<!DOCTYPE html><html lang="en"><head><meta charSet="utf-8"/><meta http-equiv="X-UA-Compatible" content="IE=edge"/><title>Simulator Mode · Apache Heron</title><meta name="viewport" content="width=device-width"/><meta name="generator" content="Docusaurus"/><meta name="description" content="&lt;!--"/><meta name="docsearch:version" content="0.20.5-incubating"/><meta name="docsearch:language" content="en"/><meta property="og:title" content="Simulator Mode · Apache Heron"/><meta property="og:type" content="website"/><meta property="og:url" content="https://heron.apache.org/"/><meta property="og:description" content="&lt;!--"/><meta property="og:image" content="https://heron.apache.org/img/undraw_online.svg"/><meta name="twitter:card" content="summary"/><meta name="twitter:image" content="https://heron.apache.org/img/undraw_tweetstorm.svg"/><link rel="shortcut icon" href="/img/favicon-32x32.png"/><link rel="stylesheet" href="//cdnjs.cloudflare.com/ajax/libs/highlight.js/9.12.0/styles/default.min.css"/><link rel="alternate" type="application/atom+xml" href="https://heron.apache.org/blog/atom.xml" title="Apache Heron Blog ATOM Feed"/><link rel="alternate" type="application/rss+xml" href="https://heron.apache.org/blog/feed.xml" title="Apache Heron Blog RSS Feed"/><script>
              (function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
              (i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
              m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
              })(window,document,'script','https://www.google-analytics.com/analytics.js','ga');

              ga('create', 'UA-198017384-1', 'auto');
              ga('send', 'pageview');
            </script><script type="text/javascript" src="https://buttons.github.io/buttons.js"></script><script type="text/javascript" src="/js/custom.js"></script><script type="text/javascript" src="/js/fix-location.js"></script><link rel="stylesheet" href="/css/main.css"/><script src="/js/codetabs.js"></script></head><body class="sideNavVisible separateOnPageNav"><div class="fixedHeaderContainer"><div class="headerWrapper wrapper"><header><a href="/"><img class="logo" src="/img/HeronTextLogo-small.png" alt="Apache Heron"/><h2 class="headerTitleWithLogo">Apache Heron</h2></a><a href="/versions"><h3>0.20.5-incubating</h3></a><div class="navigationWrapper navigationSlider"><nav class="slidingNav"><ul class="nav-site nav-site-internal"><li class=""><a href="/api/java" target="_self">Javadocs</a></li><li class=""><a href="/api/python" target="_self">Pydocs</a></li><li class="siteNavGroupActive"><a href="/docs/getting-started-local-single-node" target="_self">Docs</a></li><li class=""><a href="/download" target="_self">Downloads</a></li><li class=""><a href="#community" target="_self">Community</a></li><li class=""><a href="/blog/" target="_self">Blog</a></li><li class=""><a href="#apache" target="_self">Apache</a></li></ul></nav></div></header></div></div><div class="navPusher"><div class="docMainWrapper wrapper"><div class="container docsNavContainer" id="docsNav"><nav class="toc"><div class="toggleNav"><section class="navWrapper wrapper"><div class="navBreadcrumb wrapper"><div class="navToggle" id="navToggler"><div class="hamburger-menu"><div class="line1"></div><div class="line2"></div><div class="line3"></div></div></div><h2><i>›</i><span>Guides</span></h2><div class="tocToggler" id="tocToggler"><i class="icon-toc"></i></div></div><div class="navGroups"><div class="navGroup"><h3 class="navGroupCategoryTitle">Getting Started</h3><ul class=""><li class="navListItem"><a class="navItem" href="/docs/getting-started-local-single-node">Local (Single Node)</a></li><li class="navListItem"><a class="navItem" href="/docs/getting-started-migrate-storm-topologies">Migrate Storm Topologies</a></li><li class="navListItem"><a class="navItem" href="/docs/getting-started-docker">Heron &amp; Docker</a></li><li class="navListItem"><a class="navItem" href="/docs/getting-started-troubleshooting-guide">Troubleshooting Guide</a></li></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle">Deployment</h3><ul class=""><li class="navListItem"><a class="navItem" href="/docs/deployment-overview">Deployment