Hi,
I would speculate that the reason for this order is that we want to shutdown
the tasks quickly by interrupting blocking calls in the event of failure, so
that recover can begin as fast as possible. I am looping in Stephan who might
give more details about this code.
Best,
Stefan
> Am 27.09.2017 um 07:33 schrieb wangsan <wamg...@163.com>:
>
> After digging into the source code, we found that when Flink job is canceled,
> a TaskCanceler thread is created.
>
> The TaskCanceler thread calls cancel() on the invokable and periodically
> interrupts the
> task thread until it has terminated.
>
> try {
> invokable.cancel();
> } catch (Throwable t) {
> logger.error("Error while canceling the task {}.", taskName, t);
> }//......executer.interrupt();try {
> executer.join(interruptInterval);
> }catch (InterruptedException e) { // we can ignore this}//......
> Notice that TaskCanceler first send interrupt signal to task thread, and
> following with join method. And since the task thread is now try to close
> DFSOutputStream, which is waiting for ack, thus InterruptedException is
> throwed out in task thread.
>
> synchronized (dataQueue) {while (!streamerClosed) {
> checkClosed(); if (lastAckedSeqno >= seqno) { break;
> } try {
> dataQueue.wait(1000); // when we receive an ack, we notify on
> // dataQueue
> } catch (InterruptedException ie) { throw new InterruptedIOException(
> "Interrupted while waiting for data to be acknowledged by pipeline");
> }
> }
> I was confused why TaskCanceler call executer.interrupt() before
> executer.join(interruptInterval). Can anyone help?
>
>
>
>
>
>
> Hi,
>
> We are currently using BucketingSink to save data into HDFS in parquet
> format. But when the flink job was cancelled, we always got Exception in
> BucketingSink's close method. The datailed exception info is as below:
> [ERROR] [2017-09-26 20:51:58,893]
> [org.apache.flink.streaming.runtime.tasks.StreamTask] - Error during disposal
> of stream operator.
> java.io.InterruptedIOException: Interrupted while waiting for data to be
> acknowledged by pipeline
> at
> org.apache.hadoop.hdfs.DFSOutputStream.waitForAckedSeqno(DFSOutputStream.java:2151)
> at
> org.apache.hadoop.hdfs.DFSOutputStream.flushInternal(DFSOutputStream.java:2130)
> at
> org.apache.hadoop.hdfs.DFSOutputStream.closeImpl(DFSOutputStream.java:2266)
> at
> org.apache.hadoop.hdfs.DFSOutputStream.close(DFSOutputStream.java:2236)
> at
> org.apache.hadoop.fs.FSDataOutputStream$PositionCache.close(FSDataOutputStream.java:72)
> at
> org.apache.hadoop.fs.FSDataOutputStream.close(FSDataOutputStream.java:106)
> at
> org.apache.parquet.hadoop.ParquetFileWriter.end(ParquetFileWriter.java:643)
> at
> org.apache.parquet.hadoop.InternalParquetRecordWriter.close(InternalParquetRecordWriter.java:117)
> at org.apache.parquet.hadoop.ParquetWriter.close(ParquetWriter.java:301)
> .......
> at
> org.apache.flink.api.common.functions.util.FunctionUtils.closeFunction(FunctionUtils.java:43)
> at
> org.apache.flink.streaming.api.operators.AbstractUdfStreamOperator.dispose(AbstractUdfStreamOperator.java:126)
> at
> org.apache.flink.streaming.runtime.tasks.StreamTask.disposeAllOperators(StreamTask.java:429)
> at
> org.apache.flink.streaming.runtime.tasks.StreamTask.invoke(StreamTask.java:334)
> at org.apache.flink.runtime.taskmanager.Task.run(Task.java:702)
> at java.lang.Thread.run(Thread.java:745)
>
> It seems that DFSOutputStream haven't been closed before task thread is force
> terminated. We found a similar problem in
> http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/Changing-timeout-for-cancel-command-td12601.html
>
> <http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/Changing-timeout-for-cancel-command-td12601.html,>
> , but setting "akka.ask.timeout" to a larger value does not work for us. So
> how can we make sure the stream is safely closed when cacelling a job?
>
> Best,
> wangsan
>
>
>
>
>
