http://git-wip-us.apache.org/repos/asf/flink-web/blob/b68e1f48/content/faq.html ---------------------------------------------------------------------- diff --git a/content/faq.html b/content/faq.html index ca6df08..03a0a65 100644 --- a/content/faq.html +++ b/content/faq.html @@ -180,41 +180,41 @@ under the License. <div class="page-toc"> <ul id="markdown-toc"> - <li><a href="#general">General</a> <ul> - <li><a href="#is-flink-a-hadoop-project">Is Flink a Hadoop Project?</a></li> - <li><a href="#do-i-have-to-install-apache-hadoop-to-use-flink">Do I have to install Apache Hadoop to use Flink?</a></li> + <li><a href="#general" id="markdown-toc-general">General</a> <ul> + <li><a href="#is-flink-a-hadoop-project" id="markdown-toc-is-flink-a-hadoop-project">Is Flink a Hadoop Project?</a></li> + <li><a href="#do-i-have-to-install-apache-hadoop-to-use-flink" id="markdown-toc-do-i-have-to-install-apache-hadoop-to-use-flink">Do I have to install Apache Hadoop to use Flink?</a></li> </ul> </li> - <li><a href="#usage">Usage</a> <ul> - <li><a href="#how-do-i-assess-the-progress-of-a-flink-program">How do I assess the progress of a Flink program?</a></li> - <li><a href="#how-can-i-figure-out-why-a-program-failed">How can I figure out why a program failed?</a></li> - <li><a href="#how-do-i-debug-flink-programs">How do I debug Flink programs?</a></li> - <li><a href="#what-is-the-parallelism-how-do-i-set-it">What is the parallelism? How do I set it?</a></li> + <li><a href="#usage" id="markdown-toc-usage">Usage</a> <ul> + <li><a href="#how-do-i-assess-the-progress-of-a-flink-program" id="markdown-toc-how-do-i-assess-the-progress-of-a-flink-program">How do I assess the progress of a Flink program?</a></li> + <li><a href="#how-can-i-figure-out-why-a-program-failed" id="markdown-toc-how-can-i-figure-out-why-a-program-failed">How can I figure out why a program failed?</a></li> + <li><a href="#how-do-i-debug-flink-programs" id="markdown-toc-how-do-i-debug-flink-programs">How do I debug Flink programs?</a></li> + <li><a href="#what-is-the-parallelism-how-do-i-set-it" id="markdown-toc-what-is-the-parallelism-how-do-i-set-it">What is the parallelism? How do I set it?</a></li> </ul> </li> - <li><a href="#errors">Errors</a> <ul> - <li><a href="#why-am-i-getting-a-nonserializableexception-">Why am I getting a âNonSerializableExceptionâ ?</a></li> - <li><a href="#in-scala-api-i-get-an-error-about-implicit-values-and-evidence-parameters">In Scala API, I get an error about implicit values and evidence parameters</a></li> - <li><a href="#i-get-an-error-message-saying-that-not-enough-buffers-are-available-how-do-i-fix-this">I get an error message saying that not enough buffers are available. How do I fix this?</a></li> - <li><a href="#my-job-fails-early-with-a-javaioeofexception-what-could-be-the-cause">My job fails early with a java.io.EOFException. What could be the cause?</a></li> - <li><a href="#my-job-fails-with-various-exceptions-from-the-hdfshadoop-code-what-can-i-do">My job fails with various exceptions from the HDFS/Hadoop code. What can I do?</a></li> - <li><a href="#in-eclipse-i-get-compilation-errors-in-the-scala-projects">In Eclipse, I get compilation errors in the Scala projects</a></li> - <li><a href="#my-program-does-not-compute-the-correct-result-why-are-my-custom-key-types">My program does not compute the correct result. Why are my custom key types</a></li> - <li><a href="#i-get-a-javalanginstantiationexception-for-my-data-type-what-is-wrong">I get a java.lang.InstantiationException for my data type, what is wrong?</a></li> - <li><a href="#i-cant-stop-flink-with-the-provided-stop-scripts-what-can-i-do">I canât stop Flink with the provided stop-scripts. What can I do?</a></li> - <li><a href="#i-got-an-outofmemoryexception-what-can-i-do">I got an OutOfMemoryException. What can I do?</a></li> - <li><a href="#why-do-the-taskmanager-log-files-become-so-huge">Why do the TaskManager log files become so huge?</a></li> - <li><a href="#the-slot-allocated-for-my-task-manager-has-been-released-what-should-i-do">The slot allocated for my task manager has been released. What should I do?</a></li> + <li><a href="#errors" id="markdown-toc-errors">Errors</a> <ul> + <li><a href="#why-am-i-getting-a-nonserializableexception-" id="markdown-toc-why-am-i-getting-a-nonserializableexception-">Why am I getting a âNonSerializableExceptionâ ?</a></li> + <li><a href="#in-scala-api-i-get-an-error-about-implicit-values-and-evidence-parameters" id="markdown-toc-in-scala-api-i-get-an-error-about-implicit-values-and-evidence-parameters">In Scala API, I get an error about implicit values and evidence parameters</a></li> + <li><a href="#i-get-an-error-message-saying-that-not-enough-buffers-are-available-how-do-i-fix-this" id="markdown-toc-i-get-an-error-message-saying-that-not-enough-buffers-are-available-how-do-i-fix-this">I get an error message saying that not enough buffers are available. How do I fix this?</a></li> + <li><a href="#my-job-fails-early-with-a-javaioeofexception-what-could-be-the-cause" id="markdown-toc-my-job-fails-early-with-a-javaioeofexception-what-could-be-the-cause">My job fails early with a java.io.EOFException. What could be the cause?</a></li> + <li><a href="#my-job-fails-with-various-exceptions-from-the-hdfshadoop-code-what-can-i-do" id="markdown-toc-my-job-fails-with-various-exceptions-from-the-hdfshadoop-code-what-can-i-do">My job fails with various exceptions from the HDFS/Hadoop code. What can I do?</a></li> + <li><a href="#in-eclipse-i-get-compilation-errors-in-the-scala-projects" id="markdown-toc-in-eclipse-i-get-compilation-errors-in-the-scala-projects">In Eclipse, I get compilation errors in the Scala projects</a></li> + <li><a href="#my-program-does-not-compute-the-correct-result-why-are-my-custom-key-types" id="markdown-toc-my-program-does-not-compute-the-correct-result-why-are-my-custom-key-types">My program does not compute the correct result. Why are my custom key types</a></li> + <li><a href="#i-get-a-javalanginstantiationexception-for-my-data-type-what-is-wrong" id="markdown-toc-i-get-a-javalanginstantiationexception-for-my-data-type-what-is-wrong">I get a java.lang.InstantiationException for my data type, what is wrong?</a></li> + <li><a href="#i-cant-stop-flink-with-the-provided-stop-scripts-what-can-i-do" id="markdown-toc-i-cant-stop-flink-with-the-provided-stop-scripts-what-can-i-do">I canât stop Flink with the provided stop-scripts. What can I do?</a></li> + <li><a href="#i-got-an-outofmemoryexception-what-can-i-do" id="markdown-toc-i-got-an-outofmemoryexception-what-can-i-do">I got an OutOfMemoryException. What can I do?</a></li> + <li><a href="#why-do-the-taskmanager-log-files-become-so-huge" id="markdown-toc-why-do-the-taskmanager-log-files-become-so-huge">Why do the TaskManager log files become so huge?</a></li> + <li><a href="#the-slot-allocated-for-my-task-manager-has-been-released-what-should-i-do" id="markdown-toc-the-slot-allocated-for-my-task-manager-has-been-released-what-should-i-do">The slot allocated for my task manager has been released. What should I do?</a></li> </ul> </li> - <li><a href="#yarn-deployment">YARN Deployment</a> <ul> - <li><a href="#the-yarn-session-runs-only-for-a-few-seconds">The YARN session runs only for a few seconds</a></li> - <li><a href="#the-yarn-session-crashes-with-a-hdfs-permission-exception-during-startup">The YARN session crashes with a HDFS permission exception during startup</a></li> + <li><a href="#yarn-deployment" id="markdown-toc-yarn-deployment">YARN Deployment</a> <ul> + <li><a href="#the-yarn-session-runs-only-for-a-few-seconds" id="markdown-toc-the-yarn-session-runs-only-for-a-few-seconds">The YARN session runs only for a few seconds</a></li> + <li><a href="#the-yarn-session-crashes-with-a-hdfs-permission-exception-during-startup" id="markdown-toc-the-yarn-session-crashes-with-a-hdfs-permission-exception-during-startup">The YARN session crashes with a HDFS permission exception during startup</a></li> </ul> </li> - <li><a href="#features">Features</a> <ul> - <li><a href="#what-kind-of-fault-tolerance-does-flink-provide">What kind of fault-tolerance does Flink provide?</a></li> - <li><a href="#are-hadoop-like-utilities-such-as-counters-and-the-distributedcache-supported">Are Hadoop-like utilities, such as Counters and the DistributedCache supported?</a></li> + <li><a href="#features" id="markdown-toc-features">Features</a> <ul> + <li><a href="#what-kind-of-fault-tolerance-does-flink-provide" id="markdown-toc-what-kind-of-fault-tolerance-does-flink-provide">What kind of fault-tolerance does Flink provide?</a></li> + <li><a href="#are-hadoop-like-utilities-such-as-counters-and-the-distributedcache-supported" id="markdown-toc-are-hadoop-like-utilities-such-as-counters-and-the-distributedcache-supported">Are Hadoop-like utilities, such as Counters and the DistributedCache supported?</a></li> </ul> </li> </ul> @@ -444,7 +444,7 @@ cluster.sh</code>). You can kill their processes on Linux/Mac as follows:</p> <ul> <li>Determine the process id (pid) of the JobManager / TaskManager process. You can use the <code>jps</code> command on Linux(if you have OpenJDK installed) or command -<code>ps -ef | grep java</code> to find all Java processes. </li> +<code>ps -ef | grep java</code> to find all Java processes.</li> <li>Kill the process with <code>kill -9 <pid></code>, where <code>pid</code> is the process id of the affected JobManager or TaskManager process.</li> </ul>