Overiew</a></li><li class="navListItem"><a class="navItem" href="/docs/deployment-configuration">Configuration</a></li><li class="navListItem"><a class="navItem" href="/docs/deployment-api-server">The Heron API Server</a></li></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle">Topology Development APIs</h3><ul class=""><li class="navListItem"><a class="navItem" href="/docs/topology-development-streamlet-api">The Heron Streamlet API for Java</a></li><li class="navListItem"><a class="navItem" href="/docs/topology-development-eco-api">The ECO API for Java</a></li><li class="navListItem"><a class="navItem" href="/docs/topology-development-topology-api-java">The Heron Topology API for Java</a></li><li class="navListItem"><a class="navItem" href="/docs/topology-development-topology-api-python">The Heron Topology API for Python</a></li><li class="navListItem"><a class="navItem" href="/docs/topology-development-streamlet-scala">The Heron Streamlet API for Scala</a></li></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle">Client API Docs</h3><ul class=""><li class="navListItem"><a class="navItem" href="/docs/client-api-docs-overview">Client API Docs</a></li></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle">Guides</h3><ul class=""><li class="navListItem"><a class="navItem" href="/docs/guides-effectively-once-java-topologies">Effectively Once Java Topologies</a></li><li class="navListItem"><a class="navItem" href="/docs/guides-data-model">Heron Data Model</a></li><li class="navListItem"><a class="navItem" href="/docs/guides-tuple-serialization">Tuple Serialization</a></li><li class="navListItem"><a class="navItem" href="/docs/guides-ui-guide">Heron UI Guide</a></li><li class="navListItem"><a class="navItem" href="/docs/guides-topology-tuning">Topology Tuning Guide</a></li><li class="navListItem"><a class="navItem" href="/docs/guides-packing-algorithms">Packing Algorithms</a></li><li class="navListItem navListItemActive"><a class="navItem" href="/docs/guides-simulator-mode">Simulator Mode</a></li><li class="navListItem"><a class="navItem" href="/docs/guides-troubeshooting-guide">Topology Troubleshooting Guide</a></li></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle">Heron Concepts</h3><ul class=""><li class="navListItem"><a class="navItem" href="/docs/heron-design-goals">Heron Design Goals</a></li><li class="navListItem"><a class="navItem" href="/docs/heron-topology-concepts">Heron Topologies</a></li><li class="navListItem"><a class="navItem" href="/docs/heron-streamlet-concepts">Heron Streamlets</a></li><li class="navListItem"><a class="navItem" href="/docs/heron-architecture">Heron Architecture</a></li><li class="navListItem"><a class="navItem" href="/docs/heron-delivery-semantics">Heron Delivery Semantics</a></li></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle">State Managers</h3><ul class=""><li class="navListItem"><a class="navItem" href="/docs/state-managers-zookeeper">Zookeeper</a></li><li class="navListItem"><a class="navItem" href="/docs/state-managers-local-fs">Local File System</a></li></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle">Uploaders</h3><ul class=""><li class="navListItem"><a class="navItem" href="/docs/uploaders-local-fs">Local File System</a></li><li class="navListItem"><a class="navItem" href="/docs/uploaders-hdfs">HDFS</a></li><li class="navListItem"><a class="navItem" href="/docs/uploaders-http">HTTP</a></li><li class="navListItem"><a class="navItem" href="/docs/uploaders-amazon-s3">Amazon S3</a></li><li class="navListItem"><a class="navItem" href="/docs/uploaders-scp">Secure Copy (SCP)</a></li></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle">Schedulers</h3><ul class=""><li class="navListItem"><a class="navItem" href="/docs/schedulers-k8s-by-hand">Kubernetes by hand</a></li><li class="navListItem"><a class="navItem" href="/docs/schedulers-k8s-with-helm">Kubernetes with Helm</a></li><li class="navListItem"><a class="navItem" href="/docs/schedulers-k8s-execution-environment">Kubernetes Environment Customization</a></li><li class="navListItem"><a class="navItem" href="/docs/schedulers-aurora-cluster">Aurora