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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">
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.
</p>
<dl>
<dlentry>
<dt>
impalad Web UI
</dt>
<dd>
<p>
The <cmdname>impalad</cmdname> Web UI 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
primarily used for diagnosing query problems that can be traced to a particular
node.
</p>
</dd>
</dlentry>
<dlentry>
<dt>
statestored Web UI
</dt>
<dd>
<p>
The <cmdname>statestored</cmdname> Web UI includes information about memory usage,
configuration settings, and ongoing health checks performed by
<codeph>statestored</codeph>. Because there is only a single instance of the
<codeph>statestored</codeph> within any Impala cluster, you access the Web UI only
on the particular host that serves as the Impala StateStore.
</p>
</dd>
</dlentry>
<dlentry>
<dt>
catalogd Web UI
</dt>
<dd>
<p>
The <cmdname>catalogd</cmdname> Web UI includes information about the databases,
tables, and other objects managed by Impala, in addition to the resource usage and
configuration settings of the <codeph>catalogd</codeph>. Because there is only a
single instance of the <codeph>catalogd</codeph> within any Impala cluster, you
access the Web UI only on the particular host that serves as the Impala Catalog
Server.
</p>
</dd>
</dlentry>
</dl>
<p outputclass="toc inpage"/>
</conbody>
<concept id="concept_xfx_r1t_43b">
<title>Configuring Debug Web UIs</title>
<conbody>
<p/>
</conbody>
<concept id="webui_impalad_disabling">
<title>Turning off the Web UI</title>
<conbody>
<p>
To disable Web UI for the <codeph>impalad</codeph>, <codeph>statestored</codeph>, or
<codeph>catalogd</codeph>:
</p>
<ol>
<li>
Stop the Impala role you want to turn off the Web UI for, <codeph>impalad</codeph>,
<codeph>statestored</codeph>, or <codeph>catalogd</codeph>.
</li>
<li>
Restart the role with the <codeph>&#8209;&#8209;enable_webserver=false</codeph>
startup flag.
</li>
</ol>
</conbody>
</concept>
<concept id="concept_g5j_ydt_43b">
<title>Using Kerberos HTTP SPNEGO Authentication for Web UI</title>
<conbody>
<p>
To provide security through Kerberos, Impala Web UIs support SPNEGO, a protocol for
securing HTTP requests with Kerberos by passing negotiation tokens through HTTP
headers.
</p>
<p>
To enable authorization using SPNEGO, set the
<codeph>--webserver_require_spnego=true</codeph> startup flag and restart the Impala
roles, <codeph>impalad</codeph>, <codeph>statestored</codeph>, or
<codeph>catalogd</codeph>.
</p>
</conbody>
</concept>
</concept>
<concept id="webui_impalad">
<title>Debug Web UI for impalad</title>
<conbody>
<p>
To debug and troubleshoot an <cmdname>impalad</cmdname> using a web-based interface,
open the URL
<codeph>http://<varname>impala&#8209;server&#8209;hostname</varname>:25000/</codeph> in
a browser. (For secure clusters, use the prefix <codeph>https://</codeph> instead of
<codeph>http://</codeph>.)
</p>
<p>
Because each Impala node produces its own set of debug information, you should choose a
specific node that you want to investigate an issue on.
</p>
</conbody>
<concept id="webui_impalad_main">
<title>Main Page</title>
<conbody>
<p>
The main <codeph>impalad</codeph> Web UI page at <b>/</b> lists the following
information about the <codeph>impalad</codeph>:
</p>
<ul>
<li>
The version of the <cmdname>impalad</cmdname> daemon
<p>
The <b>Version</b> section also contains other information, such as when Impala
was built and what build flags were used.
</p>
</li>
<li>
Process start time
</li>
<li>
Hardware information
</li>
<li>
OS information
</li>
<li>
Process information
</li>
<li>
CGroup information
</li>
</ul>
</conbody>
</concept>
<concept id="webui_impalad_admission">
<title>Admission Controller Page</title>
<conbody>
<p>
The <b>Admission Controller</b> <codeph>impalad</codeph> debug Web UI is at
<uicontrol>/admission</uicontrol> page under the main <codeph>impalad</codeph> Web UI.