http://git-wip-us.apache.org/repos/asf/flink-web/blob/b68e1f48/content/how-to-contribute.html ---------------------------------------------------------------------- diff --git a/content/how-to-contribute.html b/content/how-to-contribute.html index 6701d75..9b681e9 100644 --- a/content/how-to-contribute.html +++ b/content/how-to-contribute.html @@ -161,17 +161,17 @@ <div class="page-toc"> <ul id="markdown-toc"> - <li><a href="#ask-questions">Ask questions!</a></li> - <li><a href="#file-a-bug-report">File a bug report</a></li> - <li><a href="#propose-an-improvement-or-a-new-feature">Propose an improvement or a new feature</a></li> - <li><a href="#help-others-and-join-the-discussions">Help others and join the discussions</a></li> - <li><a href="#test-a-release-candidate">Test a release candidate</a></li> - <li><a href="#contribute-code">Contribute code</a></li> - <li><a href="#contribute-documentation">Contribute documentation</a></li> - <li><a href="#improve-the-website">Improve the website</a></li> - <li><a href="#more-ways-to-contribute">More ways to contributeâ¦</a></li> - <li><a href="#submit-a-contributor-license-agreement">Submit a Contributor License Agreement</a></li> - <li><a href="#how-to-become-a-committer">How to become a committer</a></li> + <li><a href="#ask-questions" id="markdown-toc-ask-questions">Ask questions!</a></li> + <li><a href="#file-a-bug-report" id="markdown-toc-file-a-bug-report">File a bug report</a></li> + <li><a href="#propose-an-improvement-or-a-new-feature" id="markdown-toc-propose-an-improvement-or-a-new-feature">Propose an improvement or a new feature</a></li> + <li><a href="#help-others-and-join-the-discussions" id="markdown-toc-help-others-and-join-the-discussions">Help others and join the discussions</a></li> + <li><a href="#test-a-release-candidate" id="markdown-toc-test-a-release-candidate">Test a release candidate</a></li> + <li><a href="#contribute-code" id="markdown-toc-contribute-code">Contribute code</a></li> + <li><a href="#contribute-documentation" id="markdown-toc-contribute-documentation">Contribute documentation</a></li> + <li><a href="#improve-the-website" id="markdown-toc-improve-the-website">Improve the website</a></li> + <li><a href="#more-ways-to-contribute" id="markdown-toc-more-ways-to-contribute">More ways to contributeâ¦</a></li> + <li><a href="#submit-a-contributor-license-agreement" id="markdown-toc-submit-a-contributor-license-agreement">Submit a Contributor License Agreement</a></li> + <li><a href="#how-to-become-a-committer" id="markdown-toc-how-to-become-a-committer">How to become a committer</a></li> </ul> </div> @@ -198,7 +198,7 @@ <li>It allow for constructive discussions that might arise around this issue.</li> </ul> -<p>Detailed information is also required, if you plan to contribute the improvement or feature you proposed yourself. Please read the <a href="/contribute-code.html">Contribute code</a> guide in this case as well. </p> +<p>Detailed information is also required, if you plan to contribute the improvement or feature you proposed yourself. Please read the <a href="/contribute-code.html">Contribute code</a> guide in this case as well.</p> <hr /> @@ -225,7 +225,7 @@ <li>Going back to step 1 if the release candidate had issues otherwise we publish the release.</li> </ol> -<p>Our wiki contains a page that summarizes the <a href="https://cwiki.apache.org/confluence/display/FLINK/Releasing";>test procedure for a release</a>. Release testing is a big effort if done by a small group of people but can be easily scaled out to more people. The Flink community encourages everybody to participate in the testing of a release candidate. By testing a release candidate, you can ensure that the next Flink release is working properly for your setup and help to improve the quality of releases. </p> +<p>Our wiki contains a page that summarizes the <a href="https://cwiki.apache.org/confluence/display/FLINK/Releasing";>test procedure for a release</a>. Release testing is a big effort if done by a small group of people but can be easily scaled out to more people. The Flink community encourages everybody to participate in the testing of a release candidate. By testing a release candidate, you can ensure that the next Flink release is working properly for your setup and help to improve the quality of releases.</p> <hr /> @@ -239,7 +239,7 @@ <h3 class="no_toc" id="looking-for-an-issue-to-work-on">Looking for an issue to work on?</h3> -<p>We maintain a list of all known bugs, proposed improvements and suggested features in <a href="https://issues.apache.org/jira/browse/FLINK/?selectedTab=com.atlassian.jira.jira-projects-plugin:issues-panel";>Flinkâs JIRA</a>. Issues that we believe are good tasks for new contributors are tagged with a special âstarterâ tag. Those tasks are supposed to be rather easy to solve and will help you to become familiar with the project and the contribution process. </p> +<p>We maintain a list of all known bugs, proposed improvements and suggested features in <a href="https://issues.apache.org/jira/browse/FLINK/?selectedTab=com.atlassian.jira.jira-projects-plugin:issues-panel";>Flinkâs JIRA</a>. Issues that we believe are good tasks for new contributors are tagged with a special âstarterâ tag. Those tasks are supposed to be rather easy to solve and will help you to become familiar with the project and the contribution process.</p> <p>Please have a look at the list of <a href="https://issues.apache.org/jira/issues/?jql=project%20%3D%20FLINK%20AND%20resolution%20%3D%20Unresolved%20AND%20labels%20%3D%20starter%20ORDER%20BY%20priority%20DESC";>starter issues</a>, if you are looking for an issue to work on. You can of course also choose <a href="https://issues.apache.org/jira/issues/?jql=project%20%3D%20FLINK%20AND%20resolution%20%3D%20Unresolved%20ORDER%20BY%20priority%20DESC";>any other issue</a> to work on. Feel free to ask questions about issues that you would be interested in working on.</p> @@ -304,7 +304,7 @@ <h2 id="how-to-become-a-committer">How to become a committer</h2> -<p>Committers are community members that have write access to the projectâs repositories, i.e., they can modify the code, documentation, and website by themselves and also accept other contributions. </p> +<p>Committers are community members that have write access to the projectâs repositories, i.e., they can modify the code, documentation, and website by themselves and also accept other contributions.</p> <p>There is no strict protocol for becoming a committer. Candidates for new committers are typically people that are active contributors and community members.</p> @@ -312,7 +312,7 @@ <p>Of course, contributing code and documentation to the project is important as well. A good way to start is contributing improvements, new features, or bug fixes. You need to show that you take responsibility for the code that you contribute, add tests and documentation, and help maintaining it.</p> -<p>Candidates for new committers are suggested by current committers or PMC members, and voted upon by the PMC. </p> +<p>Candidates for new committers are suggested by current committers or PMC members, and voted upon by the PMC.</p> <p>If you would like to become a committer, you should engage with the community and start contributing to Apache Flink in any of the above ways. You might also want to talk to other committers and ask for their advice and guidance.</p> http://git-wip-us.apache.org/repos/asf/flink-web/blob/b68e1f48/content/improve-website.html ---------------------------------------------------------------------- diff --git a/content/improve-website.html b/content/improve-website.html index e80fefb..e35a199 100644 --- a/content/improve-website.html +++ b/content/improve-website.html @@ -169,11 +169,11 @@ <div class="page-toc"> <ul id="markdown-toc"> - <li><a href="#obtain-the-website-sources">Obtain the website sources</a></li> - <li><a href="#directory-structure-and-files">Directory structure and files</a></li> - <li><a href="#update-or-extend-the-documentation">Update or extend the documentation</a></li> - <li><a href="#submit-your-contribution">Submit your contribution</a></li> - <li><a href="#committer-section">Committer section</a></li> + <li><a href="#obtain-the-website-sources" id="markdown-toc-obtain-the-website-sources">Obtain the website sources</a></li> + <li><a href="#directory-structure-and-files" id="markdown-toc-directory-structure-and-files">Directory structure and files</a></li> + <li><a href="#update-or-extend-the-documentation" id="markdown-toc-update-or-extend-the-documentation">Update or extend the documentation</a></li> + <li><a href="#submit-your-contribution" id="markdown-toc-submit-your-contribution">Submit your contribution</a></li> + <li><a href="#committer-section" id="markdown-toc-committer-section">Committer section</a></li> </ul> </div> http://git-wip-us.apache.org/repos/asf/flink-web/blob/b68e1f48/content/material.html ---------------------------------------------------------------------- diff --git a/content/material.html b/content/material.html index 6c4f4cf..5dc923c 100644 --- a/content/material.html +++ b/content/material.html @@ -159,14 +159,14 @@ <div class="page-toc"> <ul id="markdown-toc"> - <li><a href="#apache-flink-logos">Apache Flink Logos</a> <ul> - <li><a href="#portable-network-graphics-png">Portable Network Graphics (PNG)</a></li> - <li><a href="#scalable-vector-graphics-svg">Scalable Vector Graphics (SVG)</a></li> - <li><a href="#photoshop-psd">Photoshop (PSD)</a></li> + <li><a href="#apache-flink-logos" id="markdown-toc-apache-flink-logos">Apache Flink Logos</a> <ul> + <li><a href="#portable-network-graphics-png" id="markdown-toc-portable-network-graphics-png">Portable Network Graphics (PNG)</a></li> + <li><a href="#scalable-vector-graphics-svg" id="markdown-toc-scalable-vector-graphics-svg">Scalable Vector Graphics (SVG)</a></li> + <li><a href="#photoshop-psd" id="markdown-toc-photoshop-psd">Photoshop (PSD)</a></li> </ul> </li> - <li><a href="#color-scheme">Color Scheme</a></li> - <li><a href="#slides">Slides</a></li> + <li><a href="#color-scheme" id="markdown-toc-color-scheme">Color Scheme</a></li> + <li><a href="#slides" id="markdown-toc-slides">Slides</a></li> </ul> </div> http://git-wip-us.apache.org/repos/asf/flink-web/blob/b68e1f48/content/news/2014/01/13/stratosphere-release-0.4.html ---------------------------------------------------------------------- diff --git a/content/news/2014/01/13/stratosphere-release-0.4.html b/content/news/2014/01/13/stratosphere-release-0.4.html index f6e28bd..028f019 100644 --- a/content/news/2014/01/13/stratosphere-release-0.4.html +++ b/content/news/2014/01/13/stratosphere-release-0.4.html @@ -159,7 +159,7 @@ <article> <p>13 Jan 2014</p> -<p>We are pleased to announce that version 0.4 of the Stratosphere system has been released. </p> +<p>We are pleased to announce that version 0.4 of the Stratosphere system has been released.