NPE FullBoltMetrics.ackedTuple

[thinker0]

• heron-0.18.7

[2018-11-09 00:13:28 +0900] [SEVERE] monitor: Exception propagated to the root monitor! 
java.lang.NullPointerException
	at com.twitter.heron.common.utils.metrics.FullBoltMetrics.ackedTuple(FullBoltMetrics.java:127)
	at com.twitter.heron.instance.bolt.BoltOutputCollectorImpl.admitAckTuple(BoltOutputCollectorImpl.java:159)
	at com.twitter.heron.instance.bolt.BoltOutputCollectorImpl.ack(BoltOutputCollectorImpl.java:91)
	at com.twitter.heron.api.bolt.OutputCollector.ack(OutputCollector.java:234)
	at org.apache.storm.task.OutputCollectorImpl.ack(OutputCollectorImpl.java:76)

[2018-11-09 00:13:06 +0900] [SEVERE] com.twitter.heron.instance.HeronInstance: Exception caught in thread: SlaveThread with id: 24 
java.lang.NullPointerException
	at com.twitter.heron.proto.system.HeronTuples$HeronControlTupleSet.isInitialized(HeronTuples.java:4158)
	at com.twitter.heron.proto.system.HeronTuples$HeronControlTupleSet$Builder.build(HeronTuples.java:4423)
	at com.twitter.heron.proto.system.HeronTuples$HeronTupleSet$Builder.setControl(HeronTuples.java:6144)
	at com.twitter.heron.instance.OutgoingTupleCollection.flushRemaining(OutgoingTupleCollection.java:193)
	at com.twitter.heron.instance.OutgoingTupleCollection.sendOutTuples(OutgoingTupleCollection.java:85)
	at com.twitter.heron.instance.AbstractOutputCollector.sendOutTuples(AbstractOutputCollector.java:102)
	at com.twitter.heron.instance.bolt.BoltInstance$1.run(BoltInstance.java:212)
	at com.twitter.heron.common.basics.WakeableLooper.executeTasksOnWakeup(WakeableLooper.java:186)
	at com.twitter.heron.common.basics.WakeableLooper.runOnce(WakeableLooper.java:105)
	at com.twitter.heron.common.basics.WakeableLooper.loop(WakeableLooper.java:95)
	at com.twitter.heron.instance.Slave.run(Slave.java:180)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:748)