The only storage area in the JVM where GC and oom will not occur

PC register

JVM Medium PC Registers are for physics PC An abstract simulation of registers . Used to store the address pointing to the next instruction , It is also the instruction code to be executed . The execution engine reads the next instruction .
Very small memory footprint , The fastest . Thread private .
The only one who didn't OOM Region .

1.PC Why are registers set to thread private ？

cpu I'll keep switching tasks , This will inevitably lead to frequent interruption and recovery . In order to accurately record the current bytecode instruction address that each thread is executing , So each thread is assigned a PC register .

2. Use PC What's the use of register storage bytecode to specify address ？

CPU You need to keep switching threads , After switching back , Need to know where to proceed .

3. Why use PC Register records the execution address of the current thread ？

JVM Bytecode interpreter needs to be changed PC Register to determine what kind of bytecode instruction should be executed next .