</p>
<p>
Use the <uicontrol>/admission</uicontrol> page to troubleshoot queued queries and the
admission control.
</p>
<p>
The <uicontrol>admission</uicontrol> page provides the following information about
each resource pool to which queries have been submitted at least once:
</p>
<ul>
<li>
Time since the <codeph>statestored</codeph> received the last update
</li>
<li>
A warning if this <codeph>impalad</codeph> is considered disconnected from the
<codeph>statestored</codeph> and thus the information on this page could be stale.
</li>
<li>
Pool configuration
</li>
<li>
Queued queries submitted to this coordinator, in the order of submission
</li>
<li>
Running queries submitted to this coordinator
</li>
<li>
Pool stats
<ul>
<li>
Average of time in queue: An exponential moving average which represents the
average time in queue over the last 10 to 12 queries. If a query is admitted
immediately, the wait time of 0 is used in calculating this average wait time.
</li>
</ul>
</li>
<li>
Histogram of the distribution of peak memory used by queries admitted to the pool
<p>
Use the histogram to figure out settings for the minimum and maximum query
<codeph>MEM_LIMIT</codeph> ranges for this pool.
</p>
<p>
The histogram displays data for all queries admitted to the pool, including the
queries that finished, got canceled, or hit an error.
</p>
</li>
</ul>
<p>
Click on the pool name to only display information relevant to that pool. You can then
refresh the debug page to see only the information for that specific pool.
</p>
<p>
Click <b>Reset informational stats for all pools</b> to reset the stats that keep
track of historical data, such as <b>Totals</b> stats, <b>Time in queue (exponential
moving average)</b>, and the histogram.
</p>
<p>
The above information is also available as a JSON object from the following HTTP
endpoint:
<codeblock><codeph>http://<varname>impala-server-hostname</varname>:<varname>port</varname>/admission?json</codeph></codeblock>
</p>
<p>
See <xref href="impala_admission.xml#admission_control"/> for the description of the
properties in admission control.
</p>
</conbody>
</concept>
<concept id="webui_impalad_backends">
<title>Known Backends Page</title>
<conbody>
<p>
The <b>Known backends</b> page of the <codeph>impalad</codeph> debug Web UI is at
<b>/backends</b> under the main <codeph>impalad</codeph> Web UI.
</p>
<p>
This page lists the following 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.
</p>
<ul>
<li>
Address of the node: Host name and port
</li>
<li>
KRPC address: The KRPC address of the <codeph>impalad</codeph>. Use this address
when you issue the <codeph>SHUTDOWN</codeph> command for this
<codeph>impalad</codeph>.
</li>
<li>
Whether acting as a coordinator
</li>
<li>
Whether acting as an executor
</li>
<li>
Quiescing status: Specify whether the graceful shutdown process has been initiated
on this <codeph>impalad</codeph>.
</li>
<li>
Memory limit for admission: The amount of memory that can be admitted to this
backend by the admission controller.
</li>
<li>
Memory reserved: The amount of memory reserved by queries that are active, either
currently executing or finished but not yet closed, on this backend.
<p>
The memory reserved for a query that is currently executing is its memory limit,
if set. Otherwise, if the query has no limit or if the query finished executing,
the current consumption is used.
</p>
</li>
<li>
Memory of the queries admitted to this coordinator: The memory submitted to this
particular host by the queries admitted by this coordinator.
</li>
</ul>
</conbody>
</concept>
<concept id="webui_impalad_catalog">
<title>Catalog Page</title>
<conbody>
<p>
The <b>Catalog</b> page of the <codeph>impalad</codeph> debug Web UI is at
<b>/catalog</b> under the main <codeph>impalad</codeph> Web UI.
</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. The primary debugging use case would be
to check if an <codeph>impalad</codeph> instance has knowledge of a particular table
that someone expects to be in a particular database.
