RejectedExecutionException could be thrown from TableOverAsyncTable.coprocessor service if the connection has been shutown

2019-06-01 00:40:09,104 ERROR [PEWorker-13] procedure2.ProcedureExecutor(1667): CODE-BUG: Uncaught runtime exception: pid=9, state=RUNNABLE:MERGE_TABLE_REGIONS_UPDATE_META, hasLock=true; MergeTableRegionsProcedure table=test, regions=[048d06685b8e1df26516884c41b59c9b, 9f7c60e69f7144b32deb828e3a60c8a8], forcibly=false
java.util.concurrent.RejectedExecutionException: Task java.util.concurrent.FutureTask@4ba1959e rejected from java.util.concurrent.ThreadPoolExecutor@67913a08[Terminated, pool size = 0, active threads = 0, queued tasks = 0, completed tasks = 0]
	at java.util.concurrent.ThreadPoolExecutor$AbortPolicy.rejectedExecution(ThreadPoolExecutor.java:2063)
	at java.util.concurrent.ThreadPoolExecutor.reject(ThreadPoolExecutor.java:830)
	at java.util.concurrent.ThreadPoolExecutor.execute(ThreadPoolExecutor.java:1379)
	at java.util.concurrent.AbstractExecutorService.submit(AbstractExecutorService.java:134)
	at org.apache.hadoop.hbase.client.TableOverAsyncTable.coprocssorService(TableOverAsyncTable.java:427)
	at org.apache.hadoop.hbase.client.TableOverAsyncTable.coprocessorService(TableOverAsyncTable.java:457)
	at org.apache.hadoop.hbase.client.Table.coprocessorService(Table.java:527)
	at org.apache.hadoop.hbase.MetaTableAccessor.multiMutate(MetaTableAccessor.java:1768)
	at org.apache.hadoop.hbase.MetaTableAccessor.mergeRegions(MetaTableAccessor.java:1634)
	at org.apache.hadoop.hbase.master.assignment.RegionStateStore.mergeRegions(RegionStateStore.java:253)
	at org.apache.hadoop.hbase.master.assignment.AssignmentManager.markRegionAsMerged(AssignmentManager.java:1665)
	at org.apache.hadoop.hbase.master.assignment.MergeTableRegionsProcedure.updateMetaForMergedRegions(MergeTableRegionsProcedure.java:731)
	at org.apache.hadoop.hbase.master.assignment.MergeTableRegionsProcedure.executeFromState(MergeTableRegionsProcedure.java:276)
	at org.apache.hadoop.hbase.master.assignment.MergeTableRegionsProcedure.executeFromState(MergeTableRegionsProcedure.java:84)
	at org.apache.hadoop.hbase.procedure2.StateMachineProcedure.execute(StateMachineProcedure.java:194)
	at org.apache.hadoop.hbase.procedure2.Procedure.doExecute(Procedure.java:959)
	at org.apache.hadoop.hbase.procedure2.ProcedureExecutor.execProcedure(ProcedureExecutor.java:1648)
	at org.apache.hadoop.hbase.procedure2.ProcedureExecutor.executeProcedure(ProcedureExecutor.java:1395)
	at org.apache.hadoop.hbase.procedure2.ProcedureExecutor.access$1100(ProcedureExecutor.java:78)
	at org.apache.hadoop.hbase.procedure2.ProcedureExecutor$WorkerThread.run(ProcedureExecutor.java:1964)