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https://issues.apache.org/jira/browse/HDFS-12832?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16263282#comment-16263282
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Konstantin Shvachko edited comment on HDFS-12832 at 11/22/17 8:18 PM:
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The 002 patch fixes the issue of calling {{getFullPathName()}} without holding
the lock. The fix is to compute {{getFullPathName()}} inside
{{BlockReconstructionWork}} constructor, which is called under the lock. Just
as explained earlier.
I did not write a unit test as we would have to perform a major surgery on
FSNamesystem in order to get exactly that {{ArrayIndexOutOfBoundsException}}.
Instead I looked through all calls of {{getFullPathName()}}, making sure it is
done under a lock. Found one place where it is not - in Fsck. Will file a jira
for that shortly.
was (Author: shv):
The 002 patch fixes the issue of calling {{getFullPathName()}} without holding
the lock. The fix is to compute {{getFullPathName()}} inside
{{BlockReconstructionWork}} constructor, which is called under the lock. Just
as explained earlier.
I did not write a unit as we would have to perform a major surgery on
FSNamesystem in order to get exacvtly that {{ArrayIndexOutOfBoundsException}}.
Instead I loo0ked through all calls of {{getFullPathName()}}, making sure it is
done under a lock. Found one place where it is not - in Fsck. Will file a jira
for that shortly.
> INode.getFullPathName may throw ArrayIndexOutOfBoundsException lead to
> NameNode exit
> ------------------------------------------------------------------------------------
>
> Key: HDFS-12832
> URL: https://issues.apache.org/jira/browse/HDFS-12832
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: namenode
> Affects Versions: 2.7.4, 3.0.0-beta1
> Reporter: DENG FEI
> Priority: Critical
> Labels: release-blocker
> Attachments: HDFS-12832-trunk-001.patch, HDFS-12832.002.patch,
> exception.log
>
>
> {code:title=INode.java|borderStyle=solid}
> public String getFullPathName() {
> // Get the full path name of this inode.
> if (isRoot()) {
> return Path.SEPARATOR;
> }
> // compute size of needed bytes for the path
> int idx = 0;
> for (INode inode = this; inode != null; inode = inode.getParent()) {
> // add component + delimiter (if not tail component)
> idx += inode.getLocalNameBytes().length + (inode != this ? 1 : 0);
> }
> byte[] path = new byte[idx];
> for (INode inode = this; inode != null; inode = inode.getParent()) {
> if (inode != this) {
> path[--idx] = Path.SEPARATOR_CHAR;
> }
> byte[] name = inode.getLocalNameBytes();
> idx -= name.length;
> System.arraycopy(name, 0, path, idx, name.length);
> }
> return DFSUtil.bytes2String(path);
> }
> {code}
> We found ArrayIndexOutOfBoundsException at
> _{color:#707070}System.arraycopy(name, 0, path, idx, name.length){color}_
> when ReplicaMonitor work ,and the NameNode will quit.
> It seems the two loop is not synchronized, the path's length is changed.
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