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Commit ускоривший Python 2.7 на 30%
иновое в Python 3.5
@sapronovalex92
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Александр Сапронов:
Python 2.7.11Vamsi Parasa of the Server Scripting Languages Optimization team at Intel posted
a patch to change the switch statement that executes Python bytecode in the CPython interpreter to use computed gotos instead.
(http://article.gmane.org/gmane.comp.python.devel/153401)
Python 2.7.11Vamsi Parasa of the Server Scripting Languages Optimization team at Intel posted
a patch to change the switch statement that executes Python bytecode in the CPython interpreter to use computed gotos instead.
(http://article.gmane.org/gmane.comp.python.devel/153401)
computed gotoВ отличие от switch-case: Не производит граничных проверок
#define OP_HALT 0x0
#define OP_INC 0x1
int interp_switch(unsigned char* code, int initval) {
int pc = 0;
int val = initval;
while (1) {
switch (code[pc++]) {
case OP_HALT:
return val;
case OP_INC:
val++;
break;
default:
return val;
}
}
}
computed gotoВ отличие от switch-case: Не производит граничных проверок
#define OP_HALT 0x0
#define OP_INC 0x1
int interp_switch(unsigned char* code, int initval) {
int pc = 0;
int val = initval;
while (1) {
switch (code[pc++]) {
case OP_HALT:
return val;
case OP_INC:
val++;
break;
default:
return val;
}
}
}
int interp_cgoto(unsigned char* code, int initval) {
static void* dispatch_table[] = {&&do_halt, &&do_inc};
#define DISPATCH() goto *dispatch_table[code[pc++]]
int pc = 0;
int val = initval;
DISPATCH();
while (1) {
do_halt:
return val;
do_inc:
val++;
DISPATCH();
}
}
computed gotoВ отличие от switch-case: CPU может лучше прогнозировать ветвления
Подробно про computed goto:
http://eli.thegreenplace.net/2012/07/12/computed-goto-for-efficient-dispatch-tables
Модуль предсказания переходов:устройство, входящее в состав микропроцессоров, имеющих
конвейерную архитектуру, предсказывающее, будет ли выполнен условный переход в исполняемой программе.
Новое в Python 3.5 - PEP 478● PEP 441 , improved Python zip application support
● PEP 448 , additional unpacking generalizations
● PEP 461 , "%-formatting" for bytes and bytearray objects
● PEP 465 , a new operator ("@") for matrix multiplication
● PEP 471 , os.scandir(), a fast new directory traversal function
● PEP 475 , adding support for automatic retries of interrupted system calls
● PEP 479 , change StopIteration handling inside generators
● PEP 484 , the typing module, a new standard for type annotations
● PEP 485 , math.isclose(), a function for testing approximate equality
● PEP 486 , making the Widnows Python launcher aware of virtual environments
● PEP 488 , eliminating .pyo files
● PEP 489 , a new and improved mechanism for loading extension modules
● PEP 492 , coroutines with async and await syntax
PEP 448 - additional unpacking generalizations
>>> print(*[1], *[2], 3)1 2 3>>> dict(**{'x': 1}, y=2, **{'z': 3}){'x': 1, 'y': 2, 'z': 3}>>> *range(4), 4(0, 1, 2, 3, 4)>>> [*range(4), 4][0, 1, 2, 3, 4]
>>> {*range(4), 4}{0, 1, 2, 3, 4}>>> {'x': 1, **{'y': 2}}{'x': 1, 'y': 2}>>> {'x': 1, **{'x': 2}}{'x': 2}>>> {**{'x': 2}, 'x': 1}{'x': 1}
PEP 484 - the typing module, a new standard for type annotations
def greeting(name: str) -> str: return 'Hello ' + name
from typing import *
T = TypeVar('T')
def filter(function: Optional[Callable[[T], Any]], iterable: Iterable[T]) -> Iterator[T]: ...
Было
Стало
PEP 492 - coroutines with async and await syntax
async def read_data(db): pass
async def read_data(db): data = await db.fetch('SELECT ...')
Новые ключевые слова: async и await
11
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@py_nsk
PyNSK контакты: Мои контакты:
ru.linkedin.com/in/alexsapronov
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