docs/topics/impala_webui.xml

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<!DOCTYPE concept PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">
<concept id="webui">

  <title id="webui_title">Impala Web User Interface for Debugging</title>
  <titlealts audience="PDF"><navtitle>Web User Interface</navtitle></titlealts>
  <prolog>
    <metadata>
      <data name="Category" value="Impala"/>
      <data name="Category" value="Troubleshooting"/>
      <data name="Category" value="Administrators"/>
      <data name="Category" value="Developers"/>
      <data name="Category" value="Data Analysts"/>
    </metadata>
  </prolog>

  <conbody>

    <p id="webui_intro">
      <indexterm audience="hidden">web UI</indexterm>
      <indexterm audience="hidden">debug UI</indexterm>
      Each of the Impala daemons (<cmdname>impalad</cmdname>, <cmdname>statestored</cmdname>,
      and <cmdname>catalogd</cmdname>) includes a built-in web server that displays
      diagnostic and status information:
      <ul>
      <li>
        <p>
          The <cmdname>impalad</cmdname> web UI (default port: 25000) includes
          information about configuration settings, running and completed queries, and associated performance and
          resource usage for queries. In particular, the <uicontrol>Details</uicontrol> link for each query displays
          alternative views of the query including a graphical representation of the plan, and the
          output of the <codeph>EXPLAIN</codeph>, <codeph>SUMMARY</codeph>, and <codeph>PROFILE</codeph>
          statements from <cmdname>impala-shell</cmdname>.
          Each host that runs the <cmdname>impalad</cmdname> daemon has
          its own instance of the web UI, with details about those queries for which that
          host served as the coordinator. The <cmdname>impalad</cmdname> web UI is mainly
          for diagnosing query problems that can be traced to a particular node.
        </p>
      </li>
      <li>
        <p>
          The <cmdname>statestored</cmdname> web UI (default port: 25010) includes
          information about memory usage, configuration settings, and ongoing health checks
          performed by this daemon. Because there is only a single instance of this
          daemon within any cluster, you view the web UI only on the particular host
          that serves as the Impala Statestore.
        </p>
      </li>
      <li>
        <p>
          The <cmdname>catalogd</cmdname> web UI (default port: 25020) includes
          information about the databases, tables, and other objects managed by Impala,
          in addition to the resource usage and configuration settings of the daemon itself.
          The catalog information is represented as the underlying Thrift data structures.
          Because there is only a single instance of this daemon within any cluster, you view the
          web UI only on the particular host that serves as the Impala Catalog Server.
        </p>
      </li>
      </ul>
    </p>

    <note>
      <p>
        The web user interface is primarily for problem diagnosis and troubleshooting. The items listed and their
        formats are subject to change.
      </p>
    </note>

    <p outputclass="toc inpage"/>
  </conbody>

  <concept id="webui_impalad">

    <title>Debug Web UI for impalad</title>

    <conbody>

      <p>
        To debug and troubleshoot the <cmdname>impalad</cmdname> daemon using a web-based interface, open the URL
        <codeph>http://<varname>impala-server-hostname</varname>:25000/</codeph> in a browser. (For secure
        clusters, use the prefix <codeph>https://</codeph> instead of <codeph>http://</codeph>.) Because each
        Impala node produces its own set of debug information, choose a specific node that you are curious about or
        suspect is having problems.
      </p>

    </conbody>

    <concept audience="hidden" id="webui_impalad_disabling">

      <title>Turning off the Web UI for impalad</title>

      <conbody>

        <p></p>
      </conbody>
    </concept>

    <concept id="webui_impalad_main">

      <title>Main Page</title>

      <conbody>

        <p>
          By default, the main page of the debug web UI is at
          <codeph>http://<varname>impala-server-hostname</varname>:25000/</codeph> (non-secure cluster) or
          <codeph>https://<varname>impala-server-hostname</varname>:25000/</codeph> (secure cluster).
        </p>

        <p>
          This page lists the version of the <cmdname>impalad</cmdname> daemon, plus basic hardware and software
          information about the corresponding host, such as information about the CPU, memory, disks, and operating
          system version.
        </p>
      </conbody>
    </concept>

