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Version: 1.0

java

Garbage Collector​

  • Free the heap by destroying the objects that don't contain a reference
  • Steps
    • Mark objects
    • Sweep dead objects
    • Compact memory

Young generation​

  • -Xmn: Young generation size
  • -Xms: initial size of the heap
  • -Xmx: maximum size of the heap

Permanent generation​

  • XX:PermGen and -XX:MaxPermGen initial and maximum size of permanent generation

GC types​

  • Serial GC
    • Useful for small app running in single thread
    • The garbage collection occurs in one thread, and the compaction is performed after the collection if finished

Static class​

JVM​

  • Class loader
    • Loading
    • Linking
      • Verify
      • Prepare
      • Resolve
    • Initialization
  • Runtime data area
  • Execution engine: convert byte code to machine code
    • Interpreter
    • JIT compiler: complies bytes code to native codes. Native code will be used for repetead methods calls
    • Profiler
    • CG