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Flume, mail # user - flume agent with HDFS sink, syslog source and memory channel - stuck on hdfs IOException


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Re: flume agent with HDFS sink, syslog source and memory channel - stuck on hdfs IOException
Roshan Naik 2013-10-15, 20:15
Paul,
   HDFS sink issue apart... it sounds like this is a setup where  Hive  s
being allowed to read through new files/directories flowing into the
partition while HDFS sink is still writing to it. To my knowledge, in Hive,
a partition is considered immutable and it should not be updated once the
partition is created. So only once the HDFS sink has rolled over to the
next directory, the previous directory should be exposed to Hive.
-roshan
On Tue, Oct 15, 2013 at 11:23 AM, Paul Chavez <
[EMAIL PROTECTED]> wrote:

> I can’t speak for Suhas, but I face a similar issue in production. For me
> it occurs when someone queries a .tmp file from Hive or Pig. This causes
> the HDFS sink to lose the ability to close and rename the file and then the
> HDFS sink is completely out of commission until the agent is restarted.
> We’ve mitigated this in our environment by careful Hive partition
> coordination but it still crops up in cases where people are running ad-hoc
> queries they probably shouldn’t be. We are waiting to get the latest CDH in
> production which eliminates the .tmp file issue but I would still like to
> have a more resilient HDFS sink and so I support development effort in this
> area.****
>
> ** **
>
> Thanks,****
>
> Paul Chavez****
>
> ** **
>
> ** **
>
> *From:* Roshan Naik [mailto:[EMAIL PROTECTED]]
> *Sent:* Tuesday, October 15, 2013 11:14 AM
> *To:* [EMAIL PROTECTED]
> *Cc:* [EMAIL PROTECTED]; [EMAIL PROTECTED]
> *Subject:* Re: flume agent with HDFS sink, syslog source and memory
> channel - stuck on hdfs IOException****
>
> ** **
>
> sounds like a valid bug. i am curious though... is there a use real use
> scenario you are facing in production ?****
>
> ** **
>
> On Mon, Oct 14, 2013 at 7:39 PM, Suhas Satish <[EMAIL PROTECTED]>
> wrote:****
>
> In summary, although the flume-agent JVM doesnt exit, once a HDFS IO
> exception
> occurs due to deleting a .tmp file, the agent doesn't recover from this to
> log
> other hdfs sink outputs generated by syslog source.
>
> There was only 1 JIRA remotely related to this HDFS sink issue I found in
> Apache which we didn't have. I tested by pulling-in jira patch
> FLUME-2007 into flume-1.4.0.
>
> https://github.com/apache/flume/commit/5b5470bd5d3e94842032009c36788d4ae346674bhttps://issues.apache.org/jira/browse/FLUME-2007<https://github.com/apache/flume/commit/5b5470bd5d3e94842032009c36788d4ae346674bhttps:/issues.apache.org/jira/browse/FLUME-2007>
>
> But it doesn't solve this issue.
>
> Should I open a new jira ticket?
>
>
>
> Thanks,
> Suhas.
>
>
> On Fri, Oct 11, 2013 at 4:13 PM, Suhas Satish <[EMAIL PROTECTED]
> >wrote:****
>
>
> > Hi I have the  following flume configuration file   flume-syslog.conf
> > (attached) -
> >
> > 1.) I laucnh it with -
> >
> > bin/flume-ng agent -n agent -c conf -f conf/flume-syslog.conf
> >
> > 2.) Generate log output using loggen (provided by syslog-ng):
> > loggen -I 30 -s 300 -r 900 localhost 13073
> >
> > 3.) I verify flume output is generated under /flume_import/ on hadoop
> cluster.
> >
> > It generates output of the form -
> >
> > -rwxr-xr-x   3 root root     139235 2013-10-11 14:35
> > /flume_import/2013/10/14/logdata-2013-10-14-35-45.1381527345384.tmp
> > -rwxr-xr-x   3 root root     138095 2013-10-11 14:35
> > /flume_import/2013/10/14/logdata-2013-10-14-35-46.1381527346543.tmp
> > -rwxr-xr-x   3 root root     135795 2013-10-11 14:35
> > /flume_import/2013/10/14/logdata-2013-10-14-35-47.1381527347670.tmp
> >
> >
> > 4.)  Delete the flume output files while loggen is still running and
> Flume is
> > generating the sink output.
> >
> > hadoop fs -rmr
> /flume_import/2013/10/14/logdata-2013-10-14-35-47.1381527347670.tmp
> >
> > 5. )This  gives me the following exception in the flume log. Although
> the flume agent JVM continues to run, it does not generate any more output
> files from syslog-ng  until the flume agent JVM is restarted. Is flume
>  expected to behave like this or  should it handle IOException gracefully

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