</p> <p>Our team has been working hard during the last few months to create an improved and stable Stratosphere version. The new version comes with many new features, usability and performance improvements in all levels, including a new Scala API for the concise specification of programs, a Pregel-like API, support for Yarn clusters, and major performance improvements. The system features now first-class support for iterative programs and thus covers traditional analytical use cases as well as data mining and graph processing use cases with great performance.</p> @@ -187,7 +187,7 @@ Follow <a href="/docs/0.4/setup/yarn.html">our guide</a> on how to start a Strat <p>The high-level language Meteor now natively serializes JSON trees for greater performance and offers additional operators and file formats. We greatly empowered the user to write crispier scripts by adding second-order functions, multi-output operators, and other syntactical sugar. For developers of Meteor packages, the API is much more comprehensive and allows to define custom data types that can be easily embedded in JSON trees through ad-hoc byte code generation.</p> <h3 id="spargel-pregel-inspired-graph-processing">Spargel: Pregel Inspired Graph Processing</h3> -<p>Spargel is a vertex-centric API similar to the interface proposed in Googleâs Pregel paper and implemented in Apache Giraph. Spargel is implemented in 500 lines of code (including comments) on top of Stratosphereâs delta iterations feature. This confirms the flexibility of Stratosphereâs architecture. </p> +<p>Spargel is a vertex-centric API similar to the interface proposed in Googleâs Pregel paper and implemented in Apache Giraph. Spargel is implemented in 500 lines of code (including comments) on top of Stratosphereâs delta iterations feature. This confirms the flexibility of Stratosphereâs architecture.</p> <h3 id="web-frontend">Web Frontend</h3> <p>Using the new web frontend, you can monitor the progress of Stratosphere jobs. For finished jobs, the frontend shows a breakdown of the execution times for each operator. The webclient also visualizes the execution strategies chosen by the optimizer.</p> @@ -215,7 +215,7 @@ Follow <a href="/docs/0.4/setup/yarn.html">our guide</a> on how to start a Strat </ul> <h3 id="download-and-get-started-with-stratosphere-v04">Download and get started with Stratosphere v0.4</h3> -<p>There are several options for getting started with Stratosphere. </p> +<p>There are several options for getting started with Stratosphere.</p> <ul> <li>Download it on the <a href="/downloads">download page</a></li> http://git-wip-us.apache.org/repos/asf/flink-web/blob/b68e1f48/content/news/2014/02/18/amazon-elastic-mapreduce-cloud-yarn.html ---------------------------------------------------------------------- diff --git a/content/news/2014/02/18/amazon-elastic-mapreduce-cloud-yarn.html b/content/news/2014/02/18/amazon-elastic-mapreduce-cloud-yarn.html index b30d553..eca3ce2 100644 --- a/content/news/2014/02/18/amazon-elastic-mapreduce-cloud-yarn.html +++ b/content/news/2014/02/18/amazon-elastic-mapreduce-cloud-yarn.html @@ -229,7 +229,7 @@ ssh had...@ec2-54-213-61-105.us-west-2.compute.amazonaws.com -i ~/Downloads/work-laptop.pem</code></pre></div> <p>(Windows users have to follow <a href="http://docs.aws.amazon.com/ElasticMapReduce/latest/DeveloperGuide/emr-connect-master-node-ssh.html";>these instructions</a> to SSH into the machine running the master.) </br></br> -Once connected to the master, download and start Stratosphere for YARN: </p> +Once connected to the master, download and start Stratosphere for YARN:</p> <ul> <li>Download and extract Stratosphere-YARN</li> @@ -252,11 +252,11 @@ The arguments have the following meaning </ul> </ul> -<p>Once the output has changed from </p> +<p>Once the output has changed from</p> <div class="highlight"><pre><code class="language-bash" data-lang="bash">JobManager is now running on N/A:6123</code></pre></div> -<p>to </p> +<p>to</p> <div class="highlight"><pre><code class="language-bash" data-lang="bash">JobManager is now running on ip-172-31-13-68.us-west-2.compute.internal:6123</code></pre></div> http://git-wip-us.apache.org/repos/asf/flink-web/blob/b68e1f48/content/news/2014/11/04/release-0.7.0.html ---------------------------------------------------------------------- diff --git a/content/news/2014/11/04/release-0.7.0.html b/content/news/2014/11/04/release-0.7.0.html index 33825e7..9d97cb6 100644 --- a/content/news/2014/11/04/release-0.7.0.html +++ b/content/news/2014/11/04/release-0.7.0.html @@ -179,7 +179,7 @@ <p><strong>Record API deprecated:</strong> The (old) Stratosphere Record API has been marked as deprecated and is planned for removal in the 0.9.0 release.</p> -<p><strong>BLOB service:</strong> This release contains a new service to distribute jar files and other binary data among the JobManager, TaskManagers and the client. </p> +<p><strong>BLOB service:</strong> This release contains a new service to distribute jar files and other binary data among the JobManager, TaskManagers and the client.</p> <p><strong>Intermediate data sets:</strong> A major rewrite of the system internals introduces intermediate data sets as first class citizens. The internal state machine that tracks the distributed tasks has also been completely rewritten for scalability. While this is not visible as a user-facing feature yet, it is the foundation for several upcoming exciting features.</p> http://git-wip-us.apache.org/repos/asf/flink-web/blob/b68e1f48/content/news/2014/11/18/hadoop-compatibility.html ---------------------------------------------------------------------- diff --git a/content/news/2014/11/18/hadoop-compatibility.html b/content/news/2014/11/18/hadoop-compatibility.html index 0db27fd..067d456 100644 --- a/content/news/2014/11/18/hadoop-compatibility.html +++ b/content/news/2014/11/18/hadoop-compatibility.html @@ -167,7 +167,7 @@ <img src="/img/blog/hcompat-logos.png" style="width:30%;margin:15px" /> </center> -<p>To close this gap, Flink provides a Hadoop Compatibility package to wrap functions implemented against Hadoopâs MapReduce interfaces and embed them in Flink programs. This package was developed as part of a <a href="https://developers.google.com/open-source/soc/";>Google Summer of Code</a> 2014 project. </p> +<p>To close this gap, Flink provides a Hadoop Compatibility package to wrap functions implemented against Hadoopâs MapReduce interfaces and embed them in Flink programs. This package was developed as part of a <a href="https://developers.google.com/open-source/soc/";>Google Summer of Code</a> 2014 project.</p> <p>With the Hadoop Compatibility package, you can reuse all your Hadoop</p> @@ -180,7 +180,7 @@ <p>in Flink programs without changing a line of code. Moreover, Flink also natively supports all Hadoop data types (<code>Writables</code> and <code>WritableComparable</code>).</p> -<p>The following code snippet shows a simple Flink WordCount program that solely uses Hadoop data types, InputFormat, OutputFormat, Mapper, and Reducer functions. </p> +<p>The following code snippet shows a simple Flink WordCount program that solely uses Hadoop data types, InputFormat, OutputFormat, Mapper, and Reducer functions.</p> <div class="highlight"><pre><code class="language-java"><span class="c1">// Definition of Hadoop Mapper function</span> <span class="kd">public</span> <span class="kd">class</span> <span class="nc">Tokenizer</span> <span class="kd">implements</span> <span class="n">Mapper</span><span class="o"><</span><span class="n">LongWritable</span><span class="o">,</span> <span class="n">Text</span><span class="o">,</span> <span class="n">Text</span><span class="o">,</span> <span class="n">LongWritable</span><span class="o">></span> <span class="o">{</span> <span class="o">...</span> <span class="o">}</span> http://git-wip-us.apache.org/repos/asf/flink-web/blob/b68e1f48/content/news/2015/01/21/release-0.8.html ---------------------------------------------------------------------- diff --git a/content/news/2015/01/21/release-0.8.html b/content/news/2015/01/21/release-0.8.html index abcd1dc..ee5c54a 100644 --- a/content/news/2015/01/21/release-0.8.html +++ b/content/news/2015/01/21/release-0.8.html @@ -210,7 +210,7 @@ <li>Stefan Bunk</li> <li>Paris Carbone</li> <li>Ufuk Celebi</li> - <li>Nils Engelbach </li> + <li>Nils Engelbach</li> <li>Stephan Ewen</li> <li>Gyula Fora</li> <li>Gabor Hermann</li> http://git-wip-us.apache.org/repos/asf/flink-web/blob/b68e1f48/content/news/2015/02/04/january-in-flink.html ---------------------------------------------------------------------- diff --git a/content/news/2015/02/04/january-in-flink.html b/content/news/2015/02/04/january-in-flink.html index fb784a9..96b73f6 100644 --- a/content/news/2015/02/04/january-in-flink.html +++ b/content/news/2015/02/04/january-in-flink.html @@ -191,7 +191,7 @@ <h3 id="using-off-heap-memoryhttpsgithubcomapacheflinkpull290"><a href="https://github.com/apache/flink/pull/290";>Using off-heap memory</a></h3> -<p>This pull request enables Flink to use off-heap memory for its internal memory uses (sort, hash, caching of intermediate data sets). </p> +<p>This pull request enables Flink to use off-heap memory for its internal memory uses (sort, hash, caching of intermediate data sets).