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From Arvind Prabhakar <arv...@streamsets.com>
Subject Re: Notification support from flume?
Date Mon, 08 Dec 2014 06:12:06 GMT
Flume is not suited for file transfers as such. With that, please see my
comments below:

- support for variable transaction size that could be set by the source or
> interceptor
>

The transactions are already variable sized. The only configuration that
applies on top is the maximum size of a transaction. How is this different
from what you are proposing?



>  - SpoolDir to support creation of one transaction per file
>

If the file is large, you would run out of heap space quickly. Also, how do
you recover from intermittent failures?


>  - File and Memory channels to support spawning a process on transaction
> successful commit. Such process can be a bash script, but that would be
> implemented in plug-able class


You may be better off using something like an Oozie action to trigger a job
when the dataset is complete.

Regards,
Arvind







On Sun, Dec 7, 2014 at 12:55 PM, Ahmed Vila <avila@devlogic.eu> wrote:

> Hi group,
>
> Manohar's requirements sound valid. Guess there are other cases such
> "completion notification" could come in handy.
>
> Thus, I would propose these distinct features that would make this
> possible via configuration:
>  - support for variable transaction size that could be set by the source
> or interceptor
>  - SpoolDir to support creation of one transaction per file
>  - File and Memory channels to support spawning a process on transaction
> successful commit. Such process can be a bash script, but that would be
> implemented in plug-able class
>
> The one thing I'm not sure about until I look at the code, if HDFSSink
> will write flush cache to the HDFS once it encounters no more events in a
> transaction.
>
> What do you guys think ?
>
>
> On Sat, Dec 6, 2014 at 7:31 AM, Manohar CS <Manohar.CS@itcinfotech.com>
> wrote:
>
>>  Thanks Hari for your response.
>>
>>
>>  My requirement goes like this -
>>
>>
>>  1) There are bunch of files coming in at regular intervals (hourly or
>> daily) in my spoolDir
>>
>> 2) I wan tthem to be moved into HDFS via HDFS sink using reg-ex like
>> /target/%Y-%M%D so each day file gets into different destination HDFS
>>
>> 3) Now once this flume completes copying files , I want to kick off my MR
>> job.
>>
>>
>>  Thanks,
>>
>> Manohar
>>  ------------------------------
>> *From:* Hari Shreedharan <hshreedharan@cloudera.com>
>> *Sent:* Saturday, December 6, 2014 7:16 AM
>> *To:* user@flume.apache.org
>> *Cc:* user@flume.apache.org
>> *Subject:* Re: Notification support from flume?
>>
>>  Looking at .COMPLETED is not an indication that the data has been
>> written out to HDFS. As of now, unfortunately there is no way to tag an
>> event as coming from a specific file. I can’t think of a way to do this in
>> a fool-proof way off the top of my mind. What is your use-case, there might
>> be another way to do the same thing?
>>
>> Thanks,
>> Hari
>>
>>
>>  On Fri, Dec 5, 2014 at 4:19 AM, Manohar CS <Manohar.CS@itcinfotech.com>
>> wrote:
>>
>>>  Hi All,
>>>
>>>
>>>
>>> I wanted to know if there is a way of notification mechanism or some way
>>> of finding out if flume has finished transfer of certain file from spoolDir
>>> to HDFS sink? We know by looking at .COMPLETED files in spoolDir we can
>>> assume its completed but wanted to know if there is more reliable way of
>>> call back mechanism ?
>>>
>>>
>>>
>>>
>>>
>>> Thanks,
>>>
>>> Manohar.
>>>
>>>
>>>
>>>
>>> Please consider the environment before printing this e-mail
>>>
>>>
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>>
>>
>>
>>
>> Please consider the environment before printing this e-mail
>>
>>
>> Disclaimer: This  communication  is  for the exclusive use of the intended recipient(s)
and  shall  not attach any liability on the originator or ITC Infotech India Ltd./its  Holding
company/ its Subsidiaries/ its Group Companies. If you are the addressee, the contents of
this e-mail are intended for your use only and it shall  not be forwarded to any third party,
without first obtaining written authorization from the originator or ITC Infotech India Ltd./
its Holding company/its  Subsidiaries/ its Group Companies. It may contain information which
is confidential and legally privileged and the same shall not be used or dealt with  by any
 third  party  in  any manner whatsoever without the specific consent  of  ITC  Infotech India
Ltd./ its Holding company/ its Subsidiaries/ its Group Companies.
>>
>
>
>
> --
>
> Best regards,
> Ahmed Vila | Senior software developer
> DevLogic | Sarajevo | Bosnia and Herzegovina
>
> Office : +387 33 942 123
> Mobile: +387 62 139 348
>
> Website: www.devlogic.eu
> E-mail   : avila@devlogic.eu
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