    <concept id="webui_impalad_backends">

      <title>Backends Page</title>

      <conbody>

        <p>
          By default, the <uicontrol>backends</uicontrol> page of the debug web UI is at
          <codeph>http://<varname>impala-server-hostname</varname>:25000/backends</codeph> (non-secure cluster) or
          <codeph>https://<varname>impala-server-hostname</varname>:25000/backends</codeph> (secure cluster).
        </p>

        <p>
          This page lists the host and port info for each of the <cmdname>impalad</cmdname> nodes in the cluster.
          Because each <cmdname>impalad</cmdname> daemon knows about every other <cmdname>impalad</cmdname> daemon
          through the statestore, this information should be the same regardless of which node you select. Links
          take you to the corresponding debug web pages for any of the other nodes in the cluster.
        </p>
      </conbody>
    </concept>

    <concept id="webui_impalad_catalog">

      <title>Catalog Page</title>

      <conbody>

        <p>
          By default, the <uicontrol>catalog</uicontrol> page of the debug web UI is at
          <codeph>http://<varname>impala-server-hostname</varname>:25000/catalog</codeph> (non-secure cluster) or
          <codeph>https://<varname>impala-server-hostname</varname>:25000/catalog</codeph> (secure cluster).
        </p>

        <p>
          This page displays a list of databases and associated tables recognized by this instance of
          <cmdname>impalad</cmdname>. You can use this page to locate which database a table is in, check the
          exact spelling of a database or table name, look for identical table names in multiple databases, and so
          on.
        </p>
      </conbody>
    </concept>

    <concept id="webui_impalad_logs">

      <title>Logs Page</title>
  <prolog>
    <metadata>
      <data name="Category" value="Logs"/>
    </metadata>
  </prolog>

      <conbody>

        <p>
          By default, the <uicontrol>logs</uicontrol> page of the debug web UI is at
          <codeph>http://<varname>impala-server-hostname</varname>:25000/logs</codeph> (non-secure cluster) or
          <codeph>https://<varname>impala-server-hostname</varname>:25000/logs</codeph> (secure cluster).
        </p>

        <p>
          This page shows the last portion of the <filepath>impalad.INFO</filepath> log file, the most detailed of
          the info, warning, and error logs for the <cmdname>impalad</cmdname> daemon. You can refer here to see
          the details of the most recent operations, whether the operations succeeded or encountered errors. This
          central page can be more convenient than looking around the filesystem for the log files, which could be
          in different locations on clusters that use cluster management software.
        </p>

      </conbody>
    </concept>

    <concept id="webui_impalad_memz">

      <title>Memz Page</title>

      <conbody>

        <p>
          By default, the <uicontrol>memz</uicontrol> page of the debug web UI is at
          <codeph>http://<varname>impala-server-hostname</varname>:25000/memz</codeph> (non-secure cluster) or
          <codeph>https://<varname>impala-server-hostname</varname>:25000/memz</codeph> (secure cluster).
        </p>

        <p>
          This page displays summary and detailed information about memory usage by the <cmdname>impalad</cmdname>
          daemon. You can see the memory limit in effect for the node, and how much of that memory Impala is
          currently using.
        </p>
      </conbody>
    </concept>

    <concept id="webui_impalad_metrics">

      <title>Metrics Page</title>

      <conbody>

        <p>
          By default, the <uicontrol>metrics</uicontrol> page of the debug web UI is at
          <codeph>http://<varname>impala-server-hostname</varname>:25000/metrics</codeph> (non-secure cluster) or
          <codeph>https://<varname>impala-server-hostname</varname>:25000/metrics</codeph> (secure cluster).
        </p>

        <p>
          This page displays the current set of metrics: counters and flags representing various aspects of
          <cmdname>impalad</cmdname> internal operation.
        </p>

      </conbody>
    </concept>

    <concept id="webui_impalad_queries">

      <title>Queries Page</title>

      <conbody>

        <p>
          By default, the <uicontrol>queries</uicontrol> page of the debug web UI is at
          <codeph>http://<varname>impala-server-hostname</varname>:25000/queries</codeph> (non-secure cluster) or
          <codeph>https://<varname>impala-server-hostname</varname>:25000/queries</codeph> (secure cluster).
        </p>

        <p>
          This page lists all currently running queries, plus any completed queries whose details still reside in
          memory. The queries are listed in reverse chronological order, with the most recent at the top. (You can
          control the amount of memory devoted to completed queries by specifying the
          <codeph>--query_log_size</codeph> startup option for <cmdname>impalad</cmdname>.)
        </p>