</p> <h3 id="gelly-flinks-graph-apihttpsgithubcomapacheflinkpull335"><a href="https://github.com/apache/flink/pull/335";>Gelly, Flinkâs Graph API</a></h3> http://git-wip-us.apache.org/repos/asf/flink-web/blob/b68e1f48/content/news/2015/02/09/streaming-example.html ---------------------------------------------------------------------- diff --git a/content/news/2015/02/09/streaming-example.html b/content/news/2015/02/09/streaming-example.html index e60e63e..3b3fd55 100644 --- a/content/news/2015/02/09/streaming-example.html +++ b/content/news/2015/02/09/streaming-example.html @@ -195,7 +195,7 @@ found <a href="https://github.com/mbalassi/flink/blob/stockprices/flink-staging/ <li>Read a socket stream of stock prices</li> <li>Parse the text in the stream to create a stream of <code>StockPrice</code> objects</li> <li>Add four other sources tagged with the stock symbol.</li> - <li>Finally, merge the streams to create a unified stream. </li> + <li>Finally, merge the streams to create a unified stream.</li> </ol> <p><img alt="Reading from multiple inputs" src="/img/blog/blog_multi_input.png" width="70%" class="img-responsive center-block" /></p> @@ -667,7 +667,7 @@ number of mentions of a given stock in the Twitter stream. As both of these data streams are potentially infinite, we apply the join on a 30-second window.</p> -<p><img alt="Streaming joins" src="/img/blog/blog_stream_join.png" width="60%" class="img-responsive center-block" /> </p> +<p><img alt="Streaming joins" src="/img/blog/blog_stream_join.png" width="60%" class="img-responsive center-block" /></p> <div class="codetabs"> http://git-wip-us.apache.org/repos/asf/flink-web/blob/b68e1f48/content/news/2015/03/13/peeking-into-Apache-Flinks-Engine-Room.html ---------------------------------------------------------------------- diff --git a/content/news/2015/03/13/peeking-into-Apache-Flinks-Engine-Room.html b/content/news/2015/03/13/peeking-into-Apache-Flinks-Engine-Room.html index 93566d6..5f4c5af 100644 --- a/content/news/2015/03/13/peeking-into-Apache-Flinks-Engine-Room.html +++ b/content/news/2015/03/13/peeking-into-Apache-Flinks-Engine-Room.html @@ -166,7 +166,7 @@ <p>In this blog post, we cut through Apache Flinkâs layered architecture and take a look at its internals with a focus on how it handles joins. Specifically, I will</p> <ul> - <li>show how easy it is to join data sets using Flinkâs fluent APIs, </li> + <li>show how easy it is to join data sets using Flinkâs fluent APIs,</li> <li>discuss basic distributed join strategies, Flinkâs join implementations, and its memory management,</li> <li>talk about Flinkâs optimizer that automatically chooses join strategies,</li> <li>show some performance numbers for joining data sets of different sizes, and finally</li> @@ -177,7 +177,7 @@ <h3 id="how-do-i-join-with-flink">How do I join with Flink?</h3> -<p>Flink provides fluent APIs in Java and Scala to write data flow programs. Flinkâs APIs are centered around parallel data collections which are called data sets. data sets are processed by applying Transformations that compute new data sets. Flinkâs transformations include Map and Reduce as known from MapReduce <a href="http://research.google.com/archive/mapreduce.html";>[1]</a> but also operators for joining, co-grouping, and iterative processing. The documentation gives an overview of all available transformations <a href="http://ci.apache.org/projects/flink/flink-docs-release-0.8/dataset_transformations.html";>[2]</a>. </p> +<p>Flink provides fluent APIs in Java and Scala to write data flow programs. Flinkâs APIs are centered around parallel data collections which are called data sets. data sets are processed by applying Transformations that compute new data sets. Flinkâs transformations include Map and Reduce as known from MapReduce <a href="http://research.google.com/archive/mapreduce.html";>[1]</a> but also operators for joining, co-grouping, and iterative processing. The documentation gives an overview of all available transformations <a href="http://ci.apache.org/projects/flink/flink-docs-release-0.8/dataset_transformations.html";>[2]</a>.</p> <p>Joining two Scala case class data sets is very easy as the following example shows:</p> @@ -214,7 +214,7 @@ <ol> <li>The data of both inputs is distributed across all parallel instances that participate in the join and</li> - <li>each parallel instance performs a standard stand-alone join algorithm on its local partition of the overall data. </li> + <li>each parallel instance performs a standard stand-alone join algorithm on its local partition of the overall data.</li> </ol> <p>The distribution of data across parallel instances must ensure that each valid join pair can be locally built by exactly one instance. For both steps, there are multiple valid strategies that can be independently picked and which are favorable in different situations. In Flink terminology, the first phase is called Ship Strategy and the second phase Local Strategy. In the following I will describe Flinkâs ship and local strategies to join two data sets <em>R</em> and <em>S</em>.</p> @@ -233,7 +233,7 @@ <img src="/img/blog/joins-repartition.png" style="width:90%;margin:15px" /> </center> -<p>The Broadcast-Forward strategy sends one complete data set (R) to each parallel instance that holds a partition of the other data set (S), i.e., each parallel instance receives the full data set R. Data set S remains local and is not shipped at all. The cost of the BF strategy depends on the size of R and the number of parallel instances it is shipped to. The size of S does not matter because S is not moved. The figure below illustrates how both ship strategies work. </p> +<p>The Broadcast-Forward strategy sends one complete data set (R) to each parallel instance that holds a partition of the other data set (S), i.e., each parallel instance receives the full data set R. Data set S remains local and is not shipped at all. The cost of the BF strategy depends on the size of R and the number of parallel instances it is shipped to. The size of S does not matter because S is not moved. The figure below illustrates how both ship strategies work.</p> <center> <img src="/img/blog/joins-broadcast.png" style="width:90%;margin:15px" /> @@ -242,7 +242,7 @@ <p>The Repartition-Repartition and Broadcast-Forward ship strategies establish suitable data distributions to execute a distributed join. Depending on the operations that are applied before the join, one or even both inputs of a join are already distributed in a suitable way across parallel instances. In this case, Flink will reuse such distributions and only ship one or no input at all.</p> <h4 id="flinks-memory-management">Flinkâs Memory Management</h4> -<p>Before delving into the details of Flinkâs local join algorithms, I will briefly discuss Flinkâs internal memory management. Data processing algorithms such as joining, grouping, and sorting need to hold portions of their input data in memory. While such algorithms perform best if there is enough memory available to hold all data, it is crucial to gracefully handle situations where the data size exceeds memory. Such situations are especially tricky in JVM-based systems such as Flink because the system needs to reliably recognize that it is short on memory. Failure to detect such situations can result in an <code>OutOfMemoryException</code> and kill the JVM. </p> +<p>Before delving into the details of Flinkâs local join algorithms, I will briefly discuss Flinkâs internal memory management. Data processing algorithms such as joining, grouping, and sorting need to hold portions of their input data in memory. While such algorithms perform best if there is enough memory available to hold all data, it is crucial to gracefully handle situations where the data size exceeds memory. Such situations are especially tricky in JVM-based systems such as Flink because the system needs to reliably recognize that it is short on memory. Failure to detect such situations can result in an <code>OutOfMemoryException</code> and kill the JVM.</p> <p>Flink handles this challenge by actively managing its memory. When a worker node (TaskManager) is started, it allocates a fixed portion (70% by default) of the JVMâs heap memory that is available after initialization as 32KB byte arrays. These byte arrays are distributed as working memory to all algorithms that need to hold significant portions of data in memory. The algorithms receive their input data as Java data objects and serialize them into their working memory.</p> @@ -259,7 +259,7 @@ <p>After the data has been distributed across all parallel join instances using either a Repartition-Repartition or Broadcast-Forward ship strategy, each instance runs a local join algorithm to join the elements of its local partition. Flinkâs runtime features two common join strategies to perform these local joins:</p> <ul> - <li>the <em>Sort-Merge-Join</em> strategy (SM) and </li> + <li>the <em>Sort-Merge-Join</em> strategy (SM) and</li> <li>the <em>Hybrid-Hash-Join</em> strategy (HH).</li> </ul> @@ -304,13 +304,13 @@ <ul> <li>1GB : 1000GB</li> <li>10GB : 1000GB</li> - <li>100GB : 1000GB </li> + <li>100GB : 1000GB</li> <li>1000GB : 1000GB</li> </ul> <p>The Broadcast-Forward strategy is only executed for up to 10GB. Building a hash table from 100GB broadcasted data in 5GB working memory would result in spilling proximately 95GB (build input) + 950GB (probe input) in each parallel thread and require more than 8TB local disk storage on each machine.</p> -<p>As in the single-core benchmark, we run 1:N joins, generate the data on-the-fly, and immediately discard the result after the join. We run the benchmark on 10 n1-highmem-8 Google Compute Engine instances. Each instance is equipped with 8 cores, 52GB RAM, 40GB of which are configured as working memory (5GB per core), and one local SSD for spilling to disk. All benchmarks are performed using the same configuration, i.e., no fine tuning for the respective data sizes is done. The programs are executed with a parallelism of 80. </p> +<p>As in the single-core benchmark, we run 1:N joins, generate the data on-the-fly, and immediately discard the result after the join. We run the benchmark on 10 n1-highmem-8 Google Compute Engine instances. Each instance is equipped with 8 cores, 52GB RAM, 40GB of which are configured as working memory (5GB per core), and one local SSD for spilling to disk. All benchmarks are performed using the same configuration, i.e., no fine tuning for the respective data sizes is done. The programs are executed with a parallelism of 80.