[SPARK-4832][Deploy]some other processes might take the daemon pid

Some other processes might use the pid saved in pid file. In that case we should ignore it and launch daemons.

JIRA is down for maintenance. I will file one once it return.

Author: WangTaoTheTonic <[email protected]>
Author: WangTaoTheTonic <[email protected]>

Closes apache#3683 from WangTaoTheTonic/otherproc and squashes the following commits:

daa86a1 [WangTaoTheTonic] some bash style fix
8befee7 [WangTaoTheTonic] handle the mistake scenario
cf4ecc6 [WangTaoTheTonic] remove redundant condition
f36cfb4 [WangTaoTheTonic] some other processes might take the pid

sbin/spark-daemon.sh

@@ -129,8 +129,9 @@ case $option in
     mkdir -p "$SPARK_PID_DIR"
 
     if [ -f $pid ]; then
-      if kill -0 `cat $pid` > /dev/null 2>&1; then
-        echo $command running as process `cat $pid`.  Stop it first.
+      TARGET_ID="$(cat "$pid")"
+      if [[ $(ps -p "$TARGET_ID" -o args=) =~ $command ]]; then
+        echo "$command running as process $TARGET_ID.  Stop it first."
         exit 1
       fi
     fi
@@ -141,7 +142,7 @@ case $option in
     fi
 
     spark_rotate_log "$log"
-    echo starting $command, logging to $log
+    echo "starting $command, logging to $log"
     if [ $option == spark-submit ]; then
       source "$SPARK_HOME"/bin/utils.sh
       gatherSparkSubmitOpts "$@"
@@ -154,7 +155,7 @@ case $option in
     echo $newpid > $pid
     sleep 2
     # Check if the process has died; in that case we'll tail the log so the user can see
-    if ! kill -0 $newpid >/dev/null 2>&1; then
+    if [[ ! $(ps -p "$newpid" -o args=) =~ $command ]]; then
       echo "failed to launch $command:"
       tail -2 "$log" | sed 's/^/  /'
       echo "full log in $log"
@@ -164,14 +165,15 @@ case $option in
   (stop)
 
     if [ -f $pid ]; then
-      if kill -0 `cat $pid` > /dev/null 2>&1; then
-        echo stopping $command
-        kill `cat $pid`
+      TARGET_ID="$(cat "$pid")"
+      if [[ $(ps -p "$TARGET_ID" -o args=) =~ $command ]]; then
+        echo "stopping $command"
+        kill "$TARGET_ID"
       else
-        echo no $command to stop
+        echo "no $command to stop"
       fi
     else
-      echo no $command to stop
+      echo "no $command to stop"
     fi
     ;;