        <p>
          On this page, you can see at a glance how many SQL statements are failing (<codeph>State</codeph> value
          of <codeph>EXCEPTION</codeph>), how large the result sets are (<codeph># rows fetched</codeph>), and how
          long each statement took (<codeph>Start Time</codeph> and <codeph>End Time</codeph>).
        </p>

        <p>
          Each query has an associated link that displays the detailed query profile, which you can examine to
          understand the performance characteristics of that query. See
          <xref href="impala_explain_plan.xml#perf_profile"/> for details.
        </p>
      </conbody>
    </concept>

    <concept id="webui_impalad_sessions">

      <title>Sessions Page</title>

      <conbody>

        <p>
          By default, the <uicontrol>sessions</uicontrol> page of the debug web UI is at
          <codeph>http://<varname>impala-server-hostname</varname>:25000/sessions</codeph> (non-secure cluster) or
          <codeph>https://<varname>impala-server-hostname</varname>:25000/sessions</codeph> (secure cluster).
        </p>

        <p>
          This page displays information about the sessions currently connected to this <cmdname>impalad</cmdname>
          instance. For example, sessions could include connections from the <cmdname>impala-shell</cmdname>
          command, JDBC or ODBC applications, or the Impala Query UI in the Hue web interface.
        </p>
      </conbody>
    </concept>

    <concept id="webui_impalad_threadz">

      <title>Threadz Page</title>

      <conbody>

        <p>
          By default, the <uicontrol>threadz</uicontrol> page of the debug web UI is at
          <codeph>http://<varname>impala-server-hostname</varname>:25000/threadz</codeph> (non-secure cluster) or
          <codeph>https://<varname>impala-server-hostname</varname>:25000/threadz</codeph> (secure cluster).
        </p>

        <p>
          This page displays information about the threads used by this instance of <cmdname>impalad</cmdname>,
          and shows which categories they are grouped into. Making use of this information requires substantial
          knowledge about Impala internals.
        </p>
      </conbody>
    </concept>

    <concept id="webui_impalad_varz">

      <title>Varz Page</title>

      <conbody>

        <p>
          By default, the <uicontrol>varz</uicontrol> page of the debug web UI is at
          <codeph>http://<varname>impala-server-hostname</varname>:25000/varz</codeph> (non-secure cluster) or
          <codeph>https://<varname>impala-server-hostname</varname>:25000/varz</codeph> (secure cluster).
        </p>

        <p>
          This page shows the configuration settings in effect when this instance of <cmdname>impalad</cmdname>
          communicates with other Hadoop components such as HDFS and YARN. These settings are collected from a set
          of configuration files; Impala might not actually make use of all settings.
        </p>

        <p>
          The bottom of this page also lists all the command-line settings in effect for this instance of
          <cmdname>impalad</cmdname>. See <xref href="impala_config_options.xml#config_options"/> for information
          about modifying these values.
        </p>
      </conbody>
    </concept>
  </concept>

  <concept audience="hidden" id="webui_statestored">

    <title>Debug Web UI for statestored</title>

    <conbody>

      <p></p>
    </conbody>

    <concept audience="hidden" id="webui_statestored_disabling">

      <title>Turning off the Web UI for statestored</title>

      <conbody>

        <p></p>
      </conbody>
    </concept>

    <concept id="webui_statestored_main">

      <title>Main Page</title>

      <conbody>

        <p>
          By default, the main page of the debug web UI is at
          <codeph>http://<varname>impala-server-hostname</varname>:25010/</codeph> (non-secure cluster) or
          <codeph>https://<varname>impala-server-hostname</varname>:25010/</codeph> (secure cluster).
        </p>

        <p>
          This page lists the version of the <cmdname>impalad</cmdname> daemon, plus basic hardware and software
          information about the corresponding host, such as information about the CPU, memory, disks, and operating
          system version.
        </p>
      </conbody>
    </concept>

    <concept id="webui_statestored_logs">

      <title>Logs Page</title>

      <conbody>

        <p>
          By default, the <uicontrol>logs</uicontrol> page of the debug web UI is at
          <codeph>http://<varname>impala-server-hostname</varname>:25010/logs</codeph> (non-secure cluster) or
          <codeph>https://<varname>impala-server-hostname</varname>:25010/logs</codeph> (secure cluster).
        </p>