</p> <center> <img src="/img/blog/joins-dist-perf.png" style="width:70%;margin:15px" /> @@ -327,7 +327,7 @@ <ul> <li>Flinkâs fluent Scala and Java APIs make joins and other data transformations easy as cake.</li> <li>The optimizer does the hard choices for you, but gives you control in case you know better.</li> - <li>Flinkâs join implementations perform very good in-memory and gracefully degrade when going to disk. </li> + <li>Flinkâs join implementations perform very good in-memory and gracefully degrade when going to disk.</li> <li>Due to Flinkâs robust memory management, there is no need for job- or data-specific memory tuning to avoid a nasty <code>OutOfMemoryException</code>. It just runs out-of-the-box.</li> </ul> http://git-wip-us.apache.org/repos/asf/flink-web/blob/b68e1f48/content/news/2015/05/11/Juggling-with-Bits-and-Bytes.html ---------------------------------------------------------------------- diff --git a/content/news/2015/05/11/Juggling-with-Bits-and-Bytes.html b/content/news/2015/05/11/Juggling-with-Bits-and-Bytes.html index 6c442e5..c018d89 100644 --- a/content/news/2015/05/11/Juggling-with-Bits-and-Bytes.html +++ b/content/news/2015/05/11/Juggling-with-Bits-and-Bytes.html @@ -178,7 +178,7 @@ However, this approach has a few notable drawbacks. First of all it is not trivi <img src="/img/blog/memory-mgmt.png" style="width:90%;margin:15px" /> </center> -<p>Flinkâs style of active memory management and operating on binary data has several benefits: </p> +<p>Flinkâs style of active memory management and operating on binary data has several benefits:</p> <ol> <li><strong>Memory-safe execution & efficient out-of-core algorithms.</strong> Due to the fixed amount of allocated memory segments, it is trivial to monitor remaining memory resources. In case of memory shortage, processing operators can efficiently write larger batches of memory segments to disk and later them read back. Consequently, <code>OutOfMemoryErrors</code> are effectively prevented.</li> @@ -187,13 +187,13 @@ However, this approach has a few notable drawbacks. First of all it is not trivi <li><strong>Efficient binary operations & cache sensitivity.</strong> Binary data can be efficiently compared and operated on given a suitable binary representation. Furthermore, the binary representations can put related values, as well as hash codes, keys, and pointers, adjacently into memory. This gives data structures with usually more cache efficient access patterns.</li> </ol> -<p>These properties of active memory management are very desirable in a data processing systems for large-scale data analytics but have a significant price tag attached. Active memory management and operating on binary data is not trivial to implement, i.e., using <code>java.util.HashMap</code> is much easier than implementing a spillable hash-table backed by byte arrays and a custom serialization stack. Of course Apache Flink is not the only JVM-based data processing system that operates on serialized binary data. Projects such as <a href="http://drill.apache.org/";>Apache Drill</a>, <a href="http://ignite.incubator.apache.org/";>Apache Ignite (incubating)</a> or <a href="http://projectgeode.org/";>Apache Geode (incubating)</a> apply similar techniques and it was recently announced that also <a href="http://spark.apache.org/";>Apache Spark</a> will evolve into this direction with <a href="https://databricks.com/blog/2015/04/28/project-tungsten-bringing-spark-closer-to-bare-metal.html";> Project Tungsten</a>. </p> +<p>These properties of active memory management are very desirable in a data processing systems for large-scale data analytics but have a significant price tag attached. Active memory management and operating on binary data is not trivial to implement, i.e., using <code>java.util.HashMap</code> is much easier than implementing a spillable hash-table backed by byte arrays and a custom serialization stack. Of course Apache Flink is not the only JVM-based data processing system that operates on serialized binary data. Projects such as <a href="http://drill.apache.org/";>Apache Drill</a>, <a href="http://ignite.incubator.apache.org/";>Apache Ignite (incubating)</a> or <a href="http://projectgeode.org/";>Apache Geode (incubating)</a> apply similar techniques and it was recently announced that also <a href="http://spark.apache.org/";>Apache Spark</a> will evolve into this direction with <a href="https://databricks.com/blog/2015/04/28/project-tungsten-bringing-spark-closer-to-bare-metal.html";> Project Tungsten</a>.</p> <p>In the following we discuss in detail how Flink allocates memory, de/serializes objects, and operates on binary data. We will also show some performance numbers comparing processing objects on the heap and operating on binary data.</p> <h2 id="how-does-flink-allocate-memory">How does Flink allocate memory?</h2> -<p>A Flink worker, called TaskManager, is composed of several internal components such as an actor system for coordination with the Flink master, an IOManager that takes care of spilling data to disk and reading it back, and a MemoryManager that coordinates memory usage. In the context of this blog post, the MemoryManager is of most interest. </p> +<p>A Flink worker, called TaskManager, is composed of several internal components such as an actor system for coordination with the Flink master, an IOManager that takes care of spilling data to disk and reading it back, and a MemoryManager that coordinates memory usage. In the context of this blog post, the MemoryManager is of most interest.</p> <p>The MemoryManager takes care of allocating, accounting, and distributing MemorySegments to data processing operators such as sort and join operators. A <a href="https://github.com/apache/flink/blob/release-0.9.0-milestone-1/flink-core/src/main/java/org/apache/flink/core/memory/MemorySegment.java";>MemorySegment</a> is Flinkâs distribution unit of memory and is backed by a regular Java byte array (size is 32 KB by default). A MemorySegment provides very efficient write and read access to its backed byte array using Javaâs unsafe methods. You can think of a MemorySegment as a custom-tailored version of Javaâs NIO ByteBuffer. In order to operate on multiple MemorySegments like on a larger chunk of consecutive memory, Flink uses logical views that implement Javaâs <code>java.io.DataOutput</code> and <code>java.io.DataInput</code> interfaces.</p> @@ -205,7 +205,7 @@ However, this approach has a few notable drawbacks. First of all it is not trivi <h2 id="how-does-flink-serialize-objects">How does Flink serialize objects?</h2> -<p>The Java ecosystem offers several libraries to convert objects into a binary representation and back. Common alternatives are standard Java serialization, <a href="https://github.com/EsotericSoftware/kryo";>Kryo</a>, <a href="http://avro.apache.org/";>Apache Avro</a>, <a href="http://thrift.apache.org/";>Apache Thrift</a>, or Googleâs <a href="https://github.com/google/protobuf";>Protobuf</a>. Flink includes its own custom serialization framework in order to control the binary representation of data. This is important because operating on binary data such as comparing or even manipulating binary data requires exact knowledge of the serialization layout. Further, configuring the serialization layout with respect to operations that are performed on binary data can yield a significant performance boost. Flinkâs serialization stack also leverages the fact, that the type of the objects which are going through de/serialization are exactly known before a program is executed. </p> +<p>The Java ecosystem offers several libraries to convert objects into a binary representation and back. Common alternatives are standard Java serialization, <a href="https://github.com/EsotericSoftware/kryo";>Kryo</a>, <a href="http://avro.apache.org/";>Apache Avro</a>, <a href="http://thrift.apache.org/";>Apache Thrift</a>, or Googleâs <a href="https://github.com/google/protobuf";>Protobuf</a>. Flink includes its own custom serialization framework in order to control the binary representation of data. This is important because operating on binary data such as comparing or even manipulating binary data requires exact knowledge of the serialization layout. Further, configuring the serialization layout with respect to operations that are performed on binary data can yield a significant performance boost. Flinkâs serialization stack also leverages the fact, that the type of the objects which are going through de/serialization are exactly known before a program is executed.</p> <p>Flink programs can process data represented as arbitrary Java or Scala objects. Before a program is optimized, the data types at each processing step of the programâs data flow need to be identified. For Java programs, Flink features a reflection-based type extraction component to analyze the return types of user-defined functions. Scala programs are analyzed with help of the Scala compiler. Flink represents each data type with a <a href="https://github.com/apache/flink/blob/release-0.9.0-milestone-1/flink-core/src/main/java/org/apache/flink/api/common/typeinfo/TypeInformation.java";>TypeInformation</a>. Flink has TypeInformations for several kinds of data types, including:</p> @@ -215,11 +215,11 @@ However, this approach has a few notable drawbacks. First of all it is not trivi <li>WritableTypeInfo: Any implementation of Hadoopâs Writable interface.</li> <li>TupleTypeInfo: Any Flink tuple (Tuple1 to Tuple25). Flink tuples are Java representations for fixed-length tuples with typed fields.</li> <li>CaseClassTypeInfo: Any Scala CaseClass (including Scala tuples).