HDDS-3173. Provide better default JVM options

Closes #710

hadoop-ozone/dist/src/shell/hdds/hadoop-functions.sh

@@ -1541,6 +1541,21 @@ function hadoop_translate_cygwin_path
   fi
 }
 
+## @description  Adds default GC parameters
+## @description  Only for server components and only if no other -XX parameters
+## @description  are set
+## @audience     private
+## @stability    evolving
+## @replaceable  yes
+function hadoop_add_default_gc_opts
+{
+  if [[ "${HADOOP_SUBCMD_SUPPORTDAEMONIZATION}" == true ]]; then
+    if [[ ! "$HADOOP_OPTS" =~ "-XX" ]] ; then
+       hadoop_error "No '-XX:...' jvm parameters are used. Adding safer GC settings to the HADOOP_OPTS"
+       HADOOP_OPTS="${HADOOP_OPTS} -XX:ParallelGCThreads=8 -XX:+UseConcMarkSweepGC -XX:CMSInitiatingOccupancyFraction=70 -XX:+CMSParallelRemarkEnabled"
+    fi
+  fi
+}
 ## @description  Adds the HADOOP_CLIENT_OPTS variable to
 ## @description  HADOOP_OPTS if HADOOP_SUBCMD_SUPPORTDAEMONIZATION is false
 ## @audience     public

hadoop-ozone/dist/src/shell/ozone/ozone

@@ -305,6 +305,8 @@ IFS=$OIFS
 
 hadoop_add_client_opts
 
+hadoop_add_default_gc_opts
+
 if [[ ${HADOOP_WORKER_MODE} = true ]]; then
   hadoop_common_worker_mode_execute "${HADOOP_HDFS_HOME}/bin/ozone" "${HADOOP_USER_PARAMS[@]}"
   exit $?

hadoop-ozone/dist/src/test/shell/gc_opts.bats

@@ -0,0 +1,44 @@
+#!/usr/bin/env bash
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to You under the Apache License, Version 2.0
+# (the "License"); you may not use this file except in compliance with
+# the License.  You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+
+#
+# Can be executed with bats (https://github.com/bats-core/bats-core)
+# bats gc_opts.bats (FROM THE CURRENT DIRECTORY)
+#
+
+source ../../shell/hdds/hadoop-functions.sh
+@test "Setting Hadoop GC parameters: add GC params for server" {
+  export HADOOP_SUBCMD_SUPPORTDAEMONIZATION=true
+  export HADOOP_OPTS="Test"
+  hadoop_add_default_gc_opts
+  [[ "$HADOOP_OPTS" =~ "UseConcMarkSweepGC" ]]
+}
+
+@test "Setting Hadoop GC parameters: disabled for client" {
+  export HADOOP_SUBCMD_SUPPORTDAEMONIZATION=false
+  export HADOOP_OPTS="Test"
+  hadoop_add_default_gc_opts
+  [[ ! "$HADOOP_OPTS" =~ "UseConcMarkSweepGC" ]]
+}
+
+@test "Setting Hadoop GC parameters: disabled if GC params are customized" {
+  export HADOOP_SUBCMD_SUPPORTDAEMONIZATION=true
+  export HADOOP_OPTS="-XX:++UseG1GC -Xmx512"
+  hadoop_add_default_gc_opts
+  [[ ! "$HADOOP_OPTS" =~ "UseConcMarkSweepGC" ]]
+}