[jira] [Created] (HADOOP-12474) Fix data race when allocating server port in MiniKMS

["Mingliang Liu (JIRA)" <ji...@apache.org>]

Mingliang Liu created HADOOP-12474:
--------------------------------------

             Summary: Fix data race when allocating server port in MiniKMS 
                 Key: HADOOP-12474
                 URL: https://issues.apache.org/jira/browse/HADOOP-12474
             Project: Hadoop Common
          Issue Type: Bug
            Reporter: Mingliang Liu
            Assignee: Mingliang Liu


In {{MiniKMS}}, there is potential data race when create jetty server in {{createJettyServer}}. It looks like the code searches for a free port and then starts jetty, but maybe there's enough of a race condition between port location and jetty.start to cause intermittent failures.
{code}
      ServerSocket ss = new ServerSocket((inPort < 0) ? 0 : inPort, 50, localhost);
      int port = ss.getLocalPort();
      Server server = new Server(0);
      if (!ssl) {
        server.getConnectors()[0].setHost(host);
        server.getConnectors()[0].setPort(port);
      } else {
        ...
        c.setPort(port);
{code}

We've seen test failures saying {{java.net.BindException: Address already in use}}, e.g. [https://builds.apache.org/job/PreCommit-HDFS-Build/12942/testReport/]

As in [HADOOP-12417], we should always bind port 0 which gives us an ephemeral port, instead of searching a free port before starting jetty.



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