        <p>
          This page shows the last portion of the <filepath>impalad.INFO</filepath> log file, the most detailed of
          the info, warning, and error logs for the <cmdname>impalad</cmdname> daemon. You can refer here to see
          the details of the most recent operations, whether the operations succeeded or encountered errors. This
          central page can be more convenient than looking around the filesystem for the log files, which could be
          in different locations on different hosts.
        </p>
      </conbody>
    </concept>

    <concept id="webui_statestored_memz">

      <title>Memz Page</title>

      <conbody>

        <p>
          By default, the <uicontrol>memz</uicontrol> page of the debug web UI is at
          <codeph>http://<varname>impala-server-hostname</varname>:25010/memz</codeph> (non-secure cluster) or
          <codeph>https://<varname>impala-server-hostname</varname>:25010/memz</codeph> (secure cluster).
        </p>

        <p>
          This page displays summary and detailed information about memory usage by the <cmdname>impalad</cmdname>
          daemon. You can see the memory limit in effect for the node, and how much of that memory Impala is
          currently using.
        </p>
      </conbody>
    </concept>

    <concept id="webui_statestored_metrics">

      <title>Metrics Page</title>

      <conbody>

        <p>
          By default, the <uicontrol>metrics</uicontrol> page of the debug web UI is at
          <codeph>http://<varname>impala-server-hostname</varname>:25010/metrics</codeph> (non-secure cluster) or
          <codeph>https://<varname>impala-server-hostname</varname>:25010/metrics</codeph> (secure cluster).
        </p>

        <p>
          This page displays the current set of metrics: counters and flags representing various aspects of
          <cmdname>impalad</cmdname> internal operation.
        </p>
      </conbody>
    </concept>

    <concept id="webui_statestored_subscribers">

      <title>Subscribers Page</title>

      <conbody>

        <p>
          By default, the <uicontrol>subscribers</uicontrol> page of the debug web UI is at
          <codeph>http://<varname>impala-server-hostname</varname>:25010/subscribers</codeph> (non-secure cluster)
          or <codeph>https://<varname>impala-server-hostname</varname>:25010/subscribers</codeph> (secure cluster).
        </p>

        <p>
          This page displays information about...
        </p>
      </conbody>
    </concept>

    <concept id="webui_statestored_threadz">

      <title>Threadz Page</title>

      <conbody>

        <p>
          By default, the <uicontrol>threadz</uicontrol> page of the debug web UI is at
          <codeph>http://<varname>impala-server-hostname</varname>:25010/threadz</codeph> (non-secure cluster) or
          <codeph>https://<varname>impala-server-hostname</varname>:25010/threadz</codeph> (secure cluster).
        </p>

        <p>
          This page displays information about the threads used by this instance of <cmdname>impalad</cmdname>,
          and shows which categories they are grouped into. Making use of this information requires substantial
          knowledge about Impala internals.
        </p>
      </conbody>
    </concept>

    <concept id="webui_statestored_topics">

      <title>Topics Page</title>

      <conbody>

        <p>
          By default, the <uicontrol>topics</uicontrol> page of the debug web UI is at
          <codeph>http://<varname>impala-server-hostname</varname>:25010/topics</codeph> (non-secure cluster) or
          <codeph>https://<varname>impala-server-hostname</varname>:25010/topics</codeph> (secure cluster).
        </p>

        <p>
          This page displays information about...
        </p>
      </conbody>
    </concept>

    <concept id="webui_statestored_varz">

      <title>Varz Page</title>

      <conbody>

        <p>
          By default, the <uicontrol>varz</uicontrol> page of the debug web UI is at
          <codeph>http://<varname>impala-server-hostname</varname>:25010/varz</codeph> (non-secure cluster) or
          <codeph>https://<varname>impala-server-hostname</varname>:25010/varz</codeph> (secure cluster).
        </p>

        <p>
          This page shows the configuration settings in effect when this instance of <cmdname>impalad</cmdname>
          communicates with other Hadoop components such as HDFS and YARN. These settings are collected from a set
          of configuration files; Impala might not actually make use of all settings.
        </p>

