Critical Description
We have written a batch job that uses data from HBase by means of using the TableInputFormat.
We have found that this class sometimes fails with this exception:
java.lang.RuntimeException: java.util.concurrent.RejectedExecutionException: Task org.apache.hadoop.hbase.client.ResultBoundedCompletionService$QueueingFuture@4f4efe4b rejected from java.util.concurrent.ThreadPoolExecutor@7872d5c1[Terminated, pool size = 0, active threads = 0, queued tasks = 0, completed tasks = 1165]
at org.apache.hadoop.hbase.client.RpcRetryingCaller.callWithoutRetries(RpcRetryingCaller.java:208)
at org.apache.hadoop.hbase.client.ClientScanner.call(ClientScanner.java:320)
at org.apache.hadoop.hbase.client.ClientScanner.nextScanner(ClientScanner.java:295)
at org.apache.hadoop.hbase.client.ClientScanner.initializeScannerInConstruction(ClientScanner.java:160)
at org.apache.hadoop.hbase.client.ClientScanner.<init>(ClientScanner.java:155)
at org.apache.hadoop.hbase.client.HTable.getScanner(HTable.java:821)
at org.apache.flink.addons.hbase.TableInputFormat.open(TableInputFormat.java:152)
at org.apache.flink.addons.hbase.TableInputFormat.open(TableInputFormat.java:47)
at org.apache.flink.runtime.operators.DataSourceTask.invoke(DataSourceTask.java:147)
at org.apache.flink.runtime.taskmanager.Task.run(Task.java:559)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.util.concurrent.RejectedExecutionException: Task org.apache.hadoop.hbase.client.ResultBoundedCompletionService$QueueingFuture@4f4efe4b rejected from java.util.concurrent.ThreadPoolExecutor@7872d5c1[Terminated, pool size = 0, active threads = 0, queued tasks = 0, completed tasks = 1165]
at java.util.concurrent.ThreadPoolExecutor$AbortPolicy.rejectedExecution(ThreadPoolExecutor.java:2047)
at java.util.concurrent.ThreadPoolExecutor.reject(ThreadPoolExecutor.java:823)
at java.util.concurrent.ThreadPoolExecutor.execute(ThreadPoolExecutor.java:1369)
at org.apache.hadoop.hbase.client.ResultBoundedCompletionService.submit(ResultBoundedCompletionService.java:142)
at org.apache.hadoop.hbase.client.ScannerCallableWithReplicas.addCallsForCurrentReplica(ScannerCallableWithReplicas.java:269)
at org.apache.hadoop.hbase.client.ScannerCallableWithReplicas.call(ScannerCallableWithReplicas.java:165)
at org.apache.hadoop.hbase.client.ScannerCallableWithReplicas.call(ScannerCallableWithReplicas.java:59)
at org.apache.hadoop.hbase.client.RpcRetryingCaller.callWithoutRetries(RpcRetryingCaller.java:200)
... 10 more
As you can see the ThreadPoolExecutor was terminated at this point.
We tracked it down to the fact that
- the configure method opens the table
- the open method obtains the result scanner
- the closes method closes the table.
If a second split arrives on the same instance then the open method will fail because the table has already been closed.
We also found that this error varies with the versions of HBase that are used. I have also seen this exception:
Caused by: java.io.IOException: hconnection-0x19d37183 closed
at org.apache.hadoop.hbase.client.ConnectionManager$HConnectionImplementation.locateRegion(ConnectionManager.java:1146)
at org.apache.hadoop.hbase.client.RpcRetryingCallerWithReadReplicas.getRegionLocations(RpcRetryingCallerWithReadReplicas.java:300)
... 37 more
I found that in the documentation of the InputFormat interface is clearly states
IMPORTANT NOTE: Input formats must be written such that an instance can be opened again after it was closed. That is due to the fact that the input format is used for potentially multiple splits. After a split is done, the format's close function is invoked and, if another split is available, the open function is invoked afterwards for the next split.
It appears that this specific InputFormat has not been checked against this constraint.
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