Cluster</a></li><li class="navListItem"><a class="navItem" href="/docs/schedulers-aurora-local">Aurora Locally</a></li><li class="navListItem"><a class="navItem" href="/docs/schedulers-local">Local Cluster</a></li><li class="navListItem"><a class="navItem" href="/docs/schedulers-nomad">Nomad</a></li><li class="navListItem"><a class="navItem" href="/docs/schedulers-mesos-local-mac">Mesos Cluster Locally</a></li><li class="navListItem"><a class="navItem" href="/docs/schedulers-slurm">Slurm Cluster</a></li><li class="navListItem"><a class="navItem" href="/docs/schedulers-yarn">YARN Cluster</a></li></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle">Cluster Configuration</h3><ul class=""><li class="navListItem"><a class="navItem" href="/docs/cluster-config-overview">Cluster Config Overview</a></li><li class="navListItem"><a class="navItem" href="/docs/cluster-config-system-level">System Level Configuration</a></li><li class="navListItem"><a class="navItem" href="/docs/cluster-config-instance">Heron Instance</a></li><li class="navListItem"><a class="navItem" href="/docs/cluster-config-metrics">Metrics Manager</a></li><li class="navListItem"><a class="navItem" href="/docs/cluster-config-stream">Stream Manager</a></li><li class="navListItem"><a class="navItem" href="/docs/cluster-config-tmanager">Topology Manager</a></li></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle">Observability</h3><ul class=""><li class="navListItem"><a class="navItem" href="/docs/observability-prometheus">Prometheus</a></li><li class="navListItem"><a class="navItem" href="/docs/observability-graphite">Graphite</a></li><li class="navListItem"><a class="navItem" href="/docs/observability-scribe">Scribe</a></li></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle">User Manuals</h3><ul class=""><li class="navListItem"><a class="navItem" href="/docs/user-manuals-heron-cli">Heron Client</a></li><li class="navListItem"><a class="navItem" href="/docs/user-manuals-heron-explorer">Heron Explorer</a></li><li class="navListItem"><a class="navItem" href="/docs/user-manuals-tracker-rest">Heron Tracker REST API</a></li><li class="navListItem"><a class="navItem" href="/docs/user-manuals-heron-tracker-runbook">Heron Tracker Runbook</a></li><li class="navListItem"><a class="navItem" href="/docs/user-manuals-heron-ui-runbook">Heron UI Runbook</a></li><li class="navListItem"><a class="navItem" href="/docs/user-manuals-heron-shell">Heron Shell</a></li></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle">Compiling</h3><ul class=""><li class="navListItem"><a class="navItem" href="/docs/compiling-overview">Compiling Overview</a></li><li class="navListItem"><a class="navItem" href="/docs/compiling-linux">Compiling on Linux</a></li><li class="navListItem"><a class="navItem" href="/docs/compiling-osx">Compiling on OS X</a></li><li class="navListItem"><a class="navItem" href="/docs/compiling-docker">Compiling With Docker</a></li><li class="navListItem"><a class="navItem" href="/docs/compiling-running-tests">Running Tests</a></li><li class="navListItem"><a class="navItem" href="/docs/compiling-code-organization">Code Organization</a></li></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle">Extending Heron</h3><ul class=""><li class="navListItem"><a class="navItem" href="/docs/extending-heron-scheduler">Custom Scheduler</a></li><li class="navListItem"><a class="navItem" href="/docs/extending-heron-metric-sink">Custom Metrics Sink</a></li></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle">Heron Resources</h3><ul class=""><li class="navListItem"><a class="navItem" href="/docs/heron-resources-resources">Heron Resources</a></li></ul></div></div></section></div><script>
            var coll = document.getElementsByClassName('collapsible');
            var checkActiveCategory = true;
            for (var i = 0; i < coll.length; i++) {
              var links = coll[i].nextElementSibling.getElementsByTagName('*');
              if (checkActiveCategory){
                for (var j = 0; j < links.length; j++) {
                  if (links[j].classList.contains('navListItemActive')){
                    coll[i].nextElementSibling.classList.toggle('hide');
