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[Python] lru_cache
0. 개요
LRU(Last Recently Used) 는 운영체제 OS에서 메모리 관리에서 Page 교체에서 사용되는 알고리즘 중 하나로
가장 오랫동안 사용하지 않은 것을 교체하는 방식입니다
Python에서는 @lru_cache 로 데코레이터로 기능을 제공해주고 있습니다.
1. 기대 효과
Memorization으로 추가 계산 감소CPU-Bound감소
2. Sample Code
lru_cache데코레이터는 실행 함수에 3가지 함수를 추가합니다.- 사용 방법은
@lru_cache(maxsize=128, typed=False)maxsize: lru_cache에 입력된 호출 기억하고 있을 크기typed: 고정 타입 사용 유무
cache_parameters(): 데코레이터 입력 값cache_info(): 캐시 정보cache_clear(): 캐시 지우기
- 사용 방법은
import random
from decimal import Decimal
from functools import lru_cache
from random import choice
class Message:
HTTP_SUCCESS = (200, "Success")
HTTP_CREATED = (201, "Created")
HTTP_BAD_REQUEST = (400, "Bad request")
HTTP_NOT_FOUND = (404, "Not found")
USER_NOT_FOUND = (1000, "User not found")
USER_EMAIL_EXIST = (1010, "User email already exist")
@lru_cache
def get_message():
return Message
def rand() -> str:
return choice([
"HTTP_SUCCESS", "HTTP_CREATED", "HTTP_BAD_REQUEST", "HTTP_NOT_FOUND",
])
@lru_cache(maxsize=5, typed=True)
def calc_something(a: int, b: int) -> int:
return a * b
class Stock:
def __init__(self, name: str, price: Decimal, discount: Decimal):
self.name = name
self.price = price
self.discount = discount
@lru_cache(typed=True)
def calc_pay_price(price: Decimal, discount: Decimal) -> Decimal:
return price - discount
if __name__ == '__main__':
print("### Config, Message 등 고정 값(?) 같은 것들")
for _ in range(10):
print(getattr(get_message(), rand()), '\t\t', get_message.cache_info())
print("# 이후에도 메모지에이션 되어 있음")
print(get_message().HTTP_SUCCESS, '\t\t', get_message.cache_info())
print(get_message().USER_NOT_FOUND, '\t\t', get_message.cache_info())
print("\n\n### 단순 계산")
for _ in range(10):
rand_int = random.randint(0, 10)
print(calc_something(rand_int, rand_int), '\t\t', calc_something.cache_info())
print("\n\n### 엔티티 계산")
stocks = [
Stock("Product-1", Decimal(100), Decimal(10)),
Stock("Product-2", Decimal(200), Decimal(10)),
Stock("Product-3", Decimal(300), Decimal(10)),
Stock("Product-4", Decimal(100), Decimal(10)),
Stock("Product-5", Decimal(400), Decimal(10)),
Stock("Product-6", Decimal(200), Decimal(10)),
]
for stock in stocks:
print(calc_pay_price(stock.price, stock.discount), "\t\t", calc_pay_price.cache_info())3. Sample Code Result
### Config, Message 등
(200, 'Success') CacheInfo(hits=0, misses=1, maxsize=128, currsize=1)
(200, 'Success') CacheInfo(hits=1, misses=1, maxsize=128, currsize=1)
(400, 'Bad request') CacheInfo(hits=2, misses=1, maxsize=128, currsize=1)
(400, 'Bad request') CacheInfo(hits=3, misses=1, maxsize=128, currsize=1)
(201, 'Created') CacheInfo(hits=4, misses=1, maxsize=128, currsize=1)
(404, 'Not found') CacheInfo(hits=5, misses=1, maxsize=128, currsize=1)
(404, 'Not found') CacheInfo(hits=6, misses=1, maxsize=128, currsize=1)
(200, 'Success') CacheInfo(hits=7, misses=1, maxsize=128, currsize=1)
(200, 'Success') CacheInfo(hits=8, misses=1, maxsize=128, currsize=1)
(404, 'Not found') CacheInfo(hits=9, misses=1, maxsize=128, currsize=1)
# 이후에도 메모지에이션 되어 있음
(200, 'Success') CacheInfo(hits=10, misses=1, maxsize=128, currsize=1)
(1000, 'User not found') CacheInfo(hits=11, misses=1, maxsize=128, currsize=1)
### 단순 계산
4 CacheInfo(hits=0, misses=1, maxsize=5, currsize=1)
16 CacheInfo(hits=0, misses=2, maxsize=5, currsize=2)
0 CacheInfo(hits=0, misses=3, maxsize=5, currsize=3)
4 CacheInfo(hits=1, misses=3, maxsize=5, currsize=3)
0 CacheInfo(hits=2, misses=3, maxsize=5, currsize=3)
81 CacheInfo(hits=2, misses=4, maxsize=5, currsize=4)
0 CacheInfo(hits=3, misses=4, maxsize=5, currsize=4)
100 CacheInfo(hits=3, misses=5, maxsize=5, currsize=5)
9 CacheInfo(hits=3, misses=6, maxsize=5, currsize=5)
9 CacheInfo(hits=4, misses=6, maxsize=5, currsize=5)
### 엔티티 계산
90 CacheInfo(hits=0, misses=1, maxsize=128, currsize=1)
190 CacheInfo(hits=0, misses=2, maxsize=128, currsize=2)
290 CacheInfo(hits=0, misses=3, maxsize=128, currsize=3)
90 CacheInfo(hits=1, misses=3, maxsize=128, currsize=3)
390 CacheInfo(hits=1, misses=4, maxsize=128, currsize=4)
190 CacheInfo(hits=2, misses=4, maxsize=128, currsize=4)Ref
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