Question

任何人都可以解释一下这些python字典，列表变量存储在内存中。我知道在python内存管理是使用堆和堆栈完成的。但是我真的找不到关于在创建字典变量时如何分配内存的简单解释，它是在堆栈框架还是堆空间中创建的？

Answer 1

好吧，让我们看一下源代码吧！

来自：https://github.com/python/cpython/blob/master/Objects/dictobject.c

static PyObject *
new_dict(PyDictKeysObject *keys, PyObject **values)
{
    PyDictObject *mp;
    ...
        mp = PyObject_GC_New(PyDictObject, &PyDict_Type);
    ...
    return (PyObject *)mp;
}

因此，似乎使用dict

分配了新的PyObject_GC_New()对象

来自：https://github.com/python/cpython/blob/master/Doc/c-api/gcsupport.rst#id9

.. c:function:: TYPE* PyObject_GC_New(TYPE, PyTypeObject *type)

   Analogous to :c:func:`PyObject_New` but for container objects with the
   :const:`Py_TPFLAGS_HAVE_GC` flag set.

来自：https://github.com/python/cpython/blob/master/Objects/object.c

PyObject *
_PyObject_New(PyTypeObject *tp)
{
    PyObject *op;
    op = (PyObject *) PyObject_MALLOC(_PyObject_SIZE(tp));
    if (op == NULL)
        return PyErr_NoMemory();
    return PyObject_INIT(op, tp);
}

来自：https://github.com/python/cpython/blob/master/Objects/obmalloc.c

#define MALLOC_ALLOC {NULL, _PyMem_RawMalloc, _PyMem_RawCalloc, _PyMem_RawRealloc, _PyMem_RawFree}
#ifdef WITH_PYMALLOC
#  define PYMALLOC_ALLOC {NULL, _PyObject_Malloc, _PyObject_Calloc, _PyObject_Realloc, _PyObject_Free}
#endif

#define PYRAW_ALLOC MALLOC_ALLOC
#ifdef WITH_PYMALLOC
#  define PYOBJ_ALLOC PYMALLOC_ALLOC
#else
# define PYOBJ_ALLOC MALLOC_ALLOC
static PyMemAllocatorEx _PyObject = PYOBJ_ALLOC;
...

void *
PyObject_Malloc(size_t size)
{
    /* see PyMem_RawMalloc() */
    if (size > (size_t)PY_SSIZE_T_MAX)
        return NULL;
    return _PyObject.malloc(_PyObject.ctx, size);
}

我认为现在可以安全地假设这些会调用malloc，calloc，realloc和free。

此时，这不再是一个python问题，但答案是操作系统依赖于malloc是在堆栈还是堆上分配。

字典变量如何存储在内存中？

1 个答案: