April 30, 2014

Spark on fire

Spark is on the rise, to an even greater degree than I thought last month.

*Yes, my fingerprints are showing again.

The most official description of what Spark now contains is probably the “Spark ecosystem” diagram from Databricks. However, at the time of this writing it is slightly out of date, as per some email from Databricks CEO Ion Stoica (quoted with permission):

… but if I were to redraw it, SparkSQL will replace Shark, and Shark will eventually become a thin layer above SparkSQL and below BlinkDB.

With this change, all the modules on top of Spark (i.e., SparkStreaming, SparkSQL, GraphX, and MLlib) are part of the Spark distribution. You can think of these modules as libraries that come with Spark.

In an unfortunate non-development, Tachyon is not (yet?) part of Spark, and so it is hard for a Spark job’s data to be shared with other jobs (Spark or otherwise) or processes. That said:

A couple of Spark machine learning stories are very cool, in that they involve intra-day retraining of models. The better-known one is Yahoo’s, which in a prototype built in 120 lines of code trains a new model for recommendation of each candidate top-page news story. When I challenged that anecdote, Ion told me about his own former company Conviva, which retrains models every minute to decide which particular source of streaming video each client system will be connected to.

I am generally skeptical of immature SQL efforts, and SparkSQL is no exception. That said, it seems to be going in sensible directions, which should be welcome to those folks who used or were planning to use Shark anyway.

And finally, there’s no public news as to what Databricks’ own business is. I think that’s a bit silly, but in fairness:


15 Responses to “Spark on fire”

  1. Norbert GC on April 30th, 2014 11:13 am

    Perhaps a completion, or an add-on to this welcome presentation… SparkSQL as Streaming option. This could hit direct competitors like StreamSQL and others.

  2. Patrick McFadin on May 1st, 2014 10:33 am

    More evidence of the demise of MapReduce is the recent announcement (APR-25-2014) from Apache Mahout. They will be no longer adding MR algorithms to the project as a move to “modern data processing systems”


  3. Steve Wooledge on May 1st, 2014 4:11 pm

    There is a lot of excitement in Apache Spark and here at MapR we are fully supporting it (together with Databricks) in our distribution. There are a lot of benefits with faster development and in-memory execution where optimization techniques maximize data locality across multiple iterations. We co-hosted a webinar (http://bit.ly/1rJXRna) with Databricks 2 days ago which is a great primer on the use cases and had over 50 great questions (e.g., differences between Spark Streaming and Storm).

    Re:“replacement for Hadoop MapReduce”, we take a balanced view in that Hadoop MapReduce has been tried and true in production at 1000’s of companies. MapR has many customers executing 10’s of 1000’s of jobs on with this framework. Our focus is to support broad support for multiple execution engines based on customer choice and complementary benefits of each approach. The Hadoop community is thriving with innovation, so giving customers more choice and backward compatibility (http://bit.ly/1lORVIM) across releases of different projects is important. Over time, Hadoop MR jobs may be moved to Spark jobs, but it will be a measured, “enterprise” approach.

    That said, MapR is “all in” on Apache Spark and—as you pointed out—are the only commercial Hadoop distribution that supports the whole Spark stack. More details on our blog (http://bit.ly/1ktzUxB).

  4. Curt Monash on May 1st, 2014 7:30 pm

    Specifically, Patrick’s link says new Mahout additions will be over Spark, at least if you want to run them in parallel. But old routines will still be supported.

    Thanks for the find!

  5. Shane Curcuru on May 2nd, 2014 8:11 am

    So when will the “most official description of what Spark now contains” be hosted on the actual Apache Spark project pages at http://spark.apache.org, rather than on a vendor’s site?

    A key part of the success is the permissively licensed code and the independent governance of the Apache Spark project itself. While we certainly appreciate all the IP various vendors have donated (either directly, or through their employee committers) to the ASF, it would be nice to see a little more credit to the independent Apache Spark PMC and their committers as a group.


