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From Samit Sasan <sasansa...@gmail.com>
Subject Re: ACK performance hit & Loggly abandoning Storm
Date Tue, 08 Apr 2014 12:53:47 GMT
There were a few points in the blog which either were interesting or i
totally missed the point.


   - It was mentioned that they were using without ACK turned on. So in
   that case how would it be ensured that all the tuples were successfully
   processed by all the bolts.
   - ACKing along with max tuple pending has another very important role of
   limiting congestion in the stream. Max tuple pending value will define how
   many tuples could be active in the topology. So one way of handling this
   would be to increase max tuple pending.(if you are sure your cluster/nodes
   can handle all that data).
   - Another possible experiment is to try using trident, which in turn
   will batch the log lines, leading to pipelining of batches and greater
   throughput.

-Samit



On Mon, Apr 7, 2014 at 3:50 AM, Benjamin Black <b@b3k.us> wrote:

> There is also no indication they are configuring Kafka such that it won't
> lose data in the event of a broker failure:
> http://aphyr.com/posts/293-call-me-maybe-kafka
> http://blog.empathybox.com/post/62279088548/a-few-notes-on-kafka-and-jepsen
>
> The performance hit to Kafka is similar to Storm when you enable similar
> acks:
>
>
> https://mail-archives.apache.org/mod_mbox/kafka-users/201402.mbox/%3C26ba2b6a63f54fe39b343fc673f2162c@BY2PR03MB239.namprd03.prod.outlook.com%3E
>
> "Your best result shows close to a factor of 2 difference btw ack=-1 and
> ack=1, which is actually reasonable.
>
>
> Thanks,
> Jun"
>
>
>
> On Sun, Apr 6, 2014 at 2:59 PM, Jason Jackson <jasonjckn@gmail.com> wrote:
>
>> It would of been far more useful if they measured the systems in terms of
>> dollars, as each system makes different tradeoffs. Certainly when you
>> enable acking you may become bottlenecked on CPU at that point instead of
>> being bottlenecked on disk/kafka. So one thing you can do is move to
>> hardware with higher class CPUs to solve the bottleneck. The system they
>> built is persisting intermediary queues between components in a topology.
>> So while this will reduce CPU load by not needing an acking system, you
>> will need more disks as potentially any of the intermediately queues can
>> start to fill up now, you need to reserve capacity for worst case scenario.
>> Potentially in terms of dollars the tradeoff to use more disks has
>> marginally better total cost.
>>
>>
>>
>>
>> On Fri, Apr 4, 2014 at 6:55 PM, Benjamin Black <b@b3k.us> wrote:
>>
>>> No part of the post made any sense to me. There is a significant
>>> performance hit when moving to reliable operation in any system and Storm
>>> is clearly doing a good job if a custom built solution can only manage 25%
>>> more throughput.
>>>
>>>
>>> On Fri, Apr 4, 2014 at 4:10 PM, Neelesh <neeleshs@gmail.com> wrote:
>>>
>>>> Its an interesting read. The blog is vague on some details - with ACK
>>>> on, the throughput was 80K/s. With their custom solution its 100K/s.
>>>> Assuming they were both deployed on similar hardware (I do not know , the
>>>> blog does not confirm either way), the difference is not something that
>>>> warrants a custom framework to me. Obviously its working better for Loggly.
>>>>
>>>>
>>>> On Fri, Apr 4, 2014 at 8:26 AM, Otis Gospodnetic <
>>>> otis.gospodnetic@gmail.com> wrote:
>>>>
>>>>> Hi,
>>>>>
>>>>> Apparently Loggly decided to ditch Storm when they got hit by the 2.5x
>>>>> performance degradation factor after turning on ACKing:
>>>>> https://www.loggly.com/what-we-learned-about-scaling-with-apache-storm/
>>>>>
>>>>> How does one minimize this performance hit?
>>>>> Or maybe newer versions of Storm perform better with ACK? (Loggly
>>>>> tested 0.82, they say)
>>>>>
>>>>> Thanks,
>>>>> Otis
>>>>> --
>>>>> Performance Monitoring * Log Analytics * Search Analytics
>>>>> Solr & Elasticsearch Support * http://sematext.com/
>>>>>
>>>>>
>>>>
>>>
>>
>

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