python 多进程 (并行编程 11)

import multiprocessing

def foo(i):
print('called function in process %s' % i)
if name=="main":
pros=[]
for i in range(5):
p=multiprocessing.Process(target=foo,args=(i,))
pros.append(p)
p.start()
p.join()

线程和进程性能

import multiprocessing
import datetime
import threading
def foo(i):
print('called function in process %s' % i)
if name=="main":
pros=[]
starttime = datetime.datetime.now()
for i in range(5):
p=multiprocessing.Process(target=foo,args=(i,))
pros.append(p)
p.start()
p.join()
endtime = datetime.datetime.now()
print((endtime - starttime).microseconds/1000)
starttime = datetime.datetime.now()
for i in range(5):
p = threading.Thread(target=foo, args=(i,))
pros.append(p)
p.start()
p.join()
endtime = datetime.datetime.now()
print((endtime - starttime).microseconds / 1000)

called function in process 0
called function in process 1
called function in process 2
called function in process 3
called function in process 4
99.059
called function in process 0
called function in process 1
called function in process 2
called function in process 3
called function in process 4
0.998

获取CPU数量：multiprocessing.cpu_count()

import multiprocessing
import time

def process(num):
time.sleep(num)
print('Process:', num)

if name == 'main':
for i in range(5):
p = multiprocessing.Process(target=process, args=(i,))
p.start()

print('CPU number:' + str(multiprocessing.cpu_count()))
for p in multiprocessing.active_children():
    print('Child process name: ' + p.name + ' id: ' + str(p.pid))

print('Process Ended')

继承Process

from multiprocessing import Process
import time

class MyProcess(Process):
def init(self, loop):
Process.init(self)
self.loop = loop

def run(self):
    for count in range(self.loop):
        time.sleep(1)
        print('Pid: ' + str(self.pid) + ' LoopCount: ' + str(count))

if name == 'main':
for i in range(2, 5):
p = MyProcess(i)
p.start()

daemon=True 守护进程在主进程结束马上终止，如果daemon=False ，主进程结束也不会结束

from multiprocessing import Process
import time
import os

def func(num):
print(f'{num},pid:{os.getpid()},ppid:{os.getppid()}')
while True:
print('is alive')
time.sleep(0.5)

def wahaha():
i = 0
while i < 5:
i += 1
print(f'第{i}秒')
time.sleep(1)

if name == 'main':
Process(target=wahaha).start() #子进程在主进程结束后仍然正常执行
p = Process(target=func,args=(1,))
p.daemon = True #主进程结束,该守护进程结束
p.start()
time.sleep(3)
print(f'pid:{os.getpid()},ppid:{os.getppid()}')
print('主进程结束')

p.terminate() 进程终止