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Flume >> mail # user >> speeding up replay log


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Edwin Chiu 2013-08-08, 19:48
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Brock Noland 2013-08-09, 11:26
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Edwin Chiu 2013-08-09, 17:10
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Re: speeding up replay log
Fast replay will start only if the checkpoint files are deleted (or don't exist). If there is a checkpoint - fast replay will not start up even if the files are corrupt/unreadable. Depending on how many events are in the channel, fast replay can also fall victim to Java's GC slowdowns. That is something to think of.  

I have filed https://issues.apache.org/jira/browse/FLUME-2155 to improve certain aspects of the File Channel replay. I have some ideas though I am not entirely sure when I will get time to work on this.  
Thanks,
Hari
On Friday, August 9, 2013 at 10:10 AM, Edwin Chiu wrote:

> Thanks, Brock! I'll check out this 1.4 feature.
>
> I already have 1.3 running on production machines though, it's still preferred to keep 1.3 unless there's no way around this potentially lengthy log replay.  
>
> In my scenario, there's about 4G of files under data directory. My system has about 40G free memory. I've restarted flume with 36G max memory in flume-env, after setting fast-replay to true.
>
> The resource monitoring shows 36G is allocated to the flume process. But while replay was running, it was using about the same amount of memory as before the new max memory was set in flume-env and with fast-replay was off.  
>
> Any tips to "force" fast-replay to kick in?
>
> thanks!
>
> - e
>
>
> - Edwin
>
> On Fri, Aug 9, 2013 at 4:26 AM, Brock Noland <[EMAIL PROTECTED] (mailto:[EMAIL PROTECTED])> wrote:
> > If fast replay doesn't help then you don't have enough RAM. I'd suggest you use the new dual checkpoint feature. Note the dual and backup checkpoint configs here:
> >
> > http://flume.apache.org/FlumeUserGuide.html#file-channel
> > http://issues.apache.org/jira/browse/FLUME-1516
> >
> > Brock
> >
> > On Thu, Aug 8, 2013 at 2:48 PM, Edwin Chiu <[EMAIL PROTECTED] (mailto:[EMAIL PROTECTED])> wrote:
> > > Hi there!
> > >
> > > I'm using flume-ng 1.3.1 (Hortonworks latest production stable version as of now) on centos 6 with jdk 1.6.  
> > >
> > > I'm wondering how to speed up the replay of logs after changing file channel parameters in flume.conf -- capacity and transactionCapacity.  
> > >
> > > it takes hours for the node to catch up and able to receive and send events again.
> > >
> > > use-fast-replay = true with a ridiculous amount of max memory doesn't speed things up.  
> > >
> > > Any recommendations to avoid the down time?
> > >
> > > thanks!
> > >
> > > Ed
> >
> >
> > --
> > Apache MRUnit - Unit testing MapReduce - http://mrunit.apache.org