From 52fd70500e0a00e273e2ec0c09d7c914b89432ce Mon Sep 17 00:00:00 2001
From: tedyu <yuzhihong@gmail.com>
Date: Thu, 24 Mar 2016 06:55:45 -0700
Subject: [PATCH] HBASE-15486 Avoid multiple disable/enable balancer calls
 while running rolling-restart.sh --graceful (Samir Ahmic)

---
 bin/graceful_stop.sh   | 21 ++++++++++++++++-----
 bin/rolling-restart.sh | 10 +++++++++-
 2 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/bin/graceful_stop.sh b/bin/graceful_stop.sh
index f1f04d65254..510411eac8a 100755
--- a/bin/graceful_stop.sh
+++ b/bin/graceful_stop.sh
@@ -22,7 +22,7 @@
 # Turn off the balancer before running this script.
 function usage {
   echo "Usage: graceful_stop.sh [--config <conf-dir>] [-e] [--restart [--reload]] [--thrift] \
-[--rest] <hostname>"
+[--rest]  [-nob |--nobalancer ] <hostname>"
   echo " thrift         If we should stop/start thrift before/after the hbase stop/start"
   echo " rest           If we should stop/start rest before/after the hbase stop/start"
   echo " restart        If we should restart after graceful stop"
@@ -34,6 +34,8 @@ moving regions"
 exit with error. Default value is INT_MAX."
   echo " hostname       Hostname of server we are to stop"
   echo " e|failfast     Set -e so exit immediately if any command exits with non-zero status"
+  echo " nob| nobalancer Do not manage balancer states. This is only used as optimization in \
+rolling_restart.sh to avoid multiple calls to hbase shell"
   exit 1
 }
 
@@ -54,6 +56,7 @@ rest=
 movetimeout=2147483647
 maxthreads=1
 failfast=
+nob=false
 while [ $# -gt 0 ]
 do
   case "$1" in
@@ -65,6 +68,7 @@ do
     --noack | -n)  noack="--noack"; shift;;
     --maxthreads) shift; maxthreads=$1; shift;;
     --movetimeout) shift; movetimeout=$1; shift;;
+    --nobalancer | -nob) nob=true; shift;;
     --) shift; break;;
     -*) usage ;;
     *)  break;;	# terminate while loop
@@ -97,9 +101,14 @@ if [ "$localhostname" == "$hostname" ]; then
   local=true
 fi
 
-log "Disabling load balancer"
-HBASE_BALANCER_STATE=`echo 'balance_switch false' | "$bin"/hbase --config ${HBASE_CONF_DIR} shell | tail -3 | head -1`
-log "Previous balancer state was $HBASE_BALANCER_STATE"
+if [ $nob == "true"  ]; then
+  log "[ $0 ] skipping disabling balancer -nob argument is used"
+  HBASE_BALANCER_STATE=false
+else
+  log "Disabling load balancer"
+  HBASE_BALANCER_STATE=$(echo 'balance_switch false' | "$bin"/hbase --config "${HBASE_CONF_DIR}" shell | tail -3 | head -1)
+  log "Previous balancer state was $HBASE_BALANCER_STATE"
+fi
 
 log "Unloading $hostname region(s)"
 HBASE_NOEXEC=true "$bin"/hbase --config ${HBASE_CONF_DIR} org.apache.hadoop.hbase.util.RegionMover \
@@ -166,9 +175,11 @@ if [ "$restart" != "" ]; then
 fi
 
 # Restore balancer state
-if [ $HBASE_BALANCER_STATE != "false" ]; then
+if [ $HBASE_BALANCER_STATE != "false" ] && [ $nob != "true"  ]; then
   log "Restoring balancer state to $HBASE_BALANCER_STATE"
   echo "balance_switch $HBASE_BALANCER_STATE" | "$bin"/hbase --config ${HBASE_CONF_DIR} shell &> /dev/null
+else
+  log "[ $0 ] skipping restoring balancer"
 fi
 
 # Cleanup tmp files.
diff --git a/bin/rolling-restart.sh b/bin/rolling-restart.sh
index e6d25edb4ec..530b76ba346 100755
--- a/bin/rolling-restart.sh
+++ b/bin/rolling-restart.sh
@@ -188,6 +188,10 @@ else
     if [ "$zkrs" == "null" ]; then zkrs="rs"; fi
     zkrs="$zparent/$zkrs"
     online_regionservers=`$bin/hbase zkcli ls $zkrs 2>&1 | tail -1 | sed "s/\[//" | sed "s/\]//"`
+    echo "Disabling load balancer"
+    HBASE_BALANCER_STATE=$(echo 'balance_switch false' | "$bin"/hbase --config "${HBASE_CONF_DIR}" shell | tail -3 | head -1)
+    echo "Previous balancer state was $HBASE_BALANCER_STATE"
+
     for rs in $online_regionservers
     do
         rs_parts=(${rs//,/ })
@@ -198,10 +202,14 @@ else
           continue
         else
           echo "Gracefully restarting: $hostname"
-          "$bin"/graceful_stop.sh --config ${HBASE_CONF_DIR} --restart --reload --maxthreads \
+          "$bin"/graceful_stop.sh --config ${HBASE_CONF_DIR} --restart --reload -nob --maxthreads  \
 		${RR_MAXTHREADS} ${RR_NOACK} --movetimeout ${RR_MOVE_TIMEOUT} $hostname
           sleep 1
         fi
     done
+    if [ "$HBASE_BALANCER_STATE" != "false" ]; then
+      echo "Restoring balancer state to $HBASE_BALANCER_STATE"
+      echo "balance_switch $HBASE_BALANCER_STATE" | "$bin"/hbase --config "${HBASE_CONF_DIR}" shell &> /dev/null
+    fi
   fi
 fi