Memory management
本文所描述的memory management是指process级别的memory management，而不是OS kernel级别的memory management，关于OS kernel的memory management，参见工程Linux-OS。process级别的memory management主要由programming language的实现决定，目前有如下两种方式：
维基百科Memory management
Memory management is a form of resource management applied to computer memory. The essential requirement of memory management is to provide ways to dynamically allocate portions of memory to programs at their request, and free it for reuse when no longer needed. This is critical to any advanced computer system where more than a single process might be underway（运行中） at any time.
Several methods have been devised that increase the effectiveness of memory management. Virtual memory systems separate the memory addresses used by a process from actual physical addresses, allowing separation of processes and increasing the size of the virtual address space beyond the available amount of RAM using paging or swapping to secondary storage. The quality of the virtual memory manager can have an extensive effect on overall system performance.
Details
Memory management within an address space is generally categorized as either automatic memory management, usually involving garbage collection, or manual memory management.
NOTE:
automatic memory management和manual memory management是当前programming language implementation所采用的两种主流方式，后面会对此进行展开。
Dynamic memory allocation
See also: C dynamic memory allocation
Implementations
Fixed-size blocks allocation
Main article: Memory pool
Buddy blocks
Further information: Buddy memory allocation
Slab allocation
Main article: Slab allocation
Stack allocation
Main article: Stack-based memory allocation
Automatic variables
Main article: Automatic variable
In many programming language implementations, all variables declared within a procedure (subroutine, or function) are local to that function; the runtime environment for the program automatically allocates memory for these variables on program execution entry to the procedure, and automatically releases that memory when the procedure is exited. Special declarations may allow local variables to retain values between invocations of the procedure, or may allow local variables to be accessed by other procedures. The automatic allocation of local variables makes recursion possible, to a depth limited by available memory.
Garbage collection
Main article: Garbage collection (computer science)