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javajit

JIT compiler and execution

I'm confused with JIT compiler,

  1. What is JIT compiler?
  2. JIT compiler compiles byte codes before each execution or each time JVM loads?
Solution

  • JIT stands for "Just In Time". It's a compiler that translates Java bytecode to native machine code as your program runs.

    Sun's JIT does not compile all your bytecode up front each time you run a Java program; it contains some very sophisticated logic to decide when to compile parts of the bytecode, one of the criteria it uses is how often the code is executed.

    See Just-in-time compilation and HotSpot (Wikipedia) for more details.