Error after 6th iteration, ran out of RAM

error.txt

OSError: [Errno 12] Cannot allocate memory

social_stats.py

import math
import psycopg2
from socialanalytics import pinterest
from socialanalytics import facebook
from socialanalytics import twitter
from socialanalytics import google_plus
from time import strftime, sleep
import multiprocessing as mp

NUM_PROCESSES = 10
NUM_URLS = 1000

print "Number of Processes:", NUM_PROCESSES

conn = psycopg2.connect("dbname='***' user='***' host='***' password='***'")
cur = conn.cursor()

def getSocialStats(url):
    now = strftime("%Y-%m-%d %H:%M:%S")
    p = pinterest.getPins(url[1])
    f = facebook.getObject(url[1])
    t = twitter.getShares(url[1])
    g = google_plus.getPlusOnes(url[1])
    return [url[0], url[1], now, p['pin_count'], f['like_count'], f['share_count'], f['comment_count'], t['share_count'], g['plus_count']]

# Get Count of urls
cur.execute("SELECT COUNT(*) FROM urls;")
COUNT_URLS = float(cur.fetchone()[0])

SELECT_CYCLES = math.ceil(COUNT_URLS / NUM_URLS)

for i in range(int(SELECT_CYCLES)):
    offset = i * NUM_URLS

    # Select urls
    cur.execute("SELECT id, url FROM urls LIMIT " + str(NUM_URLS) + " OFFSET " + str(offset) + ";")
    urls = cur.fetchall()

    url_chunks = []
    temp = []

    # Parse URLs into chunks
    while len(urls) > 0:
        temp.append(urls.pop())
        if len(temp) == NUM_PROCESSES:
            url_chunks.append(temp)
            temp = []
    # Add any remaining urls
    if len(temp) > 0:
        url_chunks.append(temp)

    p = mp.Pool(NUM_PROCESSES)

    res = []

    print "Starting Fetching", strftime("%Y-%m-%d %H:%M:%S")

    for url_chunk in url_chunks:
        res += p.map(getSocialStats, url_chunk)

    for r in res:
        try:
            cur.execute("INSERT INTO social_stats_staging (url_id, fetched_at, pinterest_pins, facebook_likes, facebook_shares, facebook_comments, twitter_shares, google_plus_ones) VALUES(%s, %s, %s, %s, %s, %s, %s, %s);", (r[0], r[2], r[3], r[4], r[5], r[6], r[7], r[8]))
            conn.commit()
        except:
            conn.rollback()
            print "Error saving to DB"