实例变量在更新多个进程后保持不变

Question

对于下面的代码，我希望dr.hello的输出是10，因为10个派生进程调用updateHello一次，以增加dr.hello。但现在是0，原因是什么？我该如何改变它？你知道吗

from multiprocessing import Process, Lock

class myWorker:
    def __init__(self, lock, driver, i):
        self.idx=i
        self.driver=driver
        self.lock=lock

    def run(self):
        self.driver.updateHello(self.lock,self.idx)

class driver:
    hello=0
    def __init__(self):
        self.lock=Lock()

    def workerrun(self,lock, i):
        worker1=myWorker(lock,self,i)
        worker1.run()

    def run(self):
        D=[Process(target=self.workerrun,args=(self.lock,i)) for i in range(10)]
        for d in D:
            d.start()
        for d in D:
            d.join()

    def updateHello(self,l,i):
        l.acquire()
        self.hello+=1
        print "update from",i
        l.release()

if __name__=='__main__':
    dr=driver()
    dr.run()
    print dr.hello

Answer 1

现在可以了，我通过将Padraic解决方案从类变量更改为实例变量来实现

from multiprocessing import Process, Lock, Value

class myWorker:
    def __init__(self, lock, driver, i):
        self.idx=i
        self.driver=driver
        self.lock=lock

    def run(self):
        self.driver.updateHello(self.lock,self.idx)

class driver(object):
    #hello = Value("i",lock=True) # create shared variable of type int
    #hello.value = 0

    def __init__(self):
        self.lock=Lock()
        self.hello=Value("i",0)

    def workerrun(self,lock, i):
        worker1=myWorker(lock,self,i)
        worker1.run()

    def run(self):
        D=[Process(target=self.workerrun,args=(self.lock,i)) for i in range(10)]
        for d in D:
            d.start()
        for d in D:
            d.join()

    def updateHello(self,l,i):
        with self.lock: # acquire lock
            self.hello.value += 1
            print ("update from", i)
        # release lock

if __name__=='__main__':
    dr=driver()
    dr.run()
    print(dr.hello.value)

Answer 2

我认为共享变量需要一个multiprocessing.Value

from multiprocessing import Process, Lock, Value

class myWorker:
    def __init__(self, lock, driver, i):
        self.idx=i
        self.driver=driver
        self.lock=lock

    def run(self):
        self.driver.updateHello(self.lock,self.idx)

class driver:
    hello = Value("i",lock=True) # create shared variable of type int
    hello.value = 0

    def __init__(self):
        self.lock=Lock()

    def workerrun(self,lock, i):
        worker1=myWorker(lock,self,i)
        worker1.run()

    def run(self):
        D=[Process(target=self.workerrun,args=(self.lock,i)) for i in range(10)]
        for d in D:
            d.start()
        for d in D:
            d.join()

    def updateHello(self,l,i):
        with self.lock: # acquire lock
            driver.hello.value += 1
            print ("update from", i)
        # release lock

if __name__=='__main__':
    dr=driver()
    dr.run()
    print(driver.hello.value)

Ipython输出：

if __name__=='__main__':
    dr=driver()
    dr.run()
    print(driver.hello.value)

##   End pasted text  
('update from', 0)
('update from', 1)
('update from', 2)
('update from', 5)
('update from', 6)
('update from', 7)
('update from', 4)
('update from', 3)
('update from', 8)
('update from', 9)
10