以下python代码中的多重处理不起作用 [英] Multiprocessing in following python code does not work
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问题描述
我正在尝试通过使用一些多处理来增加我的python程序的执行时间. 假设我有以下示例代码:
I'm trying to increase the execution time of my python program by using some multiprocessing. Suppose I have this sample code:
def foo(q,x,y):
....
q.put(result)
def parallel_funtion(x):
q1 = Queue(); q2 = Queue()
p1 = Process(target=foo,
args=[q1,x,0])
p2 = Process(target=foo,
args=[q2,x,1])
p1.start(); p2.start()
p1.join(); p2.join()
z = max(q1.get(), q2.get())
return z
def function(list)
.....
for i in list:
parallel_function(i)
main():
function(aList)
在功能"中循环的第一次迭代之后,该程序特别冻结在此行中:
After the first iteration in the cycle in "function" the program freezes specifically in this row:
z = max(q1.get(), q2.get())
为什么?
推荐答案
问题在细节上很短,但这对我有用...我修改了您对list
的使用,因为这似乎破坏了python的list
方法(尽管您仍然说过,代码仍会执行):
The question is short on specifics, but this works for me... I modified your use of list
, since that appears to destroy python's list
method (although as you say, the code still executes):
from multiprocessing import Process, Queue
import time
def foo1(queue, procid, arg1, arg2):
# Measure execution time and return the total time in the queue
print "%s got arg1=%s, arg2=%s " % (procid, arg1, arg2)
start = time.time()
ii = arg1
while (ii > 0):
ii = ii - 1
time.sleep(0.01)
# return the output of the call through the Queue
queue.put((time.time() - start)*arg2)
def parallel_function(x):
q1 = Queue()
q2 = Queue()
p1 = Process(target=foo1, args=[q1, 'Proc1', x, 1])
p2 = Process(target=foo1, args=[q2, 'Proc2', x, 2])
p1.start(); p2.start()
p1.join(); p2.join()
# Get return values from each Queue
z = max(q1.get(), q2.get())
return z
def function(_list):
for ii in _list:
print "FUNCTION RESULT input=%s, result=%s" % (ii,
parallel_function(ii))
function([100,120,130,140,150])
输出:
Proc1 got arg1=100, arg2=1
Proc2 got arg1=100, arg2=2
FUNCTION RESULT input=100, result=2.01133012772
Proc1 got arg1=120, arg2=1
Proc2 got arg1=120, arg2=2
FUNCTION RESULT input=120, result=2.4130563736
Proc1 got arg1=130, arg2=1
Proc2 got arg1=130, arg2=2
FUNCTION RESULT input=130, result=2.61448001862
Proc1 got arg1=140, arg2=1
Proc2 got arg1=140, arg2=2
FUNCTION RESULT input=140, result=2.81632232666
Proc1 got arg1=150, arg2=1
Proc2 got arg1=150, arg2=2
FUNCTION RESULT input=150, result=3.01693964005
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