Better Understanding through Bytecode

Outline

• JVM Runtime
  • Stacks rule everything around me
    • Threads and the call stack
    • Execution stack per method
  • Bytecodes
    • javap
    • Anatomy of a bytecode (optional params, actually bytes)
    • load
    • store
    • Constant pool
    • new/dup/
    • get/putfield
    • if/goto (look ma, no loops!)
    • invoke methods
• Concurrency
  • We can see the interleaving between threads
• Tail Call
  • Top level functions in Kotlin, but still need a class in bytecode!
  • GOTO makes everything better
• Coroutines
  • Like before, lots extra generated on our behalf!
  • State machine for each of our steps
  • Following method calls

Resources

• Java Virtual Machine Spec: Instruction Set
• Fantastic Bytecodes & How To Interpret Them by Ben Evans