Прервите первый цикл как 3 процесса,
def func(start, final):
for x in xrange(start, final):
for y in xrange(0,3000):
for z in xrange(0,700):
operationg_tag = "%s-%s-%s" % (x,y,z)
operation_code = ....
def main():
total = 14000
div_total = int(14000 / 3)
rest_div_total = 14000%3
t1 = multiprocessing.Process(target = func,name = "", args=(100, div_total)
t2 = multiprocessing.Process(target = func,name = "", args=(div_total, div_total*2)
t3 = multiprocessing.Process(target = func,name = "", args=(div_total*2, div_total*3 + rest_div_total + 1)
list_threads = [t1,t2,t3]
for i in list_threads:
i.start()
for i in list_threads:
i.join()
if __name__ == "__main__":
main()
Вы можете создать больше процессов, если хотите, но 3 Это хорошо.