адреса ячеек памяти/переменные/jvm

[p4p4]

Можно ли получить информацию об адресе ячейки памяти,в которой хранится переменная?
Если да, то как это сделать(существуют ли готовые решения - тулзы?), какие ограничения существуют?(как обойти данные ограничения?)
если такое возможно реализовать, то как в случае с динамической аллокацией памяти быть? - так называемая "хронология" записи может быть отсележна - куда копать в сторону сборщика?
сборщик не логирует работу с датой в памяти, какими средствами отследить изменения ?

 

[shrekushka]

Most GCs move objs in memory (compacting, defrag heaps) for perf. If Java exposed stable obj addrs, that would constrain the GC’s ability to move shit around. JIT compiler + opts will eliminate/rearrange objs + local vars in registers, on the stack etc. The notion of a single “memory address” will be meaningless from the viewpoint of these optimizations.
There is no standard Java log that says “Obj X was moved from addr A to addr B at time T.”

JOL uses HotSpot internals/instr to "estimate" obj layout + addrs: how fields are laid out + approx. offset of objs relative to some base addr.
JVMTI is a "native" interface: “official” low-level interface for debuggers, profilers.

GitHub - openjdk/jol: https://openjdk.org/projects/code-tools/jol

https://openjdk.org/projects/code-tools/jol. Contribute to openjdk/jol development by creating an account on GitHub.

github.com

Java Virtual Machine Tool Interface (JVM TI)

 

[p4p4]

Most GCs move objs in memory (compacting, defrag heaps) for perf. If Java exposed stable obj addrs, that would constrain the GC’s ability to move shit around. JIT compiler + opts will eliminate/rearrange objs + local vars in registers, on the stack etc. The notion of a single “memory address” will be meaningless from the viewpoint of these optimizations.
There is no standard Java log that says “Obj X was moved from addr A to addr B at time T.”

JOL uses HotSpot internals/instr to "estimate" obj layout + addrs: how fields are laid out + approx. offset of objs relative to some base addr.
JVMTI is a "native" interface: “official” low-level interface for debuggers, profilers.

GitHub - openjdk/jol: https://openjdk.org/projects/code-tools/jol

https://openjdk.org/projects/code-tools/jol. Contribute to openjdk/jol development by creating an account on GitHub.

github.com

Java Virtual Machine Tool Interface (JVM TI)

thx mate!