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Date: Mon, 10 Mar 2008 15:54:47 -0700 (PDT)
From: "Tsz Wo (Nicholas), SZE (JIRA)" <jira@apache.org>
To: core-dev@hadoop.apache.org
Subject: [jira] Updated: (HADOOP-2423) The codes in FSDirectory.mkdirs(...)
 is inefficient.
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     [ https://issues.apache.org/jira/browse/HADOOP-2423?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Tsz Wo (Nicholas), SZE updated HADOOP-2423:
-------------------------------------------

    Attachment: 2423_20080310.patch

1. This is indeed a very good point.  The codes becomes not much simpler.

2. Sure.

3. Since path should not have consective "/", split with limit -1 or 0 are the same.  So, I think the split with less number of parameters is preferred.

4. Because of (1), the changes of addNode(String path, T newNode, boolean inheritPermission) are reverted.  We could make the change from throwing FileNotFoundException to returning null later.

5. Since addChild(...) does not throw FileNotFoundException, nothing to catch now.


> The codes in FSDirectory.mkdirs(...) is inefficient.
> ----------------------------------------------------
>
>                 Key: HADOOP-2423
>                 URL: https://issues.apache.org/jira/browse/HADOOP-2423
>             Project: Hadoop Core
>          Issue Type: Improvement
>          Components: dfs
>    Affects Versions: 0.15.1
>            Reporter: Tsz Wo (Nicholas), SZE
>            Assignee: Tsz Wo (Nicholas), SZE
>         Attachments: 2423_20080130.patch, 2423_20080303.patch, 2423_20080304.patch, 2423_20080304b.patch, 2423_20080304c.patch, 2423_20080304d.patch, 2423_20080310.patch
>
>
> FSDirectory.mkdirs(...) creates List<String> v to store all dirs.  e.g.
> {code}
> //Suppose 
> src = "/foo/bar/bas/"
> //Then,
> v = {"/", "/foo", "/foo/bar", "/foo/bar/bas"}
> {code}
> For each directory string *cur* in v, no matter *cur* already exists or not, it will try to do a unprotectedMkdir(cur, ...).  Then, *cur* is parsed to byte[][] in INodeDirectory.addNode (...).
> We don't need to do the parsing for each string in v.  Instead, byte[][] should be stored.  Also, the loop should not continue once it finds an existing subdirectory.

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