Question

This loop help get some text data from web service:

while True:
    u = urllib2.urlopen('http://url/%d.csv' %inputd)
    f=open('/folder/%s.csv' $inputd,'a')
    csvread = csv.reader(u)
    csvwrite = csv.writer(f)
    csvwrite.writerows(csvread)
    print 'OK','%e'%inputd
    time.sleep(30)

now I try to get different data title in the same time use multiprocessing:

import multiprocessing as mp
import urllib2,csv,random,logging,csv,time

inputd=(abc,def,ghi)

def dataget():
    u = urllib2.urlopen('http://url/%d.csv' %inputd)
    f=open('/folder/%s.csv' $inputd,'a')
    csvread = csv.reader(u)
    csvwrite = csv.writer(f)
    csvwrite.writerows(csvread)
    print 'OK','%e' % inputd
    time.sleep(30)

process=[]
for s in inputd:
    p = mp.Process(target=dataget) 
    ps.append(p)
    p.start()

I hope this can do the getting and saving of “http://url/abc.csv”; “http://url/def.csv”; “http://url/ghi.csv” at the same time, then re-do it again after time.sleep. But it doesn’t work, or do same process in the same time, what logic error did I make?

Answer 1

Your multiprocess implementation will do the url grabbing only once.
If you want that your dataget do the stuff again and again, you missed the While True.

Maybe like this it will work :

import multiprocessing as mp
import urllib2,csv,random,logging,csv,time

inputd=(abc,def,ghi)

def dataget(param):
    while True:
        u = urllib2.urlopen('http://url/%d.csv' %param)
        f=open('/folder/%s.csv' %param,'a')
        csvread = csv.reader(u)
        csvwrite = csv.writer(f)
        csvwrite.writerows(csvread)
        print 'OK','%e'%param
        time.sleep(30)

process=[]
for s in inputd:
    p = mp.Process(target=dataget, args=(s,)) 
    process.append(p)
    p.start()