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Java / JVM Architecture (Java21) Interview questions

What is the Execution Engine in JVM?

The Execution Engine is the component that actually runs the bytecode sitting in the runtime data areas, turning it into real behavior on the CPU.

It is made up of three cooperating parts: an Interpreter that executes bytecode instruction by instruction, a JIT compiler that compiles frequently run ("hot") bytecode into native machine code, and the Garbage Collector that reclaims memory from unreachable objects.

The interpreter and JIT compiler work together rather than as alternatives - the HotSpot JVM starts by interpreting, then swaps in compiled native code for methods it identifies as hot.

The Execution Engine is made up of:
HotSpot begins executing a method by:

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