[jira] [Created] (KUDU-2508) nscd should be recommended even when /etc/hosts is used for name resolution

["Adar Dembo (JIRA)" <ji...@apache.org>]

Adar Dembo created KUDU-2508:
--------------------------------

             Summary: nscd should be recommended even when /etc/hosts is used for name resolution
                 Key: KUDU-2508
                 URL: https://issues.apache.org/jira/browse/KUDU-2508
             Project: Kudu
          Issue Type: Bug
          Components: documentation
    Affects Versions: n/a
            Reporter: Adar Dembo


It's been observed in several clusters in the wild that on old platforms like el6, name resolution can be slow even when /etc/hosts is used. That's because opening /etc/hosts requires the creation of an mmap, which means the kernel has to take mmap_sem for writing, and that can contend with all sorts of other system activity. Furthermore, glibc synchronizes all resolution on a single lock, so there's opportunity for contention there. See [this mailing list post|http://mail-archives.apache.org/mod_mbox/kudu-user/201711.mbox/%3CCADY20s4ePet5gHnqz7HZ13CoY-1SvUNnNOZ8dXrN+YXrLx5TTg@mail.gmail.com%3E] for more details.

We should document that for better scalability on nodes hosting many replicas, it's best to use nscd to cache this kind of name resolution too.



--
This message was sent by Atlassian JIRA
(v7.6.3#76005)