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https://issues.apache.org/jira/browse/HBASE-5603?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13233824#comment-13233824
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Zhihong Yu commented on HBASE-5603:
-----------------------------------
w.r.t. http://hbase.apache.org/book.html#rolling, I think we can add more
details to it.
e.g. see the following code snippet in bin/rolling-restart.sh:
{code}
"$bin"/hbase-daemons.sh --config "${HBASE_CONF_DIR}" \
--hosts "${HBASE_BACKUP_MASTERS}" stop master-backup
{code}
bin/graceful_stop.sh is mentioned in
http://hbase.apache.org/book.html#decommission so people may not intuitively
associate it with rolling restart.
Different companies have different practices w.r.t. rolling restart.
Since rolling-restart.sh was recently enhanced to respect region placement:
{code}
r1299983 | stack | 2012-03-12 23:30:15 -0700 (Mon, 12 Mar 2012) | 1 line
HBASE-5314 racefully rolling restart region servers in rolling-restart.sh
------------------------------------------------------------------------
{code}
I think we should put it in a useable form.
> rolling-restart.sh script hangs when attempting to detect expiration of
> /hbase/master znode.
> --------------------------------------------------------------------------------------------
>
> Key: HBASE-5603
> URL: https://issues.apache.org/jira/browse/HBASE-5603
> Project: HBase
> Issue Type: Bug
> Components: zookeeper
> Affects Versions: 0.92.0, 0.94.0, 0.96.0
> Reporter: Jonathan Hsieh
> Priority: Blocker
>
> Due to bugfix ZOOKEEPER-1059 (ZK 3.4.0+), the rolling-restart.sh script will
> hang when attempting to make sure the /hbase/master znode is deleted.
> Here's the code
> {code}
> # make sure the master znode has been deleted before continuing
> zparent=`$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
> {code}
> Prior to ZOOKEEPER-1059, stat on a null znode would NPE and cause zkcli to
> exit with retcode 1. Afterwards, the null is caught, zkcli will exit with 0
> in the case where the znode is present and in the case where it does not
> exist.
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