hdfs journalnode fail , Caused by: java.lang.RuntimeException: java.lang.NullPointerException

[#1]

cdh5.15

when I start journalnode, i get this. 

cmf serverlog as:

so I check heap values. Finally , I find Java Heap Size of JournalNode in Bytes is 0.

but  this value can not be set 0

Why ? why?