                    coll[i].childNodes[1].classList.toggle('rotate');
                    checkActiveCategory = false;
                    break;
                  }
                }
              }

              coll[i].addEventListener('click', function() {
                var arrow = this.childNodes[1];
                arrow.classList.toggle('rotate');
                var content = this.nextElementSibling;
                content.classList.toggle('hide');
              });
            }

            document.addEventListener('DOMContentLoaded', function() {
              createToggler('#navToggler', '#docsNav', 'docsSliderActive');
              createToggler('#tocToggler', 'body', 'tocActive');

              var headings = document.querySelector('.toc-headings');
              headings && headings.addEventListener('click', function(event) {
                var el = event.target;
                while(el !== headings){
                  if (el.tagName === 'A') {
                    document.body.classList.remove('tocActive');
                    break;
                  } else{
                    el = el.parentNode;
                  }
                }
              }, false);

              function createToggler(togglerSelector, targetSelector, className) {
                var toggler = document.querySelector(togglerSelector);
                var target = document.querySelector(targetSelector);

                if (!toggler) {
                  return;
                }

                toggler.onclick = function(event) {
                  event.preventDefault();

                  target.classList.toggle(className);
                };
              }
            });
        </script></nav></div><div class="container mainContainer"><div class="wrapper"><div class="post"><header class="postHeader"><h1 class="postHeaderTitle">Simulator Mode</h1></header><article><div><span><!--
    Licensed to the Apache Software Foundation (ASF) under one
    or more contributor license agreements.  See the NOTICE file
    distributed with this work for additional information
    regarding copyright ownership.  The ASF licenses this file
    to you under the Apache License, Version 2.0 (the
    "License"); you may not use this file except in compliance
    with the License.  You may obtain a copy of the License at
      http://www.apache.org/licenses/LICENSE-2.0
    Unless required by applicable law or agreed to in writing,
    software distributed under the License is distributed on an
    "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    KIND, either express or implied.  See the License for the
    specific language governing permissions and limitations
    under the License.
-->
<p>Simulator mode is specifically designed for topology developers to easily debug or optimize their
topologies.</p>
<p>Simulator mode simulates a heron cluster in a single JVM process, which is useful for developing and
testing topologies. Running topologies under simulator mode is similar to running topologies on a
cluster.</p>
<h1><a class="anchor" aria-hidden="true" id="develop-a-topology-using-simulator-mode"></a><a href="#develop-a-topology-using-simulator-mode" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Develop a topology using simulator mode</h1>
<p>To run in simulator mode, use the <code>SimulatorMode</code> class, which is
in <code>storm-compatibility-unshaded_deploy.jar</code>  (under <code>bazel-bin/storm-compatibility/v0.10.2/src/java</code>).</p>
<p>For example:</p>
<pre><code class="hljs css language-java"><span class="hljs-keyword">import</span> org.apache.heron.simulator.Simulator;
Simulator simulator = <span class="hljs-keyword">new</span> Simulator();
</code></pre>
<p>You can then submit topologies using the <code>submitTopology</code> method on the <code>Simulator</code> object. Just
like the corresponding method on <code>StormSubmitter</code>, <code>submitTopology</code> takes a name, a topology
configuration, and a topology object.</p>
<p>For example:</p>
<pre><code class="hljs css language-java">simulator.submitTopology(<span class="hljs-string">"test"</span>, conf, builder.createTopology());
