Add option for JVM to dump its heap on OutOfMemory

Fixes #4192

Fixes #4205

Author: suyograo

bin/logstash.lib.sh

@@ -35,6 +35,11 @@ setup_java() {
 
     JAVA_OPTS="$JAVA_OPTS -XX:CMSInitiatingOccupancyFraction=75"
     JAVA_OPTS="$JAVA_OPTS -XX:+UseCMSInitiatingOccupancyOnly"
+    # Causes the JVM to dump its heap on OutOfMemory.
+    JAVA_OPTS="$JAVA_OPTS -XX:+HeapDumpOnOutOfMemoryError"
+    # The path to the heap dump location, note directory must exists and have enough
+    # space for a full heap dump.
+    JAVA_OPTS="$JAVA_OPTS -XX:HeapDumpPath=${LOGSTASH_HOME}/heapdump.hprof"
   fi
 
   if [ "$LS_JAVA_OPTS" ] ; then