeal Vidstedt presented quite neat pseudo-code that helps to understand to the commit() JFR under the hood: Event in Action
- 21. void someAdvanceLogic(){ // allocating event SampleEvent e = new SampleEvent(); e.begin(); -> INLINING => e.startTime = now(); -> e.startTime = <JVM intrinsic> // advanced logic // timestamp, likewise INLINING, implicit end() e.commit(); // JFR ENABLED STATE if(e.isEnabled()){ // perform additional checks and maybe actuallyCommit() } } JFR under the hood: Enabled
- 22. JFR under the hood: Disabled - part 1 void someAdvanceLogic() { SampleEvent e = new SampleEvent(); // INLINING from the previous slide e.startTime = <JVM intrinsic>; // advanced logic //INLINING if(false) { // result e.isEnabled() //perform additional checks //CODE ELIMINATION -> will be removed } }
- 23. JFR under the hood: Disabled - part 2 void someAdvanceLogic() { SampleEvent e = new SampleEvent(); // SCALARIZATION -> REMOVAL e.begin() 1. initial state: e.begin(); 2. INLINING => e.startTime = <JVM intrinsic>; 3. INLINING => long startTime = <JVM intrisic>; 4. CODE ELIMINATION => long startTime = <JVM intrisic>; REMOVAL //business logic }
- 24. JFR under the hood: Disabled - part 3 void someAdvanceLogic() { //business logic }
- 25. JFR: Start Recording # Starting a recording $ java -XX:StartFlightRecording ⌠# Starting Recording and Storing into the file $ java -XX:StartFlightRecording=filename=<FILE_NAME>.jfr # Starting Recording and dump on exit $ java -XX:StartFlightRecording=filename=<FILE_NAME>.jfr,dumponexit-true,settings=profile # Using jcmd command via PID to start recording $ jcmd <PID> JFR.start duration=30s filename=hotmethods_jcmd.jfr
- 26. JFR: Data Visualisation ⢠Command line tool avaliable from JDK 11 => jfr $jfr summary <JFR_file> $jfr print âjson <JFR_FILE> ⢠JFR GUI. (DEMO) ⢠Automated analysis ⢠Java Application => Thread, Memory, etc. ⢠Event Browser
- 28. DEMO: Hot-Methods - Events streaming
- 30. DEMO: Latency
- 31. DEMO: Java Platform Module Latency var threadPerTaskExecutor = Executors.newThreadPerTaskExecutor(threadFactory); var executor = Executors.newVirtualThreadPerTaskExecutor(); threadPerTaskExecutor.execute(() -> { while (active.get()){ executor.submit(new ComputableTask(counter)); } }) â˘
- 32. JFR: How to Get ⢠Clone: https://github.com/openjdk/jmc. => script build.sh ⢠AdoptOpenJDK: http://adoptopenjdk.net/jmc ⢠Azul: https://www.azul.com/products/zulu-mission-control ⢠RedHat: distributes as RPMs in Fedora and RHEL ⢠Oracle: https://www.oracle.com/java/technologies/jdk-mission-control.html JMC-JVM-LANG Tutorial: https://github.com/mirage22/jmc-jvm-lang-tutorial JFR-Tutorial: https://github.com/thegreystone/jmc-tutorial
- 33. Q / A Thank YOU ! twitter: @miragemiko gitlab:@mirage22 DEMOS: https://github.com/mirage22/jmc-jvm-lang-tutorial
- 34. References: ⢠Project Amber: https://openjdk.org/projects/amber/ ⢠Project Loom: https://openjdk.org/projects/loom/ ⢠JFR Project: https://github.com/openjdk/jmc ⢠OpenJDK: https://openjdk.org/ ⢠JEP-349 JFR Event Steaming: https://openjdk.org/jeps/349 ⢠foojay.io: https://foojay.io/today/author/miro-wengner/ ⢠OpenValue Blog: https://openvalue.blog/ Book In Progress: Practical Design Patterns for Java Developers [PACKT]