        <p>
          The bottom of this page also lists all the command-line settings in effect for this instance of
          <cmdname>impalad</cmdname>. See <xref href="impala_config_options.xml#config_options"/> for information
          about modifying these values.
        </p>
      </conbody>
    </concept>
  </concept>

  <concept audience="hidden" id="webui_catalogd">

    <title>Debug Web UI for catalogd</title>

    <conbody>

      <p></p>
    </conbody>

    <concept audience="hidden" id="webui_catalogd_disabling">

      <title>Turning off the Web UI for impalad</title>

      <conbody>

        <p></p>
      </conbody>
    </concept>

    <concept id="webui_catalogd_main">

      <title>Main Page</title>

      <conbody>

        <p>
          By default, the main page of the debug web UI is at
          <codeph>http://<varname>impala-server-hostname</varname>:25020/</codeph> (non-secure cluster) or
          <codeph>https://<varname>impala-server-hostname</varname>:25020/</codeph> (secure cluster).
        </p>

        <p>
          This page lists the version of the <cmdname>impalad</cmdname> daemon, plus basic hardware and software
          information about the corresponding host, such as information about the CPU, memory, disks, and operating
          system version.
        </p>
      </conbody>
    </concept>

    <concept id="webui_catalogd_catalog">

      <title>Catalog Page</title>

      <conbody>

        <p>
          By default, the <uicontrol>catalog</uicontrol> page of the debug web UI is at
          <codeph>http://<varname>impala-server-hostname</varname>:25020/catalog</codeph> (non-secure cluster) or
          <codeph>https://<varname>impala-server-hostname</varname>:25020/catalog</codeph> (secure cluster).
        </p>

        <p>
          This page displays a list of databases and associated tables recognized by this instance of
          <cmdname>impalad</cmdname>. You can use this page to locate which database a table is in, check the
          exact spelling of a database or table name, look for identical table names in multiple databases, and so
          on.
        </p>
      </conbody>
    </concept>

    <concept id="webui_catalogd_logs">

      <title>Logs Page</title>

      <conbody>

        <p>
          By default, the <uicontrol>logs</uicontrol> page of the debug web UI is at
          <codeph>http://<varname>impala-server-hostname</varname>:25020/logs</codeph> (non-secure cluster) or
          <codeph>https://<varname>impala-server-hostname</varname>:25020/logs</codeph> (secure cluster).
        </p>

        <p>
          This page shows the last portion of the <filepath>impalad.INFO</filepath> log file, the most detailed of
          the info, warning, and error logs for the <cmdname>impalad</cmdname> daemon. You can refer here to see
          the details of the most recent operations, whether the operations succeeded or encountered errors. This
          central page can be more convenient than looking around the filesystem for the log files, which could be
          in different locations on different hosts.
        </p>
      </conbody>
    </concept>

    <concept id="webui_catalogd_metrics">

      <title>Metrics Page</title>

      <conbody>

        <p>
          By default, the <uicontrol>metrics</uicontrol> page of the debug web UI is at
          <codeph>http://<varname>impala-server-hostname</varname>:25020/metrics</codeph> (non-secure cluster) or
          <codeph>https://<varname>impala-server-hostname</varname>:25020/metrics</codeph> (secure cluster).
        </p>

        <p>
          This page displays the current set of metrics: counters and flags representing various aspects of
          <cmdname>impalad</cmdname> internal operation.
        </p>
      </conbody>
    </concept>

    <concept id="webui_catalogd_varz">

      <title>Varz Page</title>

      <conbody>

        <p>
          By default, the <uicontrol>varz</uicontrol> page of the debug web UI is at
          <codeph>http://<varname>impala-server-hostname</varname>:25020/varz</codeph> (non-secure cluster) or
          <codeph>https://<varname>impala-server-hostname</varname>:25020/varz</codeph> (secure cluster).
        </p>

        <p>
          This page shows the configuration settings in effect when this instance of <cmdname>impalad</cmdname>
          communicates with other Hadoop components such as HDFS and YARN. These settings are collected from a set
          of configuration files; Impala might not actually make use of all settings.
        </p>

        <p>
          The bottom of this page also lists all the command-line settings in effect for this instance of
          <cmdname>impalad</cmdname>. See <xref href="impala_config_options.xml#config_options"/> for information
          about modifying these values.
        </p>
      </conbody>
    </concept>
  </concept>
</concept>