</p>
</conbody>
</concept>
<concept id="webui_impalad_hadoop-varz">
<title>Hadoop Configuration</title>
<conbody>
<p>
The <b>Hadoop Configuration</b> page of the <codeph>impalad</codeph> debug Web UI is
at <b>/hadoop-varz</b> under the main <codeph>impalad</codeph> Web UI.
</p>
<p>
This page displays the Hadoop common configurations that Impala is running with.
</p>
</conbody>
</concept>
<concept id="webui_impalad_jmx">
<title>JMX</title>
<conbody>
<p>
The <b>JMX</b> page of the <codeph>impalad</codeph> debug Web UI is at <b>/jmx</b>
under the main <codeph>impalad</codeph> Web UI.
</p>
<p>
This page displays monitoring information about various JVM subsystems, such as memory
pools, thread management, runtime. etc.
</p>
</conbody>
</concept>
<concept id="webui_impalad_log_level">
<title>Java Log Level</title>
<conbody>
<p>
The <b>Change log level</b> page of the <codeph>impalad</codeph> debug Web UI is at
<b>/log_level</b> under the main <codeph>impalad</codeph> Web UI.
</p>
<p>
This page displays the current Java and backend log levels, and it allows you to
change the log levels dynamically without having to restart the
<codeph>impalad</codeph>.
</p>
</conbody>
</concept>
<concept id="webui_impalad_logs">
<title>Logs Page</title>
<conbody>
<p>
The <b>INFO logs</b> page of the <codeph>impalad</codeph> debug Web UI is at
<b>/logs</b> under the main <codeph>impalad</codeph> Web UI.
</p>
<p>
This page shows the last portion of the <codeph>impalad.INFO</codeph> log file,
including the info, warning, and error logs for the <cmdname>impalad</cmdname>. You
can see the details of the most recent operations, whether the operations succeeded or
encountered errors. This page provides one central place for the log files and saves
you from 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>
The <b>Memory Usage</b> page of the <codeph>impalad</codeph> debug Web UI is at
<b>/memz</b> under the main <codeph>impalad</codeph> Web UI.
</p>
<p>
This page displays the summary and detailed information about memory usage by the
<codeph>impalad</codeph>.
</p>
</conbody>
</concept>
<concept id="webui_impalad_metrics">
<title>Metrics Page</title>
<conbody>
<p>
The <b>Metrics</b> page of the <codeph>impalad</codeph> debug Web UI is at
<b>/metrics</b> under the main <codeph>impalad</codeph> Web UI.
</p>
<p>
This page displays the current set of metrics, counters and flags representing various
aspects of <codeph>impalad</codeph> internal operations.
</p>
</conbody>
</concept>
<concept id="webui_impalad_queries">
<title>Queries Page</title>
<conbody>
<p>
The <b>Queries</b> page of the <codeph>impalad</codeph> debug Web UI is at
<b>/queries</b> under the main <codeph>impalad</codeph> Web UI.
</p>
<p>
This page lists:
<ul>
<li>
Currently running queries
</li>
<li>
Queries that have completed their execution, but have not been closed yet
</li>
<li>
Completed queries whose details still reside in memory
</li>
</ul>
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>-&#8209;-&#8209;query_log_size</codeph>
and <codeph>-&#8209;-&#8209;query_log_size_in_bytes</codeph> startup options for
<codeph>impalad</codeph>.
</p>
<p>
This page provides:
<ul>
<li>
How many SQL statements are failing (<codeph>State</codeph> value of
<codeph>EXCEPTION</codeph>)
</li>
<li>
How large the result sets are (<codeph># rows fetched</codeph>)
</li>
<li>
How long each statement took (<codeph>Start Time</codeph> and <codeph>End
Time</codeph>)
</li>
</ul>
</p>
<p>
Click the <uicontrol>Details</uicontrol> link for a query to display the detailed
performance characteristics of that query, such as the profile output.
</p>
<p>
On the query detail page, in the <uicontrol>Profile</uicontrol> tab, you have options
to export the query profile output to the Thrift, text, or Json format.
</p>
<p>
The <b>Queries</b> page also includes the <b>Query Locations</b> section that lists
the number of running queries with fragments on this host.