</li> - <li>PojoTypeInfo: Any POJO (Java or Scala), i.e., an object with all fields either being public or accessible through getters and setter that follow the common naming conventions. </li> + <li>PojoTypeInfo: Any POJO (Java or Scala), i.e., an object with all fields either being public or accessible through getters and setter that follow the common naming conventions.</li> <li>GenericTypeInfo: Any data type that cannot be identified as another type.</li> </ul> -<p>Each TypeInformation provides a serializer for the data type it represents. For example, a BasicTypeInfo returns a serializer that writes the respective primitive type, the serializer of a WritableTypeInfo delegates de/serialization to the write() and readFields() methods of the object implementing Hadoopâs Writable interface, and a GenericTypeInfo returns a serializer that delegates serialization to Kryo. Object serialization to a DataOutput which is backed by Flink MemorySegments goes automatically through Javaâs efficient unsafe operations. For data types that can be used as keys, i.e., compared and hashed, the TypeInformation provides TypeComparators. TypeComparators compare and hash objects and can - depending on the concrete data type - also efficiently compare binary representations and extract fixed-length binary key prefixes. </p> +<p>Each TypeInformation provides a serializer for the data type it represents. For example, a BasicTypeInfo returns a serializer that writes the respective primitive type, the serializer of a WritableTypeInfo delegates de/serialization to the write() and readFields() methods of the object implementing Hadoopâs Writable interface, and a GenericTypeInfo returns a serializer that delegates serialization to Kryo. Object serialization to a DataOutput which is backed by Flink MemorySegments goes automatically through Javaâs efficient unsafe operations. For data types that can be used as keys, i.e., compared and hashed, the TypeInformation provides TypeComparators. TypeComparators compare and hash objects and can - depending on the concrete data type - also efficiently compare binary representations and extract fixed-length binary key prefixes.</p> <p>Tuple, Pojo, and CaseClass types are composite types, i.e., containers for one or more possibly nested data types. As such, their serializers and comparators are also composite and delegate the serialization and comparison of their member data types to the respective serializers and comparators. The following figure illustrates the serialization of a (nested) <code>Tuple3<Integer, Double, Person></code> object where <code>Person</code> is a POJO and defined as follows:</p> @@ -232,13 +232,13 @@ However, this approach has a few notable drawbacks. First of all it is not trivi <img src="/img/blog/data-serialization.png" style="width:80%;margin:15px" /> </center> -<p>Flinkâs type system can be easily extended by providing custom TypeInformations, Serializers, and Comparators to improve the performance of serializing and comparing custom data types. </p> +<p>Flinkâs type system can be easily extended by providing custom TypeInformations, Serializers, and Comparators to improve the performance of serializing and comparing custom data types.</p> <h2 id="how-does-flink-operate-on-binary-data">How does Flink operate on binary data?</h2> <p>Similar to many other data processing APIs (including SQL), Flinkâs APIs provide transformations to group, sort, and join data sets. These transformations operate on potentially very large data sets. Relational database systems feature very efficient algorithms for these purposes since several decades including external merge-sort, merge-join, and hybrid hash-join. Flink builds on this technology, but generalizes it to handle arbitrary objects using its custom serialization and comparison stack. In the following, we show how Flink operates with binary data by the example of Flinkâs in-memory sort algorithm.</p> -<p>Flink assigns a memory budget to its data processing operators. Upon initialization, a sort algorithm requests its memory budget from the MemoryManager and receives a corresponding set of MemorySegments. The set of MemorySegments becomes the memory pool of a so-called sort buffer which collects the data that is be sorted. The following figure illustrates how data objects are serialized into the sort buffer. </p> +<p>Flink assigns a memory budget to its data processing operators. Upon initialization, a sort algorithm requests its memory budget from the MemoryManager and receives a corresponding set of MemorySegments. The set of MemorySegments becomes the memory pool of a so-called sort buffer which collects the data that is be sorted. The following figure illustrates how data objects are serialized into the sort buffer.</p> <center> <img src="/img/blog/sorting-binary-data-1.png" style="width:90%;margin:15px" /> @@ -251,7 +251,7 @@ The following figure shows how two objects are compared.</p> <img src="/img/blog/sorting-binary-data-2.png" style="width:80%;margin:15px" /> </center> -<p>The sort buffer compares two elements by comparing their binary fix-length sort keys. The comparison is successful if either done on a full key (not a prefix key) or if the binary prefix keys are not equal. If the prefix keys are equal (or the sort key data type does not provide a binary prefix key), the sort buffer follows the pointers to the actual object data, deserializes both objects and compares the objects. Depending on the result of the comparison, the sort algorithm decides whether to swap the compared elements or not. The sort buffer swaps two elements by moving their fix-length keys and pointers. The actual data is not moved. Once the sort algorithm finishes, the pointers in the sort buffer are correctly ordered. The following figure shows how the sorted data is returned from the sort buffer. </p> +<p>The sort buffer compares two elements by comparing their binary fix-length sort keys. The comparison is successful if either done on a full key (not a prefix key) or if the binary prefix keys are not equal. If the prefix keys are equal (or the sort key data type does not provide a binary prefix key), the sort buffer follows the pointers to the actual object data, deserializes both objects and compares the objects. Depending on the result of the comparison, the sort algorithm decides whether to swap the compared elements or not. The sort buffer swaps two elements by moving their fix-length keys and pointers. The actual data is not moved. Once the sort algorithm finishes, the pointers in the sort buffer are correctly ordered. The following figure shows how the sorted data is returned from the sort buffer.</p> <center> <img src="/img/blog/sorting-binary-data-3.png" style="width:80%;margin:15px" /> @@ -269,7 +269,7 @@ The following figure shows how two objects are compared.</p> <li><strong>Kryo-serialized.</strong> The tuple fields are serialized into a sort buffer of 600 MB size using Kryo serialization and sorted without binary sort keys. This means that each pair-wise comparison requires two object to be deserialized.</li> </ol> -<p>All sort methods are implemented using a single thread. The reported times are averaged over ten runs. After each run, we call <code>System.gc()</code> to request a garbage collection run which does not go into measured execution time. The following figure shows the time to store the input data in memory, sort it, and read it back as objects. </p> +<p>All sort methods are implemented using a single thread. The reported times are averaged over ten runs. After each run, we call <code>System.gc()</code> to request a garbage collection run which does not go into measured execution time. The following figure shows the time to store the input data in memory, sort it, and read it back as objects.</p> <center> <img src="/img/blog/sort-benchmark.png" style="width:90%;margin:15px" /> @@ -327,13 +327,13 @@ The following figure shows how two objects are compared.</p> <p><br /></p> -<p>To summarize, the experiments verify the previously stated benefits of operating on binary data. </p> +<p>To summarize, the experiments verify the previously stated benefits of operating on binary data.</p> <h2 id="were-not-done-yet">Weâre not done yet!</h2> -<p>Apache Flink features quite a bit of advanced techniques to safely and efficiently process huge amounts of data with limited memory resources. However, there are a few points that could make Flink even more efficient. The Flink community is working on moving the managed memory to off-heap memory. This will allow for smaller JVMs, lower garbage collection overhead, and also easier system configuration. With Flinkâs Table API, the semantics of all operations such as aggregations and projections are known (in contrast to black-box user-defined functions). Hence we can generate code for Table API operations that directly operates on binary data. Further improvements include serialization layouts which are tailored towards the operations that are applied on the binary data and code generation for serializers and comparators. </p> +<p>Apache Flink features quite a bit of advanced techniques to safely and efficiently process huge amounts of data with limited memory resources. However, there are a few points that could make Flink even more efficient. The Flink community is working on moving the managed memory to off-heap memory. This will allow for smaller JVMs, lower garbage collection overhead, and also easier system configuration. With Flinkâs Table API, the semantics of all operations such as aggregations and projections are known (in contrast to black-box user-defined functions). Hence we can generate code for Table API operations that directly operates on binary data. Further improvements include serialization layouts which are tailored towards the operations that are applied on the binary data and code generation for serializers and comparators.</p> -<p>The groundwork (and a lot more) for operating on binary data is done but there is still some room for making Flink even better and faster. If you are crazy about performance and like to juggle with lot of bits and bytes, join the Flink community! </p> +<p>The groundwork (and a lot more) for operating on binary data is done but there is still some room for making Flink even better and faster. If you are crazy about performance and like to juggle with lot of bits and bytes, join the Flink community!