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https://issues.apache.org/jira/browse/HADOOP-15893?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16702927#comment-16702927
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sunlisheng commented on HADOOP-15893:
-------------------------------------
I add a patch.
> fs.TrashPolicyDefault: can't create trash directory and race condition
> ----------------------------------------------------------------------
>
> Key: HADOOP-15893
> URL: https://issues.apache.org/jira/browse/HADOOP-15893
> Project: Hadoop Common
> Issue Type: Bug
> Components: common
> Reporter: sunlisheng
> Priority: Major
> Attachments: HADOOP-15893.001.patch, HADOOP-15893.002.patch
>
>
> there is race condition in method moveToTrash class TrashPolicyDefault
> try {
> if (!fs.mkdirs(baseTrashPath, PERMISSION))
> { // create current LOG.warn("Can't create(mkdir) trash directory: " +
> baseTrashPath); return false; }
> } catch (FileAlreadyExistsException e) {
> // find the path which is not a directory, and modify baseTrashPath
> // & trashPath, then mkdirs
> Path existsFilePath = baseTrashPath;
> while (!fs.exists(existsFilePath))
> { existsFilePath = existsFilePath.getParent(); }
> {color:#FF0000}// case{color}
> {color:#FF0000} other thread deletes existsFilePath here ，the results
> doesn't meet expectation{color}
> {color:#FF0000} for example{color}
> {color:#FF0000} there is
> /user/u_sunlisheng/.Trash/Current/user/u_sunlisheng/b{color}
> {color:#FF0000} when delete /user/u_sunlisheng/b/a. if existsFilePath is
> deleted, the result is
> /user/u_sunlisheng/.Trash/Current/user/u_sunlisheng+timstamp/b/a{color}
> {color:#FF0000} so when existsFilePath is deleted, don't modify
> baseTrashPath. {color}
> baseTrashPath = new Path(baseTrashPath.toString().replace(
> existsFilePath.toString(), existsFilePath.toString() + Time.now())
> );
> trashPath = new Path(baseTrashPath, trashPath.getName());
> // retry, ignore current failure
> --i;
> continue;
> } catch (IOException e)
> { LOG.warn("Can't create trash directory: " + baseTrashPath, e); cause = e;
> break; }
> After catch FileAlreadyExistsException, the same name file is deleted.
> So don't modify baseTrashPath when existsFilePath is deleted.
> But this case show hardly in untitest.
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