[jira] [Commented] (HADOOP-11387) Simplify NetUtils#canonicalizeHost()

["Haohui Mai (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HADOOP-11387?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14361394#comment-14361394 ] 

Haohui Mai commented on HADOOP-11387:
-------------------------------------

[~jeagles] do you have any more comments? I plan to commit it next Monday if there is no objection.

> Simplify NetUtils#canonicalizeHost()
> ------------------------------------
>
>                 Key: HADOOP-11387
>                 URL: https://issues.apache.org/jira/browse/HADOOP-11387
>             Project: Hadoop Common
>          Issue Type: Bug
>            Reporter: Haohui Mai
>            Assignee: Li Lu
>         Attachments: HADOOP-11387-121514-1.patch, HADOOP-11387-121514-2.patch, HADOOP-11387-121514.patch
>
>
> Currently {{NetUtils#canonicalizeHost}} uses a {{ConcurrentHashMap}} to cache the canonicalized hostname.
> {code}
>   private static String canonicalizeHost(String host) {
>     // check if the host has already been canonicalized
>     String fqHost = canonicalizedHostCache.get(host);
>     if (fqHost == null) {
>       try {
>         fqHost = SecurityUtil.getByName(host).getHostName();
>         // slight race condition, but won't hurt
>         canonicalizedHostCache.put(host, fqHost);
>       } catch (UnknownHostException e) {
>         fqHost = host;
>       }
>     }
>     return fqHost;
>   }
> {code}
> The code triggers a findbugs warning. The cache is used for caching NN resolution for the client-side {{FileSystem}} objects. In most of the use cases there are at most one or two instances in the cache. This jira proposes to eliminate the findbugs warnings and to simplify the code using {{CacheMap}}.



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