[HDFS-9519] Some coding improvement in SecondaryNameNode#main

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 2.8.0, 3.0.0-alpha1
• Component/s: namenode
• Hadoop Flags: Reviewed
• Assignee: Xiao Chen
• Reporter: Yongjun Zhang
• Created: 07/Dec/15 23:52
• Updated: 30/Aug/16 01:22
• Resolved: 12/Dec/15 05:31

Description

Two nits:

1. The checking whether secondary is null is not necessary in the following code in SecondaryNameNode.java.
2. The comment in this code seems to imply that "when secondary is not null, SNN was stared as a daemon.", and this is not true. Suggest to improve the comment to make it clear,

Assign to Xiao since he worked on HDFS-3059. Thanks Xiao.

      if (secondary != null) {
        // The web server is only needed when starting SNN as a daemon,
        // and not needed if called from shell command. Starting the web server
        // from shell may fail when getting credentials, if the environment
        // is not set up for it, which is most of the case.
        secondary.startInfoServer();

        secondary.startCheckpointThread();
        secondary.join();
      }

Issue Links

• relates to: HDFS-3059 ssl-server.xml causes NullPointer