异步dns查找,但结果指向同一文件

我必须做大量的dns naptr查找(每分钟数千次)。 我使用dnspython运行一个python脚本,读取一个文件并写回另一个文件。请求速率约为每秒300个请求。 我尝试在python中使用异步dns aiodns ,但数字是一样的。 可能我的剧本有缺陷。请看下面。这是Python3.4。

但是如果结果必须返回到一个文件,那么甚至可以异步查找吗?

import asyncio
import aiodns

...

loop = asyncio.get_event_loop()
resolver = aiodns.DNSResolver(loop=loop)
resolver.nameservers = ['x.y.w.z']

...

@asyncio.coroutine
def getsip(number):

    try:
        strQuery = str(dns.e164.from_e164("+" + number))
        answer = yield from resolver.query(strQuery, 'NAPTR')

        for rdata in answer:
            return rdata.regex

    except:
        return ""

with open(filename, 'r') as fread, open(filenameOut, 'w') as fwrite:
    reader = csv.DictReader(fread, delimiter='|', quoting=csv.QUOTE_NONE)
    reader.fieldnames = fieldnamesIn

    writer = csv.DictWriter(fwrite, fieldnames = fieldnamesOut, delimiter='|')

    for row in reader:
        sys.stdout.write("Processing record number: %d \r" % (total) )
        sys.stdout.flush()
        total+=1
        answer = loop.run_until_complete(getsip(row['NUM']))
        if answer == "":
            missingAnswers+=1

        writer.writerow({'NUM': row['NUM'], 'SIP': answer})

print("Records not found: " + str(missingAnswers) + " of total " +  str(total) + " records.")