Java Garbage Collection

• G1 GC
• GC 옵션은 어떤 상황에서든 명시적으로 지정하는게 좋다.
  • 메모리가 1792mb 이하이면 Serial GC로 기본 지정된다. 이는 심각한 성능저하를 일으킨다.
  • https://twitter.com/brunoborges/status/1499114848516329472?s=20&t=MA20XuqUuG50dnOvqXIXqw

• Java 11 GC Tuning
• Java 8 GC Tuning

• Java GC 튜닝 - 기계인간 John Grib
• Java SE 6 HotSpot[tm] Virtual Machine Garbage Collection Tuning
• Java 8 GC Tuning
• How Garbage Collection differs in the three big JVMs
• The Top Java Memory Problems – Part 1
• HelloWorld » Garbage Collection 모니터링 방법
• Getting Started with the G1 Garbage Collector
• Java GC 로그 분석
• How to tune java gc
• hello world » Java Garbage Collection 한국어 설명
• hello world » Garbage Collection 모니터링 방법
• hello world » Garbage Collection 튜닝
• hello world » Java Reference와 GC
• Garbage Collectors - Serial vs. Parallel vs. CMS vs. G1 (and what’s new in Java 8) | Takipi Blog
• 7 Things You Thought You Knew About Garbage Collection – and Are Totally Wrong
• JVM GC Options
• JVM Tuning – Garbage Collection
• GC Easy Web GC Log Analyzer
• Garbage Collection 튜닝
• Verbose Garbage Collection in Java | Baeldung
• Minimize Java Memory Usage with the Right Garbage Collector
• Java RAM Usage in Containers: 5 Tips Not to Lose Memory
• 5 Steps to Stop Overpaying for Java Cloud Hosting Resources

• Garbage Collection 모니터링 방법
• GC 상태 보기
• -verbose:gc
  • -XX:+PrintGCDetails
  • -XX:+PrintGCTimeStamps
  • -XX:+PrintHeapAtGC
  • -XX:+PrintGCDateStamps (from JDK 6 update 4) 이 옵션은 사용하지 말고 GC 시간을 정리해보여주는 스크립트 사용할것.
  • -XX:+PrintReferenceGC
  • -XX:+PrintGCApplicationStoppedTime
  • -XX:+PrintClassHistogramAfterFullGC
  • -XX:+PrintClassHistogramBeforeFullGC
• -Xloggc:<file> : GC 로그를 file로 남긴다.
• -XX:+HeapDumpAfterFullGC
• -XX:+HeapDumpBeforeFullGC
• -XX:+HeapDumpOnOutOfMemoryError
• -XX:HeapDumpPath=<path>
  • -XX:-TraceClassUnloading -XX:-TraceClassLoading : class loading/unloading 로깅
• HPJMeter verbose:gc결과 분석
  • gc 로그에 PrintGCDateStamps 이 옵션으로 인한 날짜 정보가 있으면 날짜 관련 부분을 지워야한다.
• GCViewer Java 6/7 지원, PrintGCDateStamps지원.
• Human readable JVM GC timestamps – The Server Labs Blog
• robertmaldon: More human-friendly Java GC timestamps
• Garbage Collector Log Analysers
• Understanding G1 GC Log Format
• microsoft/gctoolkit: Tool for parsing GC logs

• Rolling Java GC Logs
• vmoptions 참조
• -XX:+UseGCLogFileRotation : 기본 false, 지정만 하면 바로 true.
• -XX:NumberOfGCLogFiles : 기본 0. Rotate 안 함.
• -XX:GCLogFileSize : 기본 0. Rotate 안 함. 최소 8k 이상.

java -Xloggc:gc.log -verbose:gc -XX:+PrintGCDetails -XX:+PrintGCDateStamps -XX:+PrintGCTimeStamps \
 -XX:+UseGCLogFileRotation -XX:NumberOfGCLogFiles=5 -XX:GCLogFileSize=128K

• Introducing Microsoft GCToolkit | Java at Microsoft