  6. David Gruzman on May 3rd, 2014 6:21 am

    There is one thing which prevents me from designating Spark to be Hadoop map-reduce replacement: throughput. Where the advantage in throughput will come from?
    During read from HDFS Spark re-use Hadoop input formats, shuffling also do not looks superior to the Hadoop’s implementation.
    Without advantage in throughput I think Spark will take iterative and interactive jobs, but heavy batch processing will be left in Hadoop MR.

  7. Curt Monash on May 3rd, 2014 6:37 am

    Hi David!

    One thing you may be forgetting — Spark’s advantages in programmability. It has a lot more primitives than Tez, which in turn has somewhat more than classical MapReduce.

    But if you’re saying that many existing processes that run well on MR will continue to do so for quite a while, I wouldn’t argue with that.

  8. Notes and comments, May 6, 2014 | DBMS 2 : DataBase Management System Services on May 6th, 2014 9:46 am

    […] claim that Spark will replace Hadoop MapReduce got much Twitter attention — including some high-profile endorsements — and also some […]

  9. David Gruzman on May 14th, 2014 10:36 am

    During Spark benchmark I have found that indeed shuffle performance of Spark are inferior to Hadoop MapReduce. If we take enough data to disregard startup overhead, Hive group by is faster then the same group by implemented in Spark.
    We did our best to avoid most obvious performance pitfalls – used Kryo serialization for spark, and made Hadoop to utilize all available CPU by giving enough memory to Yarn.
    I am curious is it “by design” or it is possible to tune Spark to perform better in such cases.

  10. Reynold Xin on May 15th, 2014 2:23 am

    Hi David,

    Spark committer here. Thanks for the feedback. The goal of the Spark project definitely includes making it perform well in interactive, iterative, and high throughput batch jobs. Even for on-disk data, Spark typically outperforms Hadoop MapReduce in real workloads where multiple stages of MRs are required, because of fast scheduling (as you pointed out) and the ability to understand DAGs of tasks. There are also some advanced features such as data partitioning that applications can exploit that simply don’t exist in MapReduce or equivalent frameworks.

    Some of our own benchmarks as well as workloads reported by the community do include high intensity shuffles, and Spark performs quite favorably. That said, as Spark becomes more popular and is exposed to a wider variety of workloads, we do find room for improvement. In particular, both Databricks and the Spark community at large have plans to improve shuffle, including general optimizations as well as making it more pluggable to exploit characteristics of specific hardware or setup. The design of Spark makes it easy to implement many of these optimizations.

    Meantime, please reach out if you need help tuning Spark.

  11. Brian Husted on May 15th, 2014 1:04 pm


    You mentioned a benchmark with Spark. Can you elaborate on what benchmarking tool you used? We have been primarily using YCSB, but that is not integrated with the Spark API.


  12. David Gruzman on May 18th, 2014 4:24 am

    Hi Brian,
    We didn’t use any special tools. We just took several jobs we have in production with hadoop and implemented them in Spark. In this particular example it was job that boils down to “group by”


  13. Cloudera: Impala’s it for interactive SQL on Hadoop, but everything else will move to Spark — Tech News and Analysis on July 3rd, 2014 8:46 pm

    […] that time, Databricks CEO Ion Stoica told database industry analyst Curt Monash the same, although he also mentioned plans to continue developing an interactive engine called […]

  14. Cloudera: Impala’s it for interactive SQL on Hadoop; everything else will move to Spark — Tech News and Analysis on July 3rd, 2014 8:47 pm

    […] that time, Databricks CEO Ion Stoica told database industry analyst Curt Monash the same, although he also mentioned plans to continue developing an interactive engine called […]

  15. The potential significance of Cloudera Kudu | DBMS 2 : DataBase Management System Services on September 28th, 2015 3:54 am

    […] human real time. Predictive models now often get rescored on every click. Sometimes, they even get retrained at short intervals. And while data reduction in the sense of “event extraction from high-volume streams” […]

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