spark instance number must be present in log filename to prevent multiple workers from overriding each other's logs

bin/spark-daemon.sh

@@ -94,9 +94,9 @@ if [ "$SPARK_PID_DIR" = "" ]; then
 fi
 
 # some variables
-export SPARK_LOGFILE=spark-$SPARK_IDENT_STRING-$command-$HOSTNAME.log
+export SPARK_LOGFILE=spark-$SPARK_IDENT_STRING-$command-$instance-$HOSTNAME.log
 export SPARK_ROOT_LOGGER="INFO,DRFA"
-log=$SPARK_LOG_DIR/spark-$SPARK_IDENT_STRING-$command-$HOSTNAME.out
+log=$SPARK_LOG_DIR/spark-$SPARK_IDENT_STRING-$command-$instance-$HOSTNAME.out
 pid=$SPARK_PID_DIR/spark-$SPARK_IDENT_STRING-$command-$instance.pid
 
 # Set default scheduling priority