我的知识结构(20190927)

Posted 2020-11-16 tutoutu

我的知识结构

今天面试，感受颇多。
发现自己已经习惯把记不得当作借口，趁此机会，整理一下自己的知识体系。

Programming

JVM

JVM Specification

• Field
  • Field is owned by class who declared it.
  • Resolution: self -> superinterfaces -> superclass
• Invoke bytecode
  • invokevirtual
    • Compile time method slot
  • invokestatic
  • invokespecial
    • instance initialization methods
    • methods of the current class
    • methods of its supertypes
  • invokeinterface
  • invokedynamic
    • lang.invoke.CallSite

JRE

• Map
  • util.HashMap
    • 读源码
    • Hash Table
      • Resize for 2× capacity
      • threshold = loadFactor × capacity
    • Linked List Node or Red-Black Tree Node
      • Threshold 8 and 6
      • Using instanceof to divide
  • util.TreeMap
    • Red-Black Tree
  • util.concurrent.ConcurrentHashMap
    • like CopyOnWriteArrayList, using CAS
    • Use #transferIndex as optimistic lock
    • Linked List Node or Red-Black Tree Node
      • Threshold 8 and 6
      • Using ~.Node#hash to divide
    • Forwarding Node and Reservation Node
      • 待续

Hotspot VM

• 内存布局
  • Memory using "malloc, realloc, free"
    • Unsafe ability
    • Manual memory management
    • Using for IO
  • 以下内容待验证
    • MetaSpace
    • Heap
      • Old Generation
      • Young Generation
        • Eden Space
        • Suvrvivor1/2