surendra singh lilhore created HDFS-3386:
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Summary: Namenode is not deleting his lock entry
'/ledgers/lock/lock-0000X', when fails to acquire the lock
Key: HDFS-3386
URL: https://issues.apache.org/jira/browse/HDFS-3386
Project: Hadoop HDFS
Issue Type: Bug
Components: ha
Reporter: surendra singh lilhore
Priority: Minor
Fix For: 0.23.0
When a Standby NN becomes Active, it will first create his sequential lock
entry create lock-000X in ZK and then tries to acquire the lock as shown below:
{quote}
myznode = zkc.create(lockpath + "/lock-", new byte[] {'0'},
Ids.OPEN_ACL_UNSAFE,
CreateMode.EPHEMERAL_SEQUENTIAL);
if ((lockpath + "/" + nodes.get(0)).equals(myznode)) {
if (LOG.isTraceEnabled()) {
LOG.trace("Lock acquired - " + myznode);
}
lockCount.set(1);
zkc.exists(myznode, this);
return;
} else {
LOG.error("Failed to acquire lock with " + myznode
+ ", " + nodes.get(0) + " already has it");
throw new IOException("Could not acquire lock");
}
{quote}
Say the transition to standby fails to acquire the lock it will throw the
exception and NN is getting shutdown. Here the problem is, the lock entry
lock-000X will exists in the ZK till session expiry and the further start-up
will not be able to acquire lock.
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