- Process
创建进程的类：Process([group [, target [, name [, args [, kwargs]]]]])，target表示调用对象，args表示调用对象的位置参数元组。kwargs表示调用对象的字典。name为别名。group实质上不使用。
方法：is_alive()、join([timeout])、run()、start()、terminate()。其中，Process以start()启动某个进程。
属性：authkey、daemon（要通过start()设置）、exitcode(进程在运行时为None、如果为–N，表示被信号N结束）、name、pid。其中daemon是父进程终止后自动终止，且自己不能产生新进程，必须在start()之前设置。
例1.1：创建函数并将其作为单个进程
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import multiprocessing
import time
//代码效果参考：https://v.youku.com/v_show/id_XNjQwMDE4NjM3Mg==.html
def worker(interval):
n = 5
while n > 0:
print("The time is {0}".format(time.ctime()))
time.sleep(interval)
n -= 1
if name == "main":
p = multiprocessing.Process(target = worker, args = (3,))
p.start()
print "p.pid:", p.pid
print "p.name:", p.name
print "p.is_alive:", p.is_alive()
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结果
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p.pid: 8736
p.name: Process-1
p.is_alive: True
The time is Tue Apr 21 20:55:12 2015
The time is Tue Apr 21 20:55:15 2015
The time is Tue Apr 21 20:55:18 2015
The time is Tue Apr 21 20:55:21 2015
The time is Tue Apr 21 20:55:24 2015
例1.2：创建函数并将其作为多个进程
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import multiprocessing
import time
def worker_1(interval):
print "worker_1"
time.sleep(interval)
print "end worker_1"
def worker_2(interval):
print "worker_2"
time.sleep(interval)
print "end worker_2"
def worker_3(interval):
print "worker_3"
time.sleep(interval)
print "end worker_3"
if name == "main":
p1 = multiprocessing.Process(target = worker_1, args = (2,))
p2 = multiprocessing.Process(target = worker_2, args = (3,))
p3 = multiprocessing.Process(target = worker_3, args = (4,))
p1.start()
p2.start()
p3.start()
print("The number of CPU is:" + str(multiprocessing.cpu_count()))
for p in multiprocessing.active_children():
print("child p.name:" + p.name + "\tp.id" + str(p.pid))
print "END!!!!!!!!!!!!!!!!!"
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结果
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The number of CPU is:4
child p.name:Process-3 p.id7992
child p.name:Process-2 p.id4204
child p.name:Process-1 p.id6380
END!!!!!!!!!!!!!!!!!
worker_1
worker_3
worker_2
end worker_1
end worker_2
end worker_3
例1.3：将进程定义为类
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import multiprocessing
import time
class ClockProcess(multiprocessing.Process):
def init(self, interval):
multiprocessing.Process.init(self)
self.interval = interval
def run(self):
n = 5
while n > 0:
print("the time is {0}".format(time.ctime()))
time.sleep(self.interval)
n -= 1
//代码效果参考：https://v.youku.com/v_show/id_XNjQwMDE5MjUyOA==.html
if name == 'main':
p = ClockProcess(3)
p.start()
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注：进程p调用start()时，自动调用run()
结果
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the time is Tue Apr 21 20:31:30 2015
the time is Tue Apr 21 20:31:33 2015
the time is Tue Apr 21 20:31:36 2015
the time is Tue Apr 21 20:31:39 2015
the time is Tue Apr 21 20:31:42 2015
例1.4：daemon程序对比结果
1.4-1 不加daemon属性
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import multiprocessing
import time
def worker(interval):
print("work start:{0}".format(time.ctime()));
time.sleep(interval)
print("work end:{0}".format(time.ctime()));
if name == "main":
p = multiprocessing.Process(target = worker, args = (3,))
p.start()
print "end!"
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结果
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end!
work start:Tue Apr 21 21:29:10 2015
work end:Tue Apr 21 21:29:13 2015
1.4-2 加上daemon属性
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import multiprocessing
import time
def worker(interval):
print("work start:{0}".format(time.ctime()));
time.sleep(interval)
print("work end:{0}".format(time.ctime()));
if name == "main":
p = multiprocessing.Process(target = worker, args = (3,))
p.daemon = True
p.start()
print "end!"
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结果
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end!
