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| <h1 class="entry-title">Apache Kudu (incubating) Weekly Update May 16, 2016</h1> |
| <p class="meta">Posted 16 May 2016 by Todd Lipcon</p> |
| </header> |
| <div class="entry-content"> |
| <p>Welcome to the ninth edition of the Kudu Weekly Update. This weekly blog post |
| covers ongoing development and news in the Apache Kudu (incubating) project.</p> |
| |
| <!--more--> |
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| <p>If you find this post useful, please let us know by emailing the |
| <a href="mailto:user@kudu.incubator.apache.org">kudu-user mailing list</a> or |
| tweeting at <a href="https://twitter.com/ApacheKudu">@ApacheKudu</a>. Similarly, if you’re |
| aware of some Kudu news we missed, let us know so we can cover it in |
| a future post.</p> |
| |
| <h2 id="development-discussions-and-code-in-progress">Development discussions and code in progress</h2> |
| |
| <ul> |
| <li> |
| <p>Development and code reviews continued on Sameer Abhyankar’s patch which |
| adds support for pushing down <a href="http://gerrit.cloudera.org:8080/#/c/2986/">‘IN’ predicates</a> |
| to the Kudu tablet servers.</p> |
| </li> |
| <li> |
| <p>Todd Lipcon and Binglin Chang have been continuing to work on improving throughput |
| for a high throughput random-read use case. Initial profiling indicated that the |
| RPC system was a bottleneck, and patches have started to land which improve |
| the throughput:</p> |
| |
| <p>The largest bottleneck was in the queue which transfers RPC calls from the |
| libev “reactor” threads which perform network IO to the “worker” threads |
| which service the actual requests. Binglin borrowed some ideas from Facebook’s |
| <a href="https://github.com/facebook/folly">folly</a> library, and implemented an |
| <a href="http://gerrit.cloudera.org:8080/#/c/2938/">improved queue</a> |
| which reduces context switches and lock contention while also |
| improving CPU cache locality of the worker threads.</p> |
| |
| <p>Todd identified that the hash function used to map connections to reactor |
| threads was poor, resulting in uneven load distribution across cores. |
| A <a href="http://gerrit.cloudera.org:8080/#/c/2939/">simple patch to change the hashcode implementation</a> |
| improved the distribution substantially.</p> |
| |
| <p>With just these patches, an RPC stress benchmark was improved from about 202K RPCs/second |
| to 768K RPCs/second on a 24-core machine. Further improvements are in flight |
| and under review this week.</p> |
| </li> |
| <li> |
| <p>Zhen Zhang is continuing to focus on adding more visibility into |
| performance and resource usage by adding the ability to propagate various |
| per-operation metrics from the server side back to the client. His latest patch |
| under review <a href="http://gerrit.cloudera.org:8080/#/c/3013/">exposes scanner cache hit rate metrics</a> |
| to the client.</p> |
| </li> |
| <li> |
| <p>Todd Lipcon and Sarah Jelinek continue to make progress on the |
| implementation of a persistent-memory backed block cache. |
| This week a <a href="http://gerrit.cloudera.org:8080/#/c/2957/">substantial refactor to the block cache interface</a> |
| was committed in preparation for the <a href="http://gerrit.cloudera.org:8080/#/c/2593/">NVM cache itself</a>.</p> |
| </li> |
| <li> |
| <p>Congratulations to Will Berkeley, a new contributor who has been |
| contributing small fixes and improvements such as |
| <a href="http://gerrit.cloudera.org:8080/#/c/3022/">exposing table partitioning information in the master web UI</a>. |
| Thanks, Will!</p> |
| </li> |
| <li> |
| <p>David Alves has been continuing to make progress towards his implementation of |
| the <a href="http://gerrit.cloudera.org:8080/#/c/2642/">Replay Cache</a>. |
| This week, he refactored and cleaned up much of the client code involving |
| error handling and retrying write operations, in preparation to inserting |
| unique identifiers for these and other operations.</p> |
| </li> |
| <li> |
| <p>Chris George has continued to work on the Spark DataSource implementation. |
| In particular, work is progressing on support for <a href="http://gerrit.cloudera.org:8080/#/c/2992/">inserting and updating |
| rows via Spark</a>.</p> |
| </li> |
| <li> |
| <p>Todd Lipcon and Mike Percy both committed improvements which will help speed up |
| startup. Measurements on a cluster where each node stores a few TB of data |
| showed a 3x improvement in startup time.</p> |
| </li> |
| </ul> |
| |
| <h2 id="upcoming-talks-and-meetups">Upcoming talks and meetups</h2> |
| |
| <ul> |
| <li>Mladen Kovacevi will be presenting Kudu at the |
| <a href="http://www.meetup.com/Big-Data-Montreal/events/230879277/?eventId=230879277">Big Data Montreal</a> |
| meetup.</li> |
| </ul> |
| |
| </div> |
| </article> |
| |
| |
| </div> |
| <div class="col-lg-3 recent-posts"> |
| <h3>Recent posts</h3> |
| <ul> |
| |
| <li> <a href="/2016/07/25/asf-graduation.html">The Apache Software Foundation Announces Apache® Kudu™ as a Top-Level Project</a> </li> |
| |
| <li> <a href="/2016/07/18/weekly-update.html">Apache Kudu (incubating) Weekly Update July 18, 2016</a> </li> |
| |
| <li> <a href="/2016/07/11/weekly-update.html">Apache Kudu (incubating) Weekly Update July 11, 2016</a> </li> |
| |
| <li> <a href="/2016/07/01/apache-kudu-0-9-1-released.html">Apache Kudu (incubating) 0.9.1 released</a> </li> |
| |
| <li> <a href="/2016/06/27/weekly-update.html">Apache Kudu (incubating) Weekly Update June 27, 2016</a> </li> |
| |
| <li> <a href="/2016/06/24/multi-master-1-0-0.html">Master fault tolerance in Kudu 1.0</a> </li> |
| |
| <li> <a href="/2016/06/21/weekly-update.html">Apache Kudu (incubating) Weekly Update June 21, 2016</a> </li> |
| |
| <li> <a href="/2016/06/17/raft-consensus-single-node.html">Using Raft Consensus on a Single Node</a> </li> |
| |
| <li> <a href="/2016/06/13/weekly-update.html">Apache Kudu (incubating) Weekly Update June 13, 2016</a> </li> |
| |
| <li> <a href="/2016/06/10/apache-kudu-0-9-0-released.html">Apache Kudu (incubating) 0.9.0 released</a> </li> |
| |
| <li> <a href="/2016/06/06/weekly-update.html">Apache Kudu (incubating) Weekly Update June 6, 2016</a> </li> |
| |
| <li> <a href="/2016/06/02/no-default-partitioning.html">Default Partitioning Changes Coming in Kudu 0.9</a> </li> |
| |
| <li> <a href="/2016/06/01/weekly-update.html">Apache Kudu (incubating) Weekly Update June 1, 2016</a> </li> |
| |
| <li> <a href="/2016/05/23/weekly-update.html">Apache Kudu (incubating) Weekly Update May 23, 2016</a> </li> |
| |
| <li> <a href="/2016/05/16/weekly-update.html">Apache Kudu (incubating) Weekly Update May 16, 2016</a> </li> |
| |
| </ul> |
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