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From "Ivan A. Veselovsky (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HADOOP-8849) FileUtil#fullyDelete should grant the target directories +rwx permissions before trying to delete them
Date Fri, 05 Oct 2012 14:06:07 GMT

     [ https://issues.apache.org/jira/browse/HADOOP-8849?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Ivan A. Veselovsky updated HADOOP-8849:
---------------------------------------

    Attachment: HADOOP-8849-vs-trunk-2.patch

version #2 of the patch where the findbugs warning is worked around.
                
> FileUtil#fullyDelete should grant the target directories +rwx permissions before trying
to delete them
> ------------------------------------------------------------------------------------------------------
>
>                 Key: HADOOP-8849
>                 URL: https://issues.apache.org/jira/browse/HADOOP-8849
>             Project: Hadoop Common
>          Issue Type: Improvement
>            Reporter: Ivan A. Veselovsky
>            Assignee: Ivan A. Veselovsky
>            Priority: Minor
>         Attachments: HADOOP-8849-vs-trunk-2.patch
>
>
> 2 improvements are suggested for implementation of methods org.apache.hadoop.fs.FileUtil.fullyDelete(File)
and org.apache.hadoop.fs.FileUtil.fullyDeleteContents(File):
>  
> 1) We should grant +rwx permissions the target directories before trying to delete them.
> The mentioned methods fail to delete directories that don't have read or execute permissions.
> Actual problem appears if an hdfs-related test is timed out (with a short timeout like
tens of seconds), and the forked test process is killed, some directories are left on disk
that are not readable and/or executable. This prevents next tests from being executed properly
because these directories cannot be deleted with FileUtil#fullyDelete(), so many subsequent
tests fail. So, its recommended to grant the read, write, and execute permissions the directories
whose content is to be deleted.
> 2) Generic reliability improvement: we shouldn't rely upon File#delete() return value,
use File#exists() instead. 
> FileUtil#fullyDelete() uses return value of method java.io.File#delete(), but this is
not reliable because File#delete() returns true only if the file was deleted as a result of
the #delete() method invocation. E.g. in the following code
> if (f.exists()) { // 1
>   return f.delete(); // 2
> }
> if the file f was deleted by another thread or process between calls "1" and "2", this
fragment will return "false", while the file f does not exist upon the method return.
> So, better to write
> if (f.exists()) {
>   f.delete();
>   return !f.exists();
> }

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