PyObject
contents
related file
- cpython/Include/object.h
- cpython/Include/cpython/object.h
- cpython/Python/ceval.c
- cpython/Include/ceval.h
- cpython/Python/pythonrun.c
memory layout
this is the layout of PyObject, it’s the basic part of every other python object
every object in python can be cast to PyObject, i.e, list, tuple and etc
PyObject_HEAD_EXTRA is the head of the double linked list, it’s used for keeping track in Garbage Collection
ob_refcnt stores reference count of the current object, it’s also used in Garbage Collection
ob_type is a pointer to it’s type object, i.e, type("abc") ===> str, "abc" is the PyObject, and ob_type in the PyObject will points to str
overview
whenever you execute a python program for a .py file, the compile phase will translate the human readable source code to a form called python bytecode
the pyc file will be generated if necessary, and the interpreter phase will start the main loop, execute the bytecode in the pyc file line by line
the compiled pyc file will not boost the run time of the program, instead, the load time of the program will be faster because it doesn’t need to generate pyc file again
according to pep-3147, after python 3.3, pyc file will only be generated in the import mechanism, and pyc file will exists under the __pycache__ directory
ceval
the main loop of the interpreter is defined in cpython/Python/ceval.c
main_loop:
for (;;) {
// jump to fast_next_opcode if necessary
// check for signal hndler/async io handler
// drop gil if needed
fast_next_opcode:
switch (opcode) {
/* ... */
}
}
we can draw the procedure
intepreter and thread
this is the defination of PyInterpreterState
this is the defination of PyThreadState
if we have two thread currently running
