seekToNewSource() might not work correctly with Checksum failures.
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Key: HADOOP-1471
URL: https://issues.apache.org/jira/browse/HADOOP-1471
Project: Hadoop
Issue Type: Bug
Reporter: Raghu Angadi
Patch submitted to HADOOP-893 (by me :( ) seemhave a bug in how it deals with
the set {{deadNodes}}. After the patch, the {{seekToNewSource()}} looks like
this :
{code}
public synchronized boolean seekToNewSource(long targetPos) throws
IOException {
boolean markedDead = deadNodes.contains(currentNode);
deadNodes.add(currentNode);
DatanodeInfo oldNode = currentNode;
DatanodeInfo newNode = blockSeekTo(targetPos);
if (!markedDead) {
/* remove it from deadNodes. blockSeekTo could have cleared
* deadNodes and added currentNode again. Thats ok. */
deadNodes.remove(oldNode);
}
// ...
{code}
I guess with the expectation that caller of this function decides before the
call whether to put the node in {{deadNodes}} or not. I am not sure whether
this was a bug then or not but it certainly seems to be bug now. i.e. when
there is a checksum error with replica1, we try replica2 and if there a
checksum error again, then we try replica1 again!
Note that ChecksumFileSystem.java was created after HADOOP-893 was resolved.
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