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    <div class="section" id="application-reset-tool">
        <span id="streams-developer-guide-app-reset"></span><h1>Application Reset Tool<a class="headerlink" href="#application-reset-tool" title="Permalink to this headline"></a></h1>
        <p>You can reset an application and force it to reprocess its data from scratch by using the application reset tool.
            This can be useful for development and testing, or when fixing bugs.</p>
        <p>The application reset tool handles the Kafka Streams <a class="reference internal" href="manage-topics.html#streams-developer-guide-topics-user"><span class="std std-ref">user topics</span></a> (input,
            and output) and <a class="reference internal" href="manage-topics.html#streams-developer-guide-topics-internal"><span class="std std-ref">internal topics</span></a> differently
            when resetting the application.</p>
        <p>Here&#8217;s what the application reset tool does for each topic type:</p>
        <ul class="simple">
            <li>Input topics: Reset offsets to specified position (by default to the beginning of the topic).</li>
            <li>Internal topics: Delete the internal topic (this automatically deletes any committed offsets).</li>
        </ul>
        <p>The application reset tool does not:</p>
        <ul class="simple">
            <li>Reset output topics of an application. If any output topics are consumed by downstream
                applications, it is your responsibility to adjust those downstream applications as appropriate when you reset the
                upstream application.</li>
            <li>Reset the local environment of your application instances.  It is your responsibility to delete the local
                state on any machine on which an application instance was run.  See the instructions in section
                <a class="reference internal" href="#streams-developer-guide-reset-local-environment"><span class="std std-ref">Step 2: Reset the local environments of your application instances</span></a> on how to do this.</li>
        </ul>
        <dl class="docutils">
            <dt>Prerequisites</dt>
            <dd><ul class="first last">
                <li><p class="first">All instances of your application must be stopped. Otherwise, the application may enter an invalid state, crash, or produce incorrect results. You can verify whether the consumer group with ID <code class="docutils literal"><span class="pre">application.id</span></code> is still active by using <code class="docutils literal"><span class="pre">bin/kafka-consumer-groups</span></code>.
                    When long session timeout has been configured, active members could take longer to get expired on the broker thus blocking the reset job to complete. Use the <code class="docutils literal"><span class="pre">--force</span></code> option could remove those left-over members immediately. Make sure to shut down all stream applications when this option is specified to avoid unexpected rebalances.</p>
                </li>
                <li><p class="first">Use this tool with care and double-check its parameters: If you provide wrong parameter values (e.g., typos in <code class="docutils literal"><span class="pre">application.id</span></code>) or specify parameters inconsistently (e.g., specify the wrong input topics for the application), this tool might invalidate the application&#8217;s state or even impact other applications, consumer groups, or your Kafka topics.</p>
                </li>
            </ul>
            </dd>
        </dl>
        <div class="section" id="step-1-run-the-application-reset-tool">
            <h2>Step 1: Run the application reset tool<a class="headerlink" href="#step-1-run-the-application-reset-tool" title="Permalink to this headline"></a></h2>
            <p>Invoke the application reset tool from the command line</p>
            <p>Warning! This tool makes irreversible changes to your application. It is strongly recommended that you run this once with <code class="docutils literal"><span class="pre">--dry-run</span></code> to preview your changes before making them.</p>
            <pre><code class="language-bash">$ bin/kafka-streams-application-reset.sh</code></pre>
            <p>The tool accepts the following parameters:</p>
            <pre><code class="language-text">Option (* = required)                 Description
---------------------                 -----------
* --application-id &lt;String: id&gt;       The Kafka Streams application ID
                                        (application.id).
--bootstrap-server &lt;String: server to  REQUIRED unless --bootstrap-servers
                            connect to&gt;                            (deprecated) is specified. The server
                                         (s) to connect to. The broker list
                                         string in the form HOST1:PORT1,HOST2:
                                         PORT2.
--by-duration &lt;String: urls&gt;          Reset offsets to offset by duration from
                                        current timestamp. Format: &#39;PnDTnHnMnS&#39;
--config-file &lt;String: file name&gt;     Property file containing configs to be
                                        passed to admin clients and embedded
                                        consumer.
--dry-run                             Display the actions that would be
                                        performed without executing the reset
                                        commands.
--from-file &lt;String: urls&gt;            Reset offsets to values defined in CSV
                                        file.
--input-topics &lt;String: list&gt;         Comma-separated list of user input
                                        topics. For these topics, the tool will
                                        reset the offset to the earliest
                                        available offset.
--internal-topics &lt;String: list&gt;      Comma-separated list of internal topics
                                        to delete. Must be a subset of the
                                        internal topics marked for deletion by
                                        the default behaviour (do a dry-run without
                                        this option to view these topics).
--shift-by &lt;Long: number-of-offsets&gt;  Reset offsets shifting current offset by
                                        &#39;n&#39;, where &#39;n&#39; can be positive or
                                        negative
--to-datetime &lt;String&gt;                Reset offsets to offset from datetime.
                                        Format: &#39;YYYY-MM-DDThh:mm:ss.sss&#39;
--to-earliest                         Reset offsets to earliest offset.
--to-latest                           Reset offsets to latest offset.
--to-offset &lt;Long&gt;                    Reset offsets to a specific offset.
--force                               Force removing members of the consumer group
                                      (intended to remove left-over members if
                                      long session timeout was configured).</code></pre>
            <p>Consider the following as reset-offset scenarios for <code>input-topics</code>:</p>
            <ul>
                <li> by-duration</li>
                <li> from-file</li>
                <li> shift-by</li>
                <li> to-datetime</li>
                <li> to-earliest</li>
                <li> to-latest</li>
                <li> to-offset</li>
            </ul>
            <p>Only one of these scenarios can be defined. If not, <code>to-earliest</code> will be executed by default</p>
            <p>All the other parameters can be combined as needed.  For example, if you want to restart an application from an
                empty internal state, but not reprocess previous data, simply omit the parameter <code class="docutils literal"><span class="pre">--input-topics</span></code>.
        </div>
        <div class="section" id="step-2-reset-the-local-environments-of-your-application-instances">
            <span id="streams-developer-guide-reset-local-environment"></span><h2>Step 2: Reset the local environments of your application instances<a class="headerlink" href="#step-2-reset-the-local-environments-of-your-application-instances" title="Permalink to this headline"></a></h2>
            <p>For a complete application reset, you must delete the application&#8217;s local state directory on any machines where the
                application instance was run. You must do this before restarting an application instance on the same machine.  You can
                use either of these methods:</p>
            <ul class="simple">
                <li>The API method <code class="docutils literal"><span class="pre">KafkaStreams#cleanUp()</span></code> in your application code.</li>
                <li>Manually delete the corresponding local state directory (default location: <code class="docutils literal"><span class="pre">/${java.io.tmpdir}/kafka-streams/&lt;application.id&gt;</span></code>). For more information, see <a href="/{{version}}/javadoc/org/apache/kafka/streams/StreamsConfig.html#STATE_DIR_CONFIG">Streams</a> javadocs.</li>
            </ul>
</div>
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