升级python3.7后无法连接kafka问题

python从3.6升级到3.7后，kafka出现无法连接的问题，具体问题如下：

kafka-python==1.4.7以下：

Traceback (most recent call last):
  File "/home/yujialiang/PycharmProjects/kafka-learn/sender.py", line 1, in <module>
    from kafka import KafkaProducer
  File "/home/yujialiang/anaconda3/lib/python3.7/site-packages/kafka/__init__.py", line 23, in <module>
    from kafka.producer import KafkaProducer
  File "/home/yujialiang/anaconda3/lib/python3.7/site-packages/kafka/producer/__init__.py", line 4, in <module>
    from kafka.producer.simple import SimpleProducer
  File "/home/yujialiang/anaconda3/lib/python3.7/site-packages/kafka/producer/simple.py", line 54
    return '<SimpleProducer batch=%s>' % self.async
                                                  ^
SyntaxError: invalid syntax

错误原因：

kafka-python1.4.7以下版本中.async关键词和python3.7以后版本冲突，python3.7重新定义了.async关键词，故导致不能用

kafka-python==1.4.7及以上版本：

Traceback (most recent call last):
  File "/home/yujialiang/anaconda3/lib/python3.7/site-packages/kafka/producer/sender.py", line 60, in run
    self.run_once()
  File "/home/yujialiang/anaconda3/lib/python3.7/site-packages/kafka/producer/sender.py", line 160, in run_once
    self._client.poll(timeout_ms=poll_timeout_ms)
  File "/home/yujialiang/anaconda3/lib/python3.7/site-packages/kafka/client_async.py", line 578, in poll
    self._maybe_connect(node_id)
  File "/home/yujialiang/anaconda3/lib/python3.7/site-packages/kafka/client_async.py", line 388, in _maybe_connect
    conn.connect()
  File "/home/yujialiang/anaconda3/lib/python3.7/site-packages/kafka/conn.py", line 422, in connect
    if self._try_handshake():
  File "/home/yujialiang/anaconda3/lib/python3.7/site-packages/kafka/conn.py", line 501, in _try_handshake
    self._sock.do_handshake()
  File "/home/yujialiang/anaconda3/lib/python3.7/ssl.py", line 1108, in do_handshake
    self._sslobj.do_handshake()
ssl.SSLError: [SSL: UNKNOWN_STATE] unknown state (_ssl.c:1045)
ERROR:kafka.producer.sender:Uncaught error in kafka producer I/O thread

或者在接收数据时发生如下错误：

ssl.SSLCertVerificationError: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: IP address mismatch, certificate is not valid for '100.95.146.129'. (_ssl.c:1045)

原因：

1.版本问题导致，服务端版本合客户端版本不一致，如服务端版本kafka_2.11-0.9.0.1，客户端使用kafka自带 shell，版本 kafka_2.11-0.10.0，改为kafka_2.11-0.9.0.1 版本即可解决问题。

2.如果使用的是安全kafka（dms或者经过ssl认证），在python3.7及以上版本对匹配服务端ip地址的校验及cn认证，解决办法在初始化kafkaProducer或kafkaConsumer中设置ssl_check_hostname=False即可