</p>
</conbody>
</concept>
<concept id="webui_impalad_rpcz">
<title>RPC Services Page</title>
<conbody>
<p>
The <b>RPC durations</b> page of the <codeph>impalad</codeph> debug Web UI is at
<b>/rpcz</b> under the main <codeph>impalad</codeph> Web UI.
</p>
<p>
This page displays information, such as the duration, about the RPC communications of
this <codeph>impalad</codeph> with other Impala daemons.
</p>
</conbody>
</concept>
<concept id="webui_impalad_sessions">
<title>Sessions Page</title>
<conbody>
<p>
The <b>Sessions</b> page of the <codeph>impalad</codeph> debug Web UI is at
<b>/session</b> under the main <codeph>impalad</codeph> Web UI.
</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 <codeph>impala-shell</codeph> 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>
The <b>Threads</b> page of the <codeph>impalad</codeph> debug Web UI is at
<b>/threadz</b> under the main <codeph>impalad</codeph> Web UI.
</p>
<p>
This page displays information about the threads used by this instance of
<codeph>impalad</codeph>, and it 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>
The <b>Varz</b> page of the <codeph>impalad</codeph> debug Web UI is at <b>/varz</b>
under the main <codeph>impalad</codeph> Web UI.
</p>
<p>
This page shows the configuration settings in effect when this instance of
<codeph>impalad</codeph> communicates with other Hadoop components such as HDFS and
YARN. These settings are collected from a set of configuration files.
</p>
<p>
The bottom of this page also lists all the command-line settings in effect for this
instance of <codeph>impalad</codeph>. See
<xref
href="impala_config_options.xml#config_options"/> for information
about modifying these values.
</p>
</conbody>
</concept>
<concept id="webui_impalad_prometheus">
<title>Prometheus Metrics Page</title>
<conbody>
<p>At <b>/metrics_prometheus</b> under the main <codeph>impalad</codeph>
Web UI, the metrics are generated in Prometheus exposition format that
Prometheus can consume for event monitoring and alerting. The
<b>/metrics_prometheus</b> is not shown in the Web UI list of
pages.</p>
</conbody>
</concept>
</concept>
<concept id="webui_statestored">
<title>Debug Web UI for statestored</title>
<conbody>
<p>
To debug and troubleshoot the <codeph>statestored</codeph> daemon using a web-based
interface, open the URL
<codeph>http://<varname>impala&#8209;server&#8209;hostname</varname>:25010/</codeph> in
a browser. (For secure clusters, use the prefix <codeph>https://</codeph> instead of
<codeph>http://</codeph>.)
</p>
</conbody>
<concept id="webui_statestored_main">
<title>Main Page</title>
<conbody>
<p>
The main <codeph>statestored</codeph> Web UI page at <b>/</b> lists the following
information about the <codeph>statestored</codeph>:
</p>
<ul>
<li>
The version of the <codeph>statestored</codeph> daemon
</li>
<li>
Process start time
</li>
<li>
Hardware information
</li>
<li>
OS information
</li>
<li>
Process information
</li>
<li>
CGroup information
</li>
</ul>
</conbody>
</concept>
<concept id="webui_statestored_logs">
<title>Logs Page</title>
<conbody>
<p>
The <b>INFO logs</b> page of the debug Web UI is at <b>/logs</b> under the main
<codeph>statestored</codeph> Web UI.
</p>
<p>
This page shows the last portion of the <filepath>statestored.INFO</filepath> log
file, including the info, warning, and error logs for the
<codeph>statestored</codeph>. You can refer here to see the details of the most recent
operations, whether the operations succeeded or encountered errors. This page provides
one central place for the log files and saves you from 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_statestored_memz">
<title>Memz Page</title>
<conbody>
<p>
The <b>Memory Usage</b> page of the debug Web UI is at <b>/memz</b> under the main
<codeph>statestored</codeph> Web UI.
</p>
<p>
This page displays summary and detailed information about memory usage by the
<codeph>statestored</codeph>. 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>
The <b>Metrics</b> page of the debug Web UI is at <b>/metrics</b> under the main
<codeph>statestored</codeph> Web UI.
