Hostpot virtual machine runtime data area memory model
The white part is the shared memory of all threads when the JVM is running
The blue part is the thread exclusive memory
A shared memory
1 Method area characteristics
Used to store class information, constants, and static variables loaded by the virtual machine
The jvm specification describes it as a logical part of the heap, but it is different. Alias No-Heap non-heap
GC seldom recycles this part of memory because it has little effect
The main GC recovery target is this part of the runtime constant pool (String.intern and other methods will generate runtime constants) and the type is written in
2 Heap characteristics
Store object instances, almost all object memory is allocated here (with the development of techniques such as escape analysis scalar replacement on the stack , not all object instances are allocated on the heap)
GC's main recycling goal is divided into the new generation and the old generation in order to facilitate the storage of the heap memory
The heaped memory can be configured to be expandable and controlled by -xmx -xms
Two-thread private memory area
1 Program counter
A small area guides the thread code execution order
2 virtual machine stack
Life cycle is the same as thread
Store local variable table and other information
Local variable table : stores various data types known at compile time, and object references
3 Local method stack
Different from the virtual machine stack serving native methods
Three other memory areas
Direct memory: use native method native to directly allocate off-heap memory