</code></pre>
<p>Other lifecycle methods to use with simulator mode are:</p>
<pre><code class="hljs css language-java">simulator.killTopology(<span class="hljs-string">"test"</span>);
simulator.activate(<span class="hljs-string">"test"</span>);
simulator.deactivate(<span class="hljs-string">"test"</span>);
simulator.shutdown();
</code></pre>
<p>To kill a topology, one could also terminate the process.</p>
<p>The simulator mode will run in separate threads other than the main thread. All the above methods are
thread-safe. This means that one could invoke these methods in other threads and monitor the
corresponding behaviors interactively.</p>
<h1><a class="anchor" aria-hidden="true" id="debug-topology-using-intellij"></a><a href="#debug-topology-using-intellij" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Debug topology using IntelliJ</h1>
<p>Bolts and Spouts run as separate threads in simulator. To add breakpoints inside a bolt/spout, the
Suspend Policy of the breakpoint needs to be set to Thread. To change the Suspend Policy, right
click on the breakpoint as shown in the following image:</p>
<p><img src="/docs/assets/intellij-set-breakpoint.jpg" alt="Set Breakpoint"></p>
<p>If it's not convenient to check the output and logs in the IntelliJ console, save them to a local file
by choosing <code>Run -&gt; Edit Configurations....</code> as shown in the following image:</p>
<p><img src="/docs/assets/intellij-save-console.jpg" alt="Save Console"></p>
</span></div></article></div><div class="docs-prevnext"><a class="docs-prev button" href="/docs/guides-packing-algorithms"><span class="arrow-prev">← </span><span>Packing Algorithms</span></a><a class="docs-next button" href="/docs/guides-troubeshooting-guide"><span>Topology Troubleshooting Guide</span><span class="arrow-next"> →</span></a></div></div></div><nav class="onPageNav"></nav></div><footer class="nav-footer" id="footer"><div class="apache-disclaimer">Apache Heron is an effort undergoing incubation at <a target="_blank" href="https://apache.org/">The Apache Software Foundation (ASF)</a> sponsored by the Apache Incubator PMC. Incubation is required of all newly accepted projects until a further review indicates that the infrastructure, communications, and decision making process have stabilized in a manner consistent with other successful ASF projects. While incubation status is not necessarily a reflection of the completeness or stability of the code, it does indicate that the project has yet to be fully endorsed by the ASF.<br/><br/>Apache®, the names of Apache projects, and the feather logo are either <a rel="external" href="https://www.apache.org/foundation/marks/list/">registered trademarks or trademarks</a> of the Apache Software Foundation in the United States and/or other countries.<br/><br/><div class="copyright-box">Copyright © 2023 the Apache Software Foundation, Apache Heron, Heron, 
  Apache, the Apache feather Logo, and the Apache Heron project logo are either registered 
  trademarks or trademarks of the Apache Software Foundation.</div></div><div class="apache-links"><a class="item" rel="external" href="https://incubator.apache.org/">Apache Incubator</a><div><a class="item" rel="external" href="https://www.apache.org/">About the ASF</a></div><div><a class="item" rel="external" href="https://www.apache.org/events/current-event">Events</a></div><div><a class="item" rel="external" href="https://www.apache.org/foundation/thanks.html">Thanks</a></div><div><a class="item" rel="external" href="https://www.apache.org/foundation/sponsorship.html">Become a Sponsor</a></div><div><a class="item" rel="external" href="https://www.apache.org/security/">Security</a></div><div><a class="item" rel="external" href="https://www.apache.org/licenses/">License</a></div></div></footer></div><script>window.twttr=(function(d,s, id){var js,fjs=d.getElementsByTagName(s)[0],t=window.twttr||{};if(d.getElementById(id))return t;js=d.createElement(s);js.id=id;js.src='https://platform.twitter.com/widgets.js';fjs.parentNode.insertBefore(js, fjs);t._e = [];t.ready = function(f) {t._e.push(f);};return t;}(document, 'script', 'twitter-wjs'));</script></body></html>