NullPointerException from SimpleRegionNormalizer

[#1]

PROBLEM: HBase Master failing due to following exception.

2017-03-30 20:51:13,130 ERROR [<HOST NAME>,33733,1490218864063_ChoreService_3] normalizer.RegionNormalizerChore: Caught error 
java.lang.NullPointerException 
at org.apache.hadoop.hbase.master.normalizer.SimpleRegionNormalizer.getRegionSize(SimpleRegionNormalizer.java:172) 
at org.apache.hadoop.hbase.master.normalizer.SimpleRegionNormalizer.computePlanForTable(SimpleRegionNormalizer.java:99) 
at org.apache.hadoop.hbase.master.HMaster.normalizeRegions(HMaster.java:1417) 
at org.apache.hadoop.hbase.master.normalizer.RegionNormalizerChore.chore(RegionNormalizerChore.java:49) 
at org.apache.hadoop.hbase.ScheduledChore.run(ScheduledChore.java:185) 
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) 
at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:308) 
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180) 
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294) 
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) 
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) at java.lang.Thread.run(Thread.java:745)

ROOT CASUE:

https://issues.apache.org/jira/browse/HBASE-15933

WORKAROUND:

Move Splitting WAL files from hbase.root.dir (by default it set to /apps/hbase/data/WALs) to some tmp directory.