[jira] [Created] (IMPALA-7800) Reject or timeout new incoming connections once --fe_service_threads limit is reached

["Michael Ho (JIRA)" <ji...@apache.org>]

Michael Ho created IMPALA-7800:
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             Summary: Reject or timeout new incoming connections once --fe_service_threads limit is reached
                 Key: IMPALA-7800
                 URL: https://issues.apache.org/jira/browse/IMPALA-7800
             Project: IMPALA
          Issue Type: Improvement
          Components: Clients
    Affects Versions: Impala 2.12.0, Impala 3.0
            Reporter: Michael Ho


Currently, the number of frontend service threads is controlled by {{--fe_service_threads}}. Once this limit is reached, the worker threads of {{connection_setup_pool}} will block until some of the service threads exit. New incoming connections will be buffered in a queue in {{connection_setup_pool}} until it fills up. Currently, there is no time out for all these buffered connections in the queue. Consequently, if the number of frontend service threads max'ed out for an extended period of time, a client trying to connect to Impala will feel "stuck" until a front end service thread is available.

We should consider either rejecting any new connections once {{--fe_service_threads}} limit is reached or imposing a tunable upper bound on the wait time for connections in the queue to improve the users' experience. cc'ing [~zoram]



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