HADOOP-13898. Should set HADOOP_JOB_HISTORYSERVER_HEAPSIZE only if it's empty. Contributed by Fei Hui.

hadoop-mapreduce-project/conf/mapred-env.cmd

@@ -14,7 +14,10 @@
 @rem See the License for the specific language governing permissions and
 @rem limitations under the License.
 
-set HADOOP_JOB_HISTORYSERVER_HEAPSIZE=1000
+@rem when HADOOP_JOB_HISTORYSERVER_HEAPSIZE is not defined, set it
+if not defined HADOOP_JOB_HISTORYSERVER_HEAPSIZE (
+  set HADOOP_JOB_HISTORYSERVER_HEAPSIZE=1000
+)
 
 set HADOOP_MAPRED_ROOT_LOGGER=%HADOOP_LOGLEVEL%,RFA
 

hadoop-mapreduce-project/conf/mapred-env.sh

@@ -15,7 +15,10 @@
 
 # export JAVA_HOME=/home/y/libexec/jdk1.6.0/
 
-export HADOOP_JOB_HISTORYSERVER_HEAPSIZE=1000
+# when HADOOP_JOB_HISTORYSERVER_HEAPSIZE is not defined, set it.
+if [ "$HADOOP_JOB_HISTORYSERVER_HEAPSIZE" = "" ];then
+  export HADOOP_JOB_HISTORYSERVER_HEAPSIZE=1000
+fi
 
 export HADOOP_MAPRED_ROOT_LOGGER=INFO,RFA