线程池

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
from concurrent.futures import ThreadPoolExecutor

def main(url):
	pass

Pool = ThreadPoolExecutor(max_workers=10)
list(Pool.map(main, links))

# 传入多个参数
def add(x, y):
    return x + y

nums = [(1, 2), (3, 4), (5, 6)]

with ThreadPoolExecutor(max_workers=3) as executor:
    results = executor.map(add, *zip(*nums))

# 传参为空
import threading
for i in range(10):
    threading.Thread(target=main).start()

进程池

1
2
3
4
5
6
7
8
9
10
11
12
13
import multiprocessing as mp

pool = mp.Pool(processes=10)
pool.map(main, url_lst)

# 传入多个参数
def func(arg1, arg2):
    print(arg1, arg2)

kwargs = {'arg1': 'hello', 'arg2': 'world'}
p = multiprocessing.Process(target=func, kwargs=kwargs)
p.start()
# p.join()  会堵塞住

多线程

适用于IO密集型任务

基本使用和实现效果

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
import threading as td

import sys
import time

def threadJobOne():
    # 获取当前函数名
    print(td.current_thread())
    func_name = sys._getframe().f_code.co_name
    print("start ", func_name)
    time.sleep(3)
    print("end ", func_name)


def threadJobTwo():
    print(td.current_thread())
    func_name = sys._getframe().f_code.co_name
    print("start ", func_name)
    time.sleep(2)
    print("end ", func_name)


def threadJobThree():
    print(td.current_thread())
    func_name = sys._getframe().f_code.co_name
    print("start ", func_name)
    time.sleep(1)
    print("end ", func_name)


if __name__ == "__main__":
    t1 = td.Thread(target=threadJobOne, name="T1")
    t2 = td.Thread(target=threadJobTwo, name="T2")
    t3 = td.Thread(target=threadJobThree, name="T3")
    t1.start()
    t2.start()
    t3.start()
    print("已激活线程数：", td.active_count())  # 已激活线程数
    print(td.enumerate())  # 列举全部线程名
    
'''
输出：
<Thread(T1, started 17812)>
start  threadJobOne
<Thread(T2, started 14676)>
start  threadJobTwo
<Thread(T3, started 31576)>
start  threadJobThree
已激活线程数：4
[<_MainThread(MainThread, started 18304)>, <Thread(T1, started 17812)>, <Thread(T2, started 14676)>, <Thread(T3, started 31576)>]

end  threadJobThree
end  threadJobTwo
end  threadJobOne
'''

threadJobThree 所在的线程是最后启动的，但因为耗时最短，所以是最先完成

锁和传参

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
import threading as td

import time


lock = td.Lock()  # 主要用于解决全局变量的问题
lock.acquire()  # 锁住当前线程
lock.release()  # 释放之前锁住的线程，可在其他线程调用

def do_something(thread_id):
    print(td.current_thread())
    print("start thread", thread_id)
    time.sleep(1)
    print("end thread", thread_id)


if __name__ == "__main__":
    for i in range(5):
        t = td.Thread(target=do_something, args=(i,))
        t.start()
        # t.join()  # 等待子线程结束，才执行主线程后面的语句，在for循环使用的话就变成了单线程

多进程

适用于计算密集型任务

基本使用

1
2
3
p = mp.Process(target=Job, args=(a,))
p.start()
p.join()

锁、变量共享

1
2
3
4
5
6
7
8
lock = mp.Lock()
lock.acquire()
lock.release()

# 生成队列，放置值
queue = mp.Queue()
# 各进程共享全局变量
value = mp.Value()

多线程多进程对比（计算密集）

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
import multiprocessing as mp
from concurrent.futures import ThreadPoolExecutor


def calculate_job(ranNum):
    return [i + i**2 + i**3 for i in range(ranNum)]


if __name__ == "__main__":
    """
    完成1000次calculate_job(100) 所花时间
    """

    # exited with code=0 in 12.048 seconds
    for i in range(1000):
        calculate_job(10000)  

    # exited with code=0 in 10.4 seconds
    num_lst = [10000 for i in range(1000)]
    pool = mp.Pool(processes=10)
    pool.map(calculate_job, num_lst)

    # exited with code=0 in 12.391 seconds
    Pool = ThreadPoolExecutor(max_workers=10)
    num_lst = [10000 for i in range(1000)]
    for task in Pool.map(calculate_job, num_lst):
        pass