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From Chesnay Schepler <ches...@apache.org>
Subject Re: Issue with running Flink Python jobs on cluster
Date Fri, 15 Jul 2016 08:15:28 GMT
Could you write a java job that uses the Distributed cache to distribute 
files?

If this fails then the DC is faulty, if it doesn't something in the 
Python API is wrong.

On 15.07.2016 08:06, Geoffrey Mon wrote:
> I've come across similar issues when trying to set up Flink on Amazon 
> EC2 instances. Presumably there is something wrong with my setup? Here 
> is the flink-conf.yaml I am using:
> https://gist.githubusercontent.com/GEOFBOT/3ffc9b21214174ae750cc3fdb2625b71/raw/flink-conf.yaml
>
> Thanks,
> Geoffrey
>
> On Wed, Jul 13, 2016 at 1:15 PM Geoffrey Mon <geofbot@gmail.com 
> <mailto:geofbot@gmail.com>> wrote:
>
>     Hello,
>
>     Here is the TaskManager log on pastebin:
>     http://pastebin.com/XAJ56gn4
>
>     I will look into whether the files were created.
>
>     By the way, the cluster is made with virtual machines running on
>     BlueData EPIC. I don't know if that might be related to the problem.
>
>     Thanks,
>     Geoffrey
>
>
>     On Wed, Jul 13, 2016 at 6:12 AM Chesnay Schepler
>     <chesnay@apache.org <mailto:chesnay@apache.org>> wrote:
>
>         Hello Geoffrey,
>
>         How often does this occur?
>
>         Flink distributes the user-code and the python library using
>         the Distributed Cache.
>
>         Either the file is deleted right after being created for some
>         reason, or the DC returns a file name before the file was
>         created (which shouldn't happen, it should block it is available).
>
>         If you are up to debugging this i would suggest looking into
>         FileCache class and verifying whether the file in question is
>         in fact created.
>
>         The logs of the TaskManager of which the exception occurs
>         could be of interest too; could you send them to me?
>
>         Regards,
>         Chesnay
>
>
>         On 13.07.2016 04:11, Geoffrey Mon wrote:
>>         Hello all,
>>
>>         I've set up Flink on a very small cluster of one master node
>>         and five worker nodes, following the instructions in the
>>         documentation
>>         (https://ci.apache.org/projects/flink/flink-docs-master/setup/cluster_setup.html).
>>         I can run the included examples like WordCount and PageRank
>>         across the entire cluster, but when I try to run simple
>>         Python examples, I sometimes get a strange error on the first
>>         PythonMapPartition about the temporary folders that contain
>>         the streams of data between Python and Java.
>>
>>         If I run jobs on only the taskmanager on the master node,
>>         Python examples run fine. However, if the jobs use the worker
>>         nodes, then I get the following error:
>>
>>         org.apache.flink.client.program.ProgramInvocationException:
>>         The program execution failed: Job execution failed.
>>         at
>>         org.apache.flink.client.program.ClusterClient.run(ClusterClient.java:378)
>>         <snip>
>>         Caused by:
>>         org.apache.flink.runtime.client.JobExecutionException: Job
>>         execution failed.
>>         at
>>         org.apache.flink.runtime.jobmanager.JobManager$$anonfun$handleMessage$1$$anonfun$applyOrElse$7.apply$mcV$sp(JobManager.scala:806)
>>         <snip>
>>         Caused by: java.lang.Exception: The user defined 'open()'
>>         method caused an exception: External process for task
>>         MapPartition (PythonMap) terminated prematurely.
>>         python: can't open file
>>         '/home/bluedata/flink/tmp/flink-dist-cache-d1958549-3d58-4554-b286-cb4b1cdb9060/52feefa8892e61ba9a187f7684c84ada/flink/plan.py':
>>         [Errno 2] No such file or directory
>>         at
>>         org.apache.flink.runtime.operators.BatchTask.run(BatchTask.java:481)
>>         <snip>
>>         Caused by: java.lang.RuntimeException: External process for
>>         task MapPartition (PythonMap) terminated prematurely.
>>         python: can't open file
>>         '/home/bluedata/flink/tmp/flink-dist-cache-d1958549-3d58-4554-b286-cb4b1cdb9060/52feefa8892e61ba9a187f7684c84ada/flink/plan.py':
>>         [Errno 2] No such file or directory
>>         at
>>         org.apache.flink.python.api.streaming.data.PythonStreamer.startPython(PythonStreamer.java:144)
>>         at
>>         org.apache.flink.python.api.streaming.data.PythonStreamer.open(PythonStreamer.java:92)
>>         at
>>         org.apache.flink.python.api.functions.PythonMapPartition.open(PythonMapPartition.java:48)
>>         at
>>         org.apache.flink.api.common.functions.util.FunctionUtils.openFunction(FunctionUtils.java:38)
>>         at
>>         org.apache.flink.runtime.operators.BatchTask.run(BatchTask.java:477)
>>         ... 5 more
>>
>>         I'm suspecting this issue has something to do with the data
>>         sending between the master and the workers, but I haven't
>>         been able to find any solutions. Presumably the temporary
>>         files weren't received properly and thus were not created
>>         properly?
>>
>>         Thanks in advance.
>>
>>         Cheers,
>>         Geoffrey
>


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