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Kafka >> mail # user >> Kafka broker not respecting log.roll.hours?


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Dan Frankowski 2013-04-25, 19:45
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Jun Rao 2013-04-26, 04:49
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Dan Frankowski 2013-04-26, 06:13
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Jun Rao 2013-04-26, 14:40
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Dan Frankowski 2013-04-26, 15:20
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Re: Kafka broker not respecting log.roll.hours?
By the way, is there a reason why 'log.roll.hours' is not documented on the
apache configuration page:  http://kafka.apache.org/configuration.html ?

It's possible to find this setting (and several other undocumented
settings) by looking at the source code.  I'm just not sure why the
complete set of options is not documented on the site (is it meant to be
experimental?).

Jason
On Fri, Apr 26, 2013 at 8:19 AM, Dan Frankowski <[EMAIL PROTECTED]> wrote:

> https://issues.apache.org/jira/browse/KAFKA-881
>
> Thanks.
>
>
> On Fri, Apr 26, 2013 at 7:40 AM, Jun Rao <[EMAIL PROTECTED]> wrote:
>
> > Yes, for low volume topic, the time-based rolling can be imprecise. Could
> > you file a jira and describe your suggestions there? Ideally, we should
> set
> > firstAppendTime to the file creation time. However, it doesn't seem you
> can
> > get the creation time in java.
> >
> > Thanks,
> >
> > Jun
> >
> >
> > On Thu, Apr 25, 2013 at 11:12 PM, Dan Frankowski <[EMAIL PROTECTED]>
> > wrote:
> >
> > > We have high-volume topics and low-volume topics. The problem occurs
> more
> > > often for low-volume topics to be sure.
> > >
> > > But if my hypothesis is correct about why it is happening, here is a
> case
> > > where rolling is longer than an hour, even on a high volume topic:
> > >
> > > - write to a topic for 20 minutes
> > > - restart the broker
> > > - wait for 5 days
> > > - write to a topic for 20 minutes
> > > - restart the broker
> > > - write to a topic for an hour
> > >
> > > The rollover time was now 5 days, 1 hour, 40 minutes. You can make it
> as
> > > long as you want. Does this make sense?
> > >
> > > We would like the rollover time to be no more than an hour, even if the
> > > broker is restarted, or the topic is low-volume.
> > >
> > > The cleanest way to do that might be to roll over on the hour no matter
> > > when the file was started. That would be too fast sometimes, but that's
> > > fine. A second way would be to embed the first append time in the file
> > > name. A third way (not perfect, but an approximation at least) would be
> > to
> > > not to write to a segment if firstAppendTime is not defined and the
> > > timestamp on the file is more than an hour old. There are probably
> other
> > > ways.
> > >
> > > What say you?
> > >
> > >
> > > On Thu, Apr 25, 2013 at 9:49 PM, Jun Rao <[EMAIL PROTECTED]> wrote:
> > >
> > > > That logic in 0.7.2 seems correct. Basically, firstAppendTime is set
> on
> > > > first append to a log segment. Then, later on, when a new message is
> > > > appended and the elapsed time since firstAppendTime is larger than
> the
> > > roll
> > > > time, a new segment is rolled. Is your data constantly being
> produced?
> > > >
> > > > Thanks,
> > > >
> > > > Jun
> > > >
> > > >
> > > > On Thu, Apr 25, 2013 at 12:44 PM, Dan Frankowski <[EMAIL PROTECTED]
> >
> > > > wrote:
> > > >
> > > > > We are running Kafka 0.7.2. We set log.roll.hours=1. I hoped that
> > meant
> > > > > logs would be rolled every hour, or more. Only, sometimes logs that
> > are
> > > > > many hours (sometimes days) old have more data added to them. This
> > > > perturbs
> > > > > our systems for reasons I won't get in to.
> > > > >
> > > > > Have others observed this? Is it a bug? Is there a planned fix?
> > > > >
> > > > > I don't know Scala or Kafka well, but I have proposal for why this
> > > might
> > > > > happen: upon restart, a broker forgets when its log files have been
> > > > > appended to ("firstAppendTime"). Then a potentially infinite amount
> > of
> > > > time
> > > > > later, the restarted broker receives another message for the
> > particular
> > > > > (topic, partition), and starts the clock again. It will then roll
> > over
> > > > that
> > > > > log after an hour.
> > > > >
> > > > >
> > > > >
> > > >
> > >
> >
> https://svn.apache.org/repos/asf/kafka/branches/0.7/core/src/main/scala/kafka/server/KafkaConfig.scalasays
> > > > > :
> > > > >
> > > > >   /* the maximum time before a new log segment is rolled out */

 
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Adam Talaat 2013-04-26, 17:33
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Dan Frankowski 2013-04-27, 21:37
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Dan Frankowski 2013-05-02, 21:23
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Jun Rao 2013-05-03, 15:58
NEW: Monitor These Apps!
elasticsearch, apache solr, apache hbase, hadoop, redis, casssandra, amazon cloudwatch, mysql, memcached, apache kafka, apache zookeeper, apache storm, ubuntu, centOS, red hat, debian, puppet labs, java, senseiDB