</p> <h2 id="tldr-give-me-three-things-to-remember">TL;DR; Give me three things to remember!</h2> http://git-wip-us.apache.org/repos/asf/flink-web/blob/b68e1f48/content/news/2015/05/14/Community-update-April.html ---------------------------------------------------------------------- diff --git a/content/news/2015/05/14/Community-update-April.html b/content/news/2015/05/14/Community-update-April.html index 2e0210d..1523a02 100644 --- a/content/news/2015/05/14/Community-update-April.html +++ b/content/news/2015/05/14/Community-update-April.html @@ -159,7 +159,7 @@ <article> <p>14 May 2015 by Kostas Tzoumas (<a href="https://twitter.com/kostas_tzoumas";>@kostas_tzoumas</a>)</p> -<p>April was an packed month for Apache Flink. </p> +<p>April was an packed month for Apache Flink.</p> <h2 id="flink-090-milestone1-release">Flink 0.9.0-milestone1 release</h2> @@ -175,7 +175,7 @@ <h2 id="flink-on-the-web">Flink on the web</h2> -<p>Fabian Hueske gave an <a href="http://www.infoq.com/news/2015/04/hueske-apache-flink?utm_campaign=infoq_content&utm_source=infoq&utm_medium=feed&utm_term=global";>interview at InfoQ</a> on Apache Flink. </p> +<p>Fabian Hueske gave an <a href="http://www.infoq.com/news/2015/04/hueske-apache-flink?utm_campaign=infoq_content&utm_source=infoq&utm_medium=feed&utm_term=global";>interview at InfoQ</a> on Apache Flink.</p> <h2 id="upcoming-events">Upcoming events</h2> http://git-wip-us.apache.org/repos/asf/flink-web/blob/b68e1f48/content/news/2015/08/24/introducing-flink-gelly.html ---------------------------------------------------------------------- diff --git a/content/news/2015/08/24/introducing-flink-gelly.html b/content/news/2015/08/24/introducing-flink-gelly.html index 2bc2f8a..2e05a24 100644 --- a/content/news/2015/08/24/introducing-flink-gelly.html +++ b/content/news/2015/08/24/introducing-flink-gelly.html @@ -225,21 +225,21 @@ and mutations as well as neighborhood aggregations.</p> <h4 id="common-graph-metrics">Common Graph Metrics</h4> <p>These methods can be used to retrieve several graph metrics and properties, such as the number -of vertices, edges and the node degrees. </p> +of vertices, edges and the node degrees.</p> <h4 id="transformations">Transformations</h4> <p>The transformation methods enable several Graph operations, using high-level functions similar to the ones provided by the batch processing API. These transformations can be applied one after the -other, yielding a new Graph after each step, in a fashion similar to operators on DataSets: </p> +other, yielding a new Graph after each step, in a fashion similar to operators on DataSets:</p> <div class="highlight"><pre><code class="language-java"><span class="n">inputGraph</span><span class="o">.</span><span class="na">getUndirected</span><span class="o">().</span><span class="na">mapEdges</span><span class="o">(</span><span class="k">new</span> <span class="nf">CustomEdgeMapper</span><span class="o">());</span></code></pre></div> <p>Transformations can be applied on:</p> <ol> - <li><strong>Vertices</strong>: <code>mapVertices</code>, <code>joinWithVertices</code>, <code>filterOnVertices</code>, <code>addVertex</code>, ⦠</li> - <li><strong>Edges</strong>: <code>mapEdges</code>, <code>filterOnEdges</code>, <code>removeEdge</code>, ⦠</li> - <li><strong>Triplets</strong> (source vertex, target vertex, edge): <code>getTriplets</code> </li> + <li><strong>Vertices</strong>: <code>mapVertices</code>, <code>joinWithVertices</code>, <code>filterOnVertices</code>, <code>addVertex</code>, â¦</li> + <li><strong>Edges</strong>: <code>mapEdges</code>, <code>filterOnEdges</code>, <code>removeEdge</code>, â¦</li> + <li><strong>Triplets</strong> (source vertex, target vertex, edge): <code>getTriplets</code></li> </ol> <h4 id="neighborhood-aggregations">Neighborhood Aggregations</h4> @@ -373,7 +373,7 @@ vertex values do not need to be recomputed during an iteration.</p> <p>Let us reconsider the Single Source Shortest Paths algorithm. In each iteration, a vertex:</p> <ol> - <li><strong>Gather</strong> retrieves distances from its neighbors summed up with the corresponding edge values; </li> + <li><strong>Gather</strong> retrieves distances from its neighbors summed up with the corresponding edge values;</li> <li><strong>Sum</strong> compares the newly obtained distances in order to extract the minimum;</li> <li><strong>Apply</strong> and finally adopts the minimum distance computed in the sum step, provided that it is lower than its current value. If a vertexâs value does not change during @@ -432,7 +432,7 @@ plays that each song has. We then filter out the list of songs the users do not playlist. Then we compute the top songs per user (i.e. the songs a user listened to the most). Finally, as a separate use-case on the same data set, we create a user-user similarity graph based on the common songs and use this resulting graph to detect communities by calling Gellyâs Label Propagation -library method. </p> +library method.</p> <p>For running the example implementation, please use the 0.10-SNAPSHOT version of Flink as a dependency. The full example code base can be found <a href="https://github.com/apache/flink/blob/master/flink-staging/flink-gelly/src/main/java/org/apache/flink/graph/example/MusicProfiles.java";>here</a>. The public data set used for testing @@ -522,10 +522,10 @@ in the figure below.</p> <p>To form the user-user graph in Flink, we will simply take the edges from the user-song graph (left-hand side of the image), group them by song-id, and then add all the users (source vertex ids) -to an ArrayList. </p> +to an ArrayList.</p> <p>We then match users who listened to the same song two by two, creating a new edge to mark their -common interest (right-hand side of the image). </p> +common interest (right-hand side of the image).</p> <p>Afterwards, we perform a <code>distinct()</code> operation to avoid creation of duplicate data. Considering that we now have the DataSet of edges which present interest, creating a graph is as @@ -564,7 +564,7 @@ formed. To do so, we first initialize each vertex with a numeric label using the the id of a vertex with the first element of the tuple, afterwards applying a map function. Finally, we call the <code>run()</code> method with the LabelPropagation library method passed as a parameter. In the end, the vertices will be updated to contain the most frequent label -among their neighbors. </p> +among their neighbors.</p> <div class="highlight"><pre><code class="language-java"><span class="c1">// detect user communities using label propagation</span> <span class="c1">// initialize each vertex with a unique numeric label</span> @@ -594,10 +594,10 @@ among their neighbors. </p> <p>Currently, Gelly matches the basic functionalities provided by most state-of-the-art graph processing systems. Our vision is to turn Gelly into more than âyet another library for running PageRank-like algorithmsâ by supporting generic iterations, implementing graph partitioning, -providing bipartite graph support and by offering numerous other features. </p> +providing bipartite graph support and by offering numerous other features.</p> <p>We are also enriching Flink Gelly with a set of operators suitable for highly skewed graphs -as well as a Graph API built on Flink Streaming. </p> +as well as a Graph API built on Flink Streaming.</p> <p>In the near future, we would like to see how Gelly can be integrated with graph visualization tools, graph database systems and sampling techniques.</p> http://git-wip-us.apache.org/repos/asf/flink-web/blob/b68e1f48/content/news/2015/09/16/off-heap-memory.html ---------------------------------------------------------------------- diff --git a/content/news/2015/09/16/off-heap-memory.html b/content/news/2015/09/16/off-heap-memory.html index 50f4016..c1b1efc 100644 --- a/content/news/2015/09/16/off-heap-memory.html +++ b/content/news/2015/09/16/off-heap-memory.html @@ -205,7 +205,7 @@ <h2 id="the-off-heap-memory-implementation">The off-heap Memory Implementation</h2> -<p>Given that all memory intensive internal algorithms are already implemented against the <code>MemorySegment</code>, our implementation to switch to off-heap memory is actually trivial. You can compare it to replacing all <code>ByteBuffer.allocate(numBytes)</code> calls with <code>ByteBuffer.allocateDirect(numBytes)</code>. In Flinkâs case it meant that we made the <code>MemorySegment</code> abstract and added the <code>HeapMemorySegment</code> and <code>OffHeapMemorySegment</code> subclasses. The <code>OffHeapMemorySegment</code> takes the off-heap memory pointer from a <code>java.nio.DirectByteBuffer</code> and implements its specialized access methods using <code>sun.misc.Unsafe</code>. We also made a few adjustments to the startup scripts and the deployment code to make sure that the JVM is permitted enough off-heap memory (direct memory, <em>-XX:MaxDirectMemorySize</em>). </p> +<p>Given that all memory intensive internal algorithms are already implemented against the <code>MemorySegment</code>, our implementation to switch to off-heap memory is actually trivial. You can compare it to replacing all <code>ByteBuffer.allocate(numBytes)</code> calls with <code>ByteBuffer.allocateDirect(numBytes)</code>. In Flinkâs case it meant that we made the <code>MemorySegment</code> abstract and added the <code>HeapMemorySegment</code> and <code>OffHeapMemorySegment</code> subclasses. The <code>OffHeapMemorySegment</code> takes the off-heap memory pointer from a <code>java.nio.DirectByteBuffer</code> and implements its specialized access methods using <code>sun.misc.Unsafe</code>. We also made a few adjustments to the startup scripts and the deployment code to make sure that the JVM is permitted enough off-heap memory (direct memory, <em>-XX:MaxDirectMemorySize</em>).