</p>
<p>
This page displays the current set of metrics: counters and flags representing various
aspects of <codeph>statestored</codeph> internal operation.
</p>
</conbody>
</concept>
<concept id="webui_statestored_rpcz">
<title>RPC Services Page</title>
<conbody>
<p>
The <b>RPC durations</b> page of the <codeph>statestored</codeph> debug Web UI is at
<b>/rpcz</b> under the main <codeph>statestored</codeph> Web UI.
</p>
<p>
This page displays information, such as the durations, about the RPC communications of
this <codeph>statestored</codeph> with other Impala daemons.
</p>
</conbody>
</concept>
<concept id="webui_statestored_subscribers">
<title>Subscribers Page</title>
<conbody>
<p>
The <b>Subscribers</b> page of the debug Web UI is at <b>/subscribers</b> under the
main <codeph>statestored</codeph> Web UI.
</p>
<p>
This page displays information about the other Impala daemons that have registered
with the <codeph>statestored</codeph> to receive and send updates.
</p>
</conbody>
</concept>
<concept id="webui_statestored_threadz">
<title>Threadz Page</title>
<conbody>
<p>
The <b>Threads</b> page of the debug Web UI is at <b>/threadz</b> under the main
<codeph>statestored</codeph> Web UI.
</p>
<p>
This page displays information about the threads used by this instance of
<codeph>statestored</codeph>, 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>
The <b>Topics</b> page of the debug Web UI is at <b>/topics</b> under the main
<codeph>statestored</codeph> Web UI.
</p>
<p>
This page displays information about the topics to which the other Impala daemons have
registered to receive updates.
</p>
</conbody>
</concept>
<concept id="webui_statestored_varz">
<title>Varz Page</title>
<conbody>
<p>
The <b>Varz</b> page of the debug Web UI is at <b>/varz</b> under the main
<codeph>statestored</codeph> Web UI.
</p>
<p>
This page shows the configuration settings in effect when this instance of
<codeph>statestored</codeph> communicates with other Hadoop components such as HDFS
and YARN. These settings are collected from a set of configuration files.
</p>
<p>
The bottom of this page also lists all the command-line settings in effect for this
instance of <codeph>statestored</codeph>. See
<xref
href="impala_config_options.xml#config_options"/> for information
about modifying these values.
</p>
</conbody>
</concept>
<concept id="webui_statestored_prometheus">
<title>Prometheus Metrics Page</title>
<conbody>
<p>At <b>/metrics_prometheus</b> under the main
<codeph>statestored</codeph> Web UI, the metrics are generated in
Prometheus exposition format that Prometheus can consume for event
monitoring and alerting. The <b>/metrics_prometheus</b> is not shown
in the Web UI list of pages.</p>
</conbody>
</concept>
</concept>
<concept id="webui_catalogd">
<title>Debug Web UI for catalogd</title>
<conbody>
<p> The main page of the debug Web UI is at
<codeph>http://<varname>impala&#8209;server&#8209;hostname</varname>:25020/</codeph>
(non-secure cluster) or
<codeph>https://<varname>impala&#8209;server&#8209;hostname</varname>:25020/</codeph>
(secure cluster). </p>
</conbody>
<concept id="webui_catalogd_main">
<title>Main Page</title>
<conbody>
<p> The main <codeph>catalogd</codeph> Web UI page at <b>/</b> lists the
following information about the <codeph>catalogd</codeph>: </p>
<ul>
<li> The version of the <codeph>catalogd</codeph> daemon </li>
<li> Process start time </li>
<li> Hardware information </li>
<li> OS information </li>
<li> Process information </li>
<li> CGroup information </li>
</ul>
</conbody>
</concept>
<concept id="webui_catalogd_catalog">
<title>Catalog Page</title>
<conbody>
<p> The <b>Catalog</b> page of the debug Web UI is at <b>/catalog</b>
under the main <codeph>catalogd</codeph> Web UI. </p>
<p> This page displays a list of databases and associated tables
recognized by this instance of <codeph>catalogd</codeph>. 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. The catalog information is represented as the
underlying Thrift data structures. </p>
</conbody>
</concept>
<concept id="webui_catalogd_jmx">
<title>JMX</title>
<conbody>
<p> The <b>JMX</b> page of the <codeph>catalogd</codeph> debug Web UI is
at <b>/jmx</b> under the main <codeph>catalogd</codeph> Web UI. </p>
<p> This page displays monitoring information about various JVM
subsystems, such as memory pools, thread management, runtime. etc.
