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From Roshan Naik <ros...@hortonworks.com>
Subject Re: Memory Channel
Date Thu, 17 Jan 2013 01:13:34 GMT
The source and sink operate on independent threads. The source pumps data
into the  (memory) channel which is basically an in memory queue.. and the
sink would drain the queue asynchronously. so depending on the speed of the
sink, the data can remain in the channel for long/short duration.
-roshan



On Wed, Jan 16, 2013 at 11:03 AM, Mohit Anchlia <mohitanchlia@gmail.com>wrote:

> Just one more question, when I write using memorychannel does that write
> immediately gets written to the sink? It may not get sync on HDFS but does
> it at least immediately gets written. I am trying to see if the events are
> held in flume's memory or not.
>
>
> On Wed, Jan 16, 2013 at 11:00 AM, Brock Noland <brock@cloudera.com> wrote:
>
>> The HDFS Sink syncs at the end of each batch or when the file rolls.
>>
>> On Wed, Jan 16, 2013 at 10:55 AM, Nitin Pawar <nitinpawar432@gmail.com>
>> wrote:
>> > you can configure it as you nee
>> > number of events
>> > rollover by time
>> > and other ways as well
>> >
>> >
>> > On Thu, Jan 17, 2013 at 12:17 AM, Mohit Anchlia <mohitanchlia@gmail.com
>> >
>> > wrote:
>> >>
>> >> Right. I was asking about sync to "sink". My sink is hdfs so does flume
>> >> sync to hdfs on every write operation?
>> >>
>> >>
>> >> On Wed, Jan 16, 2013 at 10:26 AM, Brock Noland <brock@cloudera.com>
>> wrote:
>> >>>
>> >>> Memory Channel does not write to disk and as such never syncs to disk.
>> >>> File Channel does sync to disk for each batch put on or taken off the
>> >>> channel.
>> >>>
>> >>> On Wed, Jan 16, 2013 at 10:21 AM, Mohit Anchlia <
>> mohitanchlia@gmail.com>
>> >>> wrote:
>> >>> > Thanks! What I am really trying to understand is when does flume
>> sync
>> >>> > to the
>> >>> > sink. I am not using batch events.
>> >>> >
>> >>> >
>> >>> > On Wed, Jan 16, 2013 at 9:55 AM, Hari Shreedharan
>> >>> > <hshreedharan@cloudera.com> wrote:
>> >>> >>
>> >>> >> It means that the channel can store that many events. If it
is
>> full,
>> >>> >> then
>> >>> >> the put() calls (on the source side) will start throwing
>> >>> >> ChannelException.
>> >>> >> The put call will block only for keep-alive number of seconds,
>> after
>> >>> >> which
>> >>> >> it will throw.
>> >>> >>
>> >>> >>
>> >>> >> Hari
>> >>> >>
>> >>> >> --
>> >>> >> Hari Shreedharan
>> >>> >>
>> >>> >> On Wednesday, January 16, 2013 at 9:46 AM, Mohit Anchlia wrote:
>> >>> >>
>> >>> >> Could someone help me understand capacity attribute of
>> memoryChannel?
>> >>> >> Does
>> >>> >> it mean that memoryChannel flushes to sink only when this capacity
>> is
>> >>> >> reached or does it mean that it's the max events stored in
memory
>> and
>> >>> >> call
>> >>> >> blocks until everything else gets freed?
>> >>> >>
>> >>> >>
>> >>> >> http://flume.apache.org/FlumeUserGuide.html#memory-channel
>> >>> >>
>> >>> >>
>> >>> >>
>> >>> >
>> >>>
>> >>>
>> >>>
>> >>> --
>> >>> Apache MRUnit - Unit testing MapReduce -
>> >>> http://incubator.apache.org/mrunit/
>> >>
>> >>
>> >
>> >
>> >
>> > --
>> > Nitin Pawar
>>
>>
>>
>> --
>> Apache MRUnit - Unit testing MapReduce -
>> http://incubator.apache.org/mrunit/
>>
>
>

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