I looked at the patch for ZOOKEEPER-1059 which should have converted the
NPE to KeeperException.NoNodeException
Why would 'zkcli stat' command return 0 in case hbase master znode expires ?
Advice is appreciated.
FYI Jon filed a JIRA for the issue below which is a blocker for HBase trunk.
On Tue, Mar 20, 2012 at 12:36 AM, Jonathan Hsieh <j...@cloudera.com> wrote:
> I'm trying to test HBASE-5589 -- to see if I can add an API call to
> HMasterInterface and do a rolling-restart / upgrade on a live cluster which
> lead me down another rabbit hole.
>
> I'm wondering how rolling-restart.sh script worked in the past (I can spend
> more time setting up an older version to test this, but figured I'd ask).
>
> I'm getting stuck when the bin/rolling-restart.sh tries to wait until the
> Master ZNode expires. In this particular case, the script seems to hang
> there forever (even after the /hbase/master ephemeral node expires).
>
> Here's the code in the script:
> ----
> # make sure the master znode has been deleted before continuing
> zparent=`$bin/hbase org.apache.hadoop.hbase.util.HBaseConfTool
> zookeeper.znode.parent`
> if [ "$zparent" == "null" ]; then zparent="/hbase"; fi
> zmaster=`$bin/hbase org.apache.hadoop.hbase.util.HBaseConfTool
> zookeeper.znode.master`
> if [ "$zmaster" == "null" ]; then zmaster="master"; fi
> zmaster=$zparent/$zmaster
> echo -n "Waiting for Master ZNode ${zmaster} to expire"
> while bin/hbase zkcli stat $zmaster >/dev/null 2>&1; do
> echo -n "."
> sleep 1
> done
> echo #force a newline
> ----
>
> The problem is that 'bin/hbase zkcli stat /hbase/master ...' seems to
> always returns with $? == 0 regardless if the znode is present or not
> present! I've checked with Patrick Hunt (ZK committer) and this the
> expected behavior. The only non-zero retcodes are for abnormal exits
> (exceptions thrown)
>
> Here's the ZK code I was looking through
>
> https://github.com/apache/zookeeper/blob/release-3.4.3/src/java/main/org/apache/zookeeper/ZooKeeperMain.java#L736
>
>
> https://github.com/apache/zookeeper/blob/release-3.4.3/src/java/main/org/apache/zookeeper/ZooKeeper.java#L980
>
>
> Thoughts?
>
> Jon.
>
> --
> // Jonathan Hsieh (shay)
> // Software Engineer, Cloudera
> // j...@cloudera.com
>
