Memory management / garbage collection:

Memory management (garbage collection)

• Object Category:

  • Fixed-length: int / float

     _PyObject_HEAD_EXTRA #define \ struct _Object * _ob_next; \ struct _Object * _ob_prev; typedef struct _Object { _PyObject_HEAD_EXTRA   // configured for bidirectional linked list Py_ssize_t ob_refcnt; // reference counter struct _typeobject * ob_type; // Type } the PyObject;
         
         
     
     
         
         
         
     

  • A plurality of elements: str / list / dict / set / tuple

     typedef struct {
         PyObject ob_base;
         Py_ssize_t ob_size; /* Number of items in variable part */
     } PyVarObject;

• Memory management

  • Based reference counter

     def func ():    each created object, the open space in the memory, the reference counter by default. 1;    a = 123    create a variable opening up a point to the original memory, the reference count + 1'd;    B = a FUNC ( ) when the reference counter is 0, it indicates that the garbage can be recycled.
     
     
     
     
     
     
     
     
     
     

  • Circulation problems cited

     When an object is created for the Python str / list / dict / set / tuple class, the object will be placed in a doubly linked list. 
     A = "asdf" 
     B = [11,22] 
     C = { 'K1': 123} If the object list 700 is reached, the elements on all the doubly linked list is scanned, if there is a circular reference, the two are -1, and finally scanned, all the elements of the list into two: 1. the reference counter 0 objects recovered. 2. the object reference counter is not 0, it will be a doubly linked list into another (a total of three lists).