</p> <p>In practice we had to go one step further, to make the implementation perform well. While the <code>ByteBuffer</code> is used in I/O code paths to compose headers and move bulk memory into place, the MemorySegment is part of the innermost loops of many algorithms (sorting, hash tables, â¦). That means that the access methods have to be as fast as possible.</p> http://git-wip-us.apache.org/repos/asf/flink-web/blob/b68e1f48/content/news/2015/11/16/release-0.10.0.html ---------------------------------------------------------------------- diff --git a/content/news/2015/11/16/release-0.10.0.html b/content/news/2015/11/16/release-0.10.0.html index 7afd6e6..1bf2ff7 100644 --- a/content/news/2015/11/16/release-0.10.0.html +++ b/content/news/2015/11/16/release-0.10.0.html @@ -161,7 +161,7 @@ <p>The Apache Flink community is pleased to announce the availability of the 0.10.0 release. The community put significant effort into improving and extending Apache Flink since the last release, focusing on data stream processing and operational features. About 80 contributors provided bug fixes, improvements, and new features such that in total more than 400 JIRA issues could be resolved.</p> -<p>For Flink 0.10.0, the focus of the community was to graduate the DataStream API from beta and to evolve Apache Flink into a production-ready stream data processor with a competitive feature set. These efforts resulted in support for event-time and out-of-order streams, exactly-once guarantees in the case of failures, a very flexible windowing mechanism, sophisticated operator state management, and a highly-available cluster operation mode. Flink 0.10.0 also brings a new monitoring dashboard with real-time system and job monitoring capabilities. Both batch and streaming modes of Flink benefit from the new high availability and improved monitoring features. Needless to say that Flink 0.10.0 includes many more features, improvements, and bug fixes. </p> +<p>For Flink 0.10.0, the focus of the community was to graduate the DataStream API from beta and to evolve Apache Flink into a production-ready stream data processor with a competitive feature set. These efforts resulted in support for event-time and out-of-order streams, exactly-once guarantees in the case of failures, a very flexible windowing mechanism, sophisticated operator state management, and a highly-available cluster operation mode. Flink 0.10.0 also brings a new monitoring dashboard with real-time system and job monitoring capabilities. Both batch and streaming modes of Flink benefit from the new high availability and improved monitoring features. Needless to say that Flink 0.10.0 includes many more features, improvements, and bug fixes.</p> <p>We encourage everyone to <a href="/downloads.html">download the release</a> and <a href="https://ci.apache.org/projects/flink/flink-docs-release-0.10/";>check out the documentation</a>. Feedback through the Flink <a href="/community.html#mailing-lists">mailing lists</a> is, as always, very welcome!</p> http://git-wip-us.apache.org/repos/asf/flink-web/blob/b68e1f48/content/news/2015/12/04/Introducing-windows.html ---------------------------------------------------------------------- diff --git a/content/news/2015/12/04/Introducing-windows.html b/content/news/2015/12/04/Introducing-windows.html index 23536b4..d246e4a 100644 --- a/content/news/2015/12/04/Introducing-windows.html +++ b/content/news/2015/12/04/Introducing-windows.html @@ -159,7 +159,7 @@ <article> <p>04 Dec 2015 by Fabian Hueske (<a href="https://twitter.com/fhueske";>@fhueske</a>)</p> -<p>The data analysis space is witnessing an evolution from batch to stream processing for many use cases. Although batch can be handled as a special case of stream processing, analyzing never-ending streaming data often requires a shift in the mindset and comes with its own terminology (for example, âwindowingâ and âat-least-onceâ/âexactly-onceâ processing). This shift and the new terminology can be quite confusing for people being new to the space of stream processing. Apache Flink is a production-ready stream processor with an easy-to-use yet very expressive API to define advanced stream analysis programs. Flinkâs API features very flexible window definitions on data streams which let it stand out among other open source stream processors. </p> +<p>The data analysis space is witnessing an evolution from batch to stream processing for many use cases. Although batch can be handled as a special case of stream processing, analyzing never-ending streaming data often requires a shift in the mindset and comes with its own terminology (for example, âwindowingâ and âat-least-onceâ/âexactly-onceâ processing). This shift and the new terminology can be quite confusing for people being new to the space of stream processing. Apache Flink is a production-ready stream processor with an easy-to-use yet very expressive API to define advanced stream analysis programs. Flinkâs API features very flexible window definitions on data streams which let it stand out among other open source stream processors.</p> <p>In this blog post, we discuss the concept of windows for stream processing, present Flinkâs built-in windows, and explain its support for custom windowing semantics.</p> @@ -222,17 +222,17 @@ <p>There is one aspect that we havenât discussed yet, namely the exact meaning of â<em>collects elements for one minute</em>â which boils down to the question, â<em>How does the stream processor interpret time?</em>â.</p> -<p>Apache Flink features three different notions of time, namely <em>processing time</em>, <em>event time</em>, and <em>ingestion time</em>. </p> +<p>Apache Flink features three different notions of time, namely <em>processing time</em>, <em>event time</em>, and <em>ingestion time</em>.</p> <ol> - <li>In <strong>processing time</strong>, windows are defined with respect to the wall clock of the machine that builds and processes a window, i.e., a one minute processing time window collects elements for exactly one minute. </li> - <li>In <strong>event time</strong>, windows are defined with respect to timestamps that are attached to each event record. This is common for many types of events, such as log entries, sensor data, etc, where the timestamp usually represents the time at which the event occurred. Event time has several benefits over processing time. First of all, it decouples the program semantics from the actual serving speed of the source and the processing performance of system. Hence you can process historic data, which is served at maximum speed, and continuously produced data with the same program. It also prevents semantically incorrect results in case of backpressure or delays due to failure recovery. Second, event time windows compute correct results, even if events arrive out-of-order of their timestamp which is common if a data stream gathers events from distributed sources. </li> + <li>In <strong>processing time</strong>, windows are defined with respect to the wall clock of the machine that builds and processes a window, i.e., a one minute processing time window collects elements for exactly one minute.</li> + <li>In <strong>event time</strong>, windows are defined with respect to timestamps that are attached to each event record. This is common for many types of events, such as log entries, sensor data, etc, where the timestamp usually represents the time at which the event occurred. Event time has several benefits over processing time. First of all, it decouples the program semantics from the actual serving speed of the source and the processing performance of system. Hence you can process historic data, which is served at maximum speed, and continuously produced data with the same program. It also prevents semantically incorrect results in case of backpressure or delays due to failure recovery. Second, event time windows compute correct results, even if events arrive out-of-order of their timestamp which is common if a data stream gathers events from distributed sources.</li> <li><strong>Ingestion time</strong> is a hybrid of processing and event time. It assigns wall clock timestamps to records as soon as they arrive in the system (at the source) and continues processing with event time semantics based on the attached timestamps.</li> </ol> <h2 id="count-windows">Count Windows</h2> -<p>Apache Flink also features count windows. A tumbling count window of 100 will collect 100 events in a window and evaluate the window when the 100th element has been added. </p> +<p>Apache Flink also features count windows. A tumbling count window of 100 will collect 100 events in a window and evaluate the window when the 100th element has been added.</p> <p>In Flinkâs DataStream API, tumbling and sliding count windows are defined as follows:</p> @@ -255,7 +255,7 @@ <h2 id="dissecting-flinks-windowing-mechanics">Dissecting Flinkâs windowing mechanics</h2> -<p>Flinkâs built-in time and count windows cover a wide range of common window use cases. However, there are of course applications that require custom windowing logic that cannot be addressed by Flinkâs built-in windows. In order to support also applications that need very specific windowing semantics, the DataStream API exposes interfaces for the internals of its windowing mechanics. These interfaces give very fine-grained control about the way that windows are built and evaluated. </p> +<p>Flinkâs built-in time and count windows cover a wide range of common window use cases. However, there are of course applications that require custom windowing logic that cannot be addressed by Flinkâs built-in windows. In order to support also applications that need very specific windowing semantics, the DataStream API exposes interfaces for the internals of its windowing mechanics. These interfaces give very fine-grained control about the way that windows are built and evaluated.</p> <p>The following figure depicts Flinkâs windowing mechanism and introduces the components being involved.</p>
