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The proposed change is backward compatible.

Rejected Alternatives

1. Use connections.max.idle.ms to instead of connect.timeout.ms

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1. :  it will close idle connections after the number of milliseconds specified by this config, default is 9 minutes
   But this parameter is only work for the connection phase, if the channel is connecting, this parameter can not close the channel.
   
   
2. Enhanced request.timeout.ms to support the connecting timeout:  we are using request.timeout.ms to control not only for the request(produce request or fetch request), but also for the connecting phase.
   If we only use the request.timeout for the connect and process request,  it is not flexible for some case：  for example we need the connecting phase to a short time(5s), and the request for a longer time(40s).