</p>
</conbody>
</concept>
<concept id="webui_catalogd_log_level">
<title>Java Log Level</title>
<conbody>
<p> The <b>Change log level</b> page of the <codeph>catalogd</codeph>
debug Web UI is at <b>/log_level</b> under the main
<codeph>catalogd</codeph> Web UI. </p>
<p> The page displays the current Java and backend log levels and allows
you to change the log levels dynamically without having to restart the
<codeph>catalogd</codeph>
</p>
</conbody>
</concept>
<concept id="webui_catalogd_logs">
<title>Logs Page</title>
<conbody>
<p> The <b>INFO logs</b> page of the debug Web UI is at <b>/logs</b>
under the main <codeph>catalogd</codeph> Web UI. </p>
<p> This page shows the last portion of the
<codeph>catalogd.INFO</codeph> log file, including the info,
warning, and error logs for the <codeph>catalogd</codeph> daemon. You
can refer here to see the details of the most recent operations,
whether the operations succeeded or encountered errors. This page
provides one central place for the log files and saves you from
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_catalogd_memz">
<title>Memz Page</title>
<conbody>
<p> The <b>Memory Usage</b> page of the debug Web UI is at <b>/memz</b>
under the main <codeph>catalogd</codeph> Web UI. </p>
<p> This page displays summary and detailed information about memory
usage by the <codeph>catalogd</codeph>. 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_catalogd_metrics">
<title>Metrics Page</title>
<conbody>
<p> The <b>Metrics</b> page of the debug Web UI is at <b>/metrics</b>
under the main <codeph>catalogd</codeph> Web UI. </p>
<p> This page displays the current set of metrics: counters and flags
representing various aspects of <codeph>catalogd</codeph> internal
operation. </p>
<p/>
</conbody>
</concept>
<concept id="webui_catalogd_rpcz">
<title>RPC Services Page</title>
<conbody>
<p> The <b>RPC durations</b> page of the <codeph>catalogd</codeph> debug
Web UI is at <b>/rpcz</b> under the main <codeph>catalogd</codeph> Web
UI. </p>
<p> This page displays information, such as the durations, about the RPC
communications of this <codeph>catalogd</codeph> with other Impala
daemons. </p>
</conbody>
</concept>
<concept id="webui_catalogd_threadz">
<title>Threadz Page</title>
<conbody>
<p> The <b>Threads</b> page of the debug Web UI is at <b>/threadz</b>
under the main <codeph>catalogd</codeph> Web UI. </p>
<p> This page displays information about the threads used by this
instance of <codeph>catalogd</codeph>, 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_catalogd_varz">
<title>Varz Page</title>
<conbody>
<p> The <b>Varz</b> page of the debug Web UI is at <b>/varz</b> under
the main <codeph>catalogd</codeph> Web UI. </p>
<p> This page shows the configuration settings in effect when this
instance of <codeph>catalogd</codeph> communicates with other Hadoop
components such as HDFS and YARN. These settings are collected from a
set of configuration files. </p>
<p> The bottom of this page also lists all the command-line settings in
effect for this instance of <codeph>catalogd</codeph>. See <xref
href="impala_config_options.xml#config_options"/> for information
about modifying these values. </p>
</conbody>
</concept>
<concept id="webui_catalogd_prometheus">
<title>Prometheus Metrics Page</title>
<conbody>
<p>At <b>/metrics_prometheus</b> under the main
<codeph>catalogd</codeph> Web UI, the metrics are generated in
Prometheus exposition format that Prometheus can consume for event
monitoring and alerting. The <b>/metrics_prometheus</b> is not shown
