Python 如何从多进程中收集结果?
我的python代码有问题。我想要的是每个进程都写在一个字典中。我得到的是每个进程都会写入自己的字典 为了说明这一点: 运行代码后:我得到以下输出:Python 如何从多进程中收集结果?,python,multiprocessing,Python,Multiprocessing,我的python代码有问题。我想要的是每个进程都写在一个字典中。我得到的是每个进程都会写入自己的字典 为了说明这一点: 运行代码后:我得到以下输出: P 0: {0: 1} P 2: {2: 1} P 4: {4: 1} P 6: {6: 1} P 8: {8: 1} All: {} 我想要的是: P 0: {0: 1} P 2: {2: 1} P 4: {4: 1} P 6: {6: 1} P 8: {8: 1} All: {0: 1, 2: 1, 4: 1, 6: 1, 8: 1} 以下
P 0: {0: 1}
P 2: {2: 1}
P 4: {4: 1}
P 6: {6: 1}
P 8: {8: 1}
All: {}
我想要的是:
P 0: {0: 1}
P 2: {2: 1}
P 4: {4: 1}
P 6: {6: 1}
P 8: {8: 1}
All: {0: 1, 2: 1, 4: 1, 6: 1, 8: 1}
以下是我的示例代码:
from multiprocessing import Process, Lock, cpu_count
class multiprocessingExample():
global d
d = {}
global lock
lock = Lock()
def __init__(self):
pass
def proc(self, num):
global lock
global d
with lock:
if(num in d):
d[num] = d[num] + 1
else:
d[num] = 1
print("P " + str(num) + ": " + str(d))
def main(self):
jobs = []
for i in range(0, 10):
if(i%2 == 0):
p = Process(target=self.proc, args=(i,))
jobs.append(p)
for job in jobs:
job.start()
for job in jobs:
job.join()
print("All: " + str(d))
obj = multiprocessingExample()
obj.main()
如果您能告诉我出了什么问题,那就太好了。您似乎没有正确地使用
global
。它用于确保每当您提到变量时,您指的是全局范围内的变量:
#global scope
count = 0
def fun():
#local variables
local_count = 0
# 'when I say "do something to `count`",
# I mean the global variable'
global count
count += 1
您需要首先声明这些变量,如下所示:
from multiprocessing import Process, Lock, cpu_count
# initialize global variables
d = {}
lock = Lock()
class multiprocessingExample():
global d
# here you're overwriting them, so previous
# values are no longer available.
# you probably shouldn't do this, better initialize them
# in global namespace
#d = {}
global lock
请注意,您还可以执行global d、lock等操作,因此您不必每次都编写global
。不要使用global,使用a:
这将输出如下内容:
P 0: {0: 1}
P 2: {0: 1, 2: 1}
P 4: {0: 1, 2: 1, 4: 1}
P 8: {0: 1, 8: 1, 2: 1, 4: 1}
P 6: {0: 1, 8: 1, 2: 1, 4: 1, 6: 1}
All: {0: 1, 8: 1, 2: 1, 4: 1, 6: 1}
“不要使用全局”本身就是一个很好的答案。感谢您将我介绍给Manager
@msw,不用担心,这里有一个Manager.dict,您有嵌套的dict,在这种情况下,您需要合并一个Manager.list
P 0: {0: 1}
P 2: {0: 1, 2: 1}
P 4: {0: 1, 2: 1, 4: 1}
P 8: {0: 1, 8: 1, 2: 1, 4: 1}
P 6: {0: 1, 8: 1, 2: 1, 4: 1, 6: 1}
All: {0: 1, 8: 1, 2: 1, 4: 1, 6: 1}