multiprocessing的用法與threading的用法十分相似
from multiprocessing import Process
def f():
print('multiprocessing')
p = Process(target=f,args=())
p.start()
p.join()
在兩個進程中交換對象
使用隊列
from multiprocessing import Process,Queue,Pipe
def use_queue(q):
q.put([42,'hello'])
q = Queue()
p = Process(target=use_queue,args=(q,))
p.start()
print(q.get())
p.join()
[42, 'hello']
使用Pipe
def use_pipe(conn):
conn.send([42,'hello'])
conn.close()
parent_conn,child_conn = Pipe()
p_p = Process(target=use_pipe,args=(child_conn,))
p_p.start()
print(parent_conn.recv())
p_p.join()
[42, 'hello']
兩個進程異步執(zhí)行
from multiprocessing import Process,Lock
def syn_f(l,num):
l.acquire()
print('hello synchronization',num)
l.release()
lock = Lock()
for num in range(10):
p_s = Process(target=syn_f,args=(lock,num)).start()
('hello synchronization', 0)
('hello synchronization', 1)
('hello synchronization', 2)
('hello synchronization', 3)
('hello synchronization', 4)
('hello synchronization', 6)
('hello synchronization', 5)
('hello synchronization', 7)
('hello synchronization', 8)
('hello synchronization', 9)
使用進程池
from multiprocessing import Pool
def f(x):
return x*x
po = Pool(5)
result = po.apply_async(f,[10])
result.get(timeout=1)
# 使用map函數(shù)來迭代應(yīng)用
print(po.map(f,range(10)))
?
[0, 1, 4, 9, 16, 25, 36, 49, 64, 81]
在兩個進程之間分享狀態(tài)
from multiprocessing import Process,Array,Value
def share_state(n,a):
n.value = 1234
for i in range(len(a)):
a[i] = -a[i]
num = Value('d',1) # d表示雙精度整數(shù)
arr = Array('i',range(10)) # i表示無符號整數(shù)
p = Process(target=share_state,args=(num,arr))
p.start()
p.join()
?
print(num.value)
print(arr[:])
?
1234.0
[0, -1, -2, -3, -4, -5, -6, -7, -8, -9]
使用manager對象管理共享
from multiprocessing import Process,Manager
def use_manager(d,l):
d[1] = 1
d['o'] = 'o'
l.reverse()
manager = Manager()
d = manager.dict()
l = manager.list(range(10))
p = Process(target=use_manager,args=(d,l))
p.start()
p.join()
?
print(d)
print(l)
{1: 1, 'o': 'o'}
[9, 8, 7, 6, 5, 4, 3, 2, 1, 0]
