Memory Management

  • Memory Management

  • https://dzone.com/articles/java-memory-management

  • http://tutorials.jenkov.com/java-concurrency/java-memory-model.html

  • https://www.journaldev.com/4098/java-heap-space-vs-stack-memory

  • http://www.baeldung.com/java-initialization

  • https://examples.javacodegeeks.com/java-memory-management/

  • https://youtu.be/LCSqZyjBwWA The Java Memory Model - The Basics

  • https://youtu.be/bspS-uTK0IM Understanding JVM Memory, Heap, Garbage Collection and Monitoring the JVM | Tech Primers

  • https://www.youtube.com/watch?v=JLFjY6Ixct8 A Visual Introduction to Inner-Workings of the JVM - Douglas Hawkins

  • https://opensource.com/article/22/4/jvm-parameters-java-developers

  • https://www.digitalocean.com/community/tutorials/java-jvm-memory-model-memory-management-in-java

  • https://docs.oracle.com/javase/8/docs/technotes/guides/vm/gctuning/

  • https://stackoverflow.com/questions/36465192/guidelines-to-set-metaspacesize-java-8

  • https://www.baeldung.com/java-permgen-metaspace performance https://www.dynatrace.com/resources/ebooks/javabook/

Debugging

  • https://mydeveloperplanet.com/2018/11/14/how-to-solve-your-java-performance-problems-part-1/

Heap and stack

  • https://stackify.com/java-heap-vs-stack/

  • https://www.journaldev.com/4098/java-heap-space-vs-stack-memory

  • https://dzone.com/articles/stack-vs-heap-understanding-java-memory-allocation

  • https://gribblelab.org/CBootCamp/7_Memory_Stack_vs_Heap.html

Defintions

  • Shallow heap

    • is the memory consumed by one object. The actual memory consumed by one object depends on the underlying architecture.

  • Retained Heap of an object

    • is the sum of shallow sizes of all objects in the retained set of that object.

  • Retained set of an object

    • is the set of objects, which would be removed by GC when that particular object is garbage collected.

  • A heap dump is a snapshot of the heap memory of a Java process at a given time.

    • The snapshot mainly consists of Java objects and classes.

GArbage collection

  • https://self-learning-java-tutorial.blogspot.co.uk/2014/07/garbage-collection.html

  • https://stackify.com/what-is-java-garbage-collection/

  • https://roytuts.com/what-is-the-purpose-of-garbage-collection-in-java/

  • https://www.perfmatrix.com/how-does-garbage-collector-work/

  • https://stackoverflow.com/questions/25885826/java-gcold-generation-becomes-larger-and-larger-and-cannot-be-reclaimed

  • https://stackoverflow.com/questions/34670751/why-gc-on-old-generation-takes-longer-than-gc-on-young-generation

  • https://backstage.forgerock.com/knowledge/kb/article/a75965340

  • https://www.papertrail.com/solution/tips/7-problems-to-look-out-for-when-analyzing-garbage-collection-logs/

  • https://backstage.forgerock.com/knowledge/kb/article/a35746010

  • https://dzone.com/articles/understanding-garbage-collection-log

  • https://docs.oracle.com/javase/8/docs/technotes/guides/vm/gctuning/cms.html

  • https://www.oracle.com/technetwork/tutorials/tutorials-1876574.html

  • https://devm.io/java/garbage-collection-g1-172816

Memory leaks

  • https://self-learning-java-tutorial.blogspot.co.uk/2014/07/what-is-memory-leak-in-java.html

  • https://stackify.com/memory-leaks-java/

  • https://www.baeldung.com/java-memory-leaks

  • https://dzone.com/articles/how-memory-leaks-happen-in-java-apps

  • https://www.toptal.com/java/hunting-memory-leaks-in-java

  • https://www.dynatrace.com/news/blog/how-to-identify-a-java-memory-leak/

  • https://dzone.com/articles/what-to-do-about-java-memory-leaks-tools-fixes-and

  • https://dzone.com/articles/how-to-find-and-fix-memory-leaks-in-your-java-appl

https://github.com/makersacademy/java_intro/blob/master/chapter0-What-is-Java/terminology.md

Heap dumps

  • https://www.javacodegeeks.com/2019/10/7-options-to-capture-java-heap-dumps.html

Graphs

  • saw tooth graph

    • https://stackoverflow.com/questions/47766884/why-does-heap-memory-usage-graph-look-like-this

  • https://docs.azul.com/zing/UsingZing_GCLogAnalyser_HeapUseGraphs.htm

Jmx

  • https://stackify.com/asynchronous-programming-easier-think/

  • https://self-learning-java-tutorial.blogspot.com/2018/07/jmx-tutorial.html

Thread dumps

  • https://self-learning-java-tutorial.blogspot.com/2018/08/working-with-jcmd-command.html

Jstat

  • https://www.javacodegeeks.com/2019/11/jstat-analysis.html

Benchmarking

  • Use Benchmarking to find out current performance

    • used to decide where to optimise

  • Benchmarking and microbenchmarking on the JVM is hard

    • need to consider the following:

      • warm-up

      • HotSpot compilation

      • code optimizations like inlining and dead code elimination

      • multithreading

      • consistency of measurement

      • and more

  • Tooling

    • https://github.com/openjdk/jmh

  • JVM visualisation tools

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