我不知道为什么，但是这段代码有时有效，有时会抛出错误的提示？ ：

Question

我有这段代码可以将多个消息发布到不同的主题。

""" 
Publish some messages to queue
"""
import paho.mqtt.publish as publish

host ="test.mosquitto.org"

msgs = [{'topic': "A/A1", 'payload': "30"},
        {'topic': "A/A2", 'payload': "40"},
        {'topic': "A/A3", 'payload': "1"}]


if __name__ == '__main__':

    # publish multiple messages
    publish.multiple(msgs, hostname=host)

但有时它对我有用并发布数据，有时会引发此错误。

Traceback (most recent call last):
  File "/home/pi/Desktop/NRF24L01/publish.py", line 22, in <module>
    publish.multiple(msgs, hostname=host)
  File "/usr/local/lib/python3.5/dist-packages/paho/mqtt/publish.py", line 159, in multiple
    client.connect(hostname, port, keepalive)
  File "/usr/local/lib/python3.5/dist-packages/paho/mqtt/client.py", line 839, in connect
    return self.reconnect()
  File "/usr/local/lib/python3.5/dist-packages/paho/mqtt/client.py", line 962, in reconnect
    sock = socket.create_connection((self._host, self._port), source_address=(self._bind_address, 0))
  File "/usr/lib/python3.5/socket.py", line 693, in create_connection
    for res in getaddrinfo(host, port, 0, SOCK_STREAM):
  File "/usr/lib/python3.5/socket.py", line 732, in getaddrinfo
    for res in _socket.getaddrinfo(host, port, family, type, proto, flags):
socket.gaierror: [Errno -3] **Temporary failure in name resolution**

经过大量研究，我看到一些评论说这是DNS问题或代理已关闭，但无论如何都无法解决。请谁能帮助我？ 预先感谢。

Answer 1

错误的重要部分在这里：

import urlparse
import scrapy

from scrapy.http import Request

class pwc_tax(scrapy.Spider):
    name = "sec_gov"

    allowed_domains = ["www.sec.gov"]
    start_urls = ["https://secsearch.sec.gov/search?utf8=%3F&affiliate=secsearch&query=exhibit+10"]

    def parse(self, response):
        for href in response.css('div#all_results h3 a::attr(href)').extract():
            yield Request(
                url=response.urljoin(href),
                callback=self.parse_article
            )

    def parse_article(self, response):
        for href in response.css('div.download_wrapper a[href$=".pdf"]::attr(href)').extract():
            yield Request(
                url=response.urljoin(href),
                callback=self.save_pdf
            )

    def save_pdf(self, response):
        path = response.url.split('/')[-1]
        self.logger.info('Saving PDF %s', path)
        with open(path, 'wb') as f:
            f.write(response.body)

这意味着您在其中运行代码的Raspberry Pi找不到socket.gaierror: [Errno -3] **Temporary failure in name resolution** 的IP地址。

这很可能意味着您的代码没有错，但是您需要查看Raspberry Pi如何连接到互联网。

可能有许多问题，但其中一些可能是

• WiFi连接弱
• 宽带连接错误
• 您的ISP遇到的问题

不幸的是，我们几乎无法通过任何方式远程了解它。