Elaborating error message when incorrect port number is specified in impala-shell.
Elaborating error message when incorrect port number is specified in impala-shell.

I recently helped debug an issue where impala-shell was being given
the hiveserver2 port rather than the beeswax port. I've updated
the error message a little bit to indicate that this may be the issue.
Here is the new message:

  $impala-shell.sh -i ....:21050 -q 'select 1'
  Starting Impala Shell without Kerberos authentication
  Error: Unable to communicate with impalad service. This service may
  not be an impalad instance. A common problem is that the port
  specified does not match the -beeswax_port flag on the underlying
  impalad. Check host:port and try again.
  Traceback (most recent call last):
    File "/home/philip/src/Impala/shell/impala_shell.py", line 1709, in <module>
      execute_queries_non_interactive_mode(options, query_options)
    File "/home/philip/src/Impala/shell/impala_shell.py", line 1565, in execute_queries_non_interactive_mode
      shell = ImpalaShell(options, query_options)
    File "/home/philip/src/Impala/shell/impala_shell.py", line 232, in __init__
      self.do_connect(options.impalad)
    File "/home/philip/src/Impala/shell/impala_shell.py", line 798, in do_connect
      self._connect()
    File "/home/philip/src/Impala/shell/impala_shell.py", line 842, in _connect
      result = self.imp_client.connect()
    File "/home/philip/src/Impala/shell/impala_client.py", line 257, in connect
      result = self.ping_impala_service()
    File "/home/philip/src/Impala/shell/impala_client.py", line 262, in ping_impala_service
      return self.imp_service.PingImpalaService()
    File "/home/philip/src/Impala/shell/gen-py/ImpalaService/ImpalaService.py", line 229, in PingImpalaService
      return self.recv_PingImpalaService()
    File "/home/philip/src/Impala/shell/gen-py/ImpalaService/ImpalaService.py", line 245, in recv_PingImpalaService
      raise x
  thrift.Thrift.TApplicationException: Invalid method name: 'PingImpalaService'

Change-Id: I14465e8f666c4a5f3968db8864dfdb1205641a33
Reviewed-on: http://gerrit.cloudera.org:8080/11368
Reviewed-by: Impala Public Jenkins <039b6b20426ff68ebe492b3021890d8c8fd010c9@cloudera.com>
Tested-by: Impala Public Jenkins <039b6b20426ff68ebe492b3021890d8c8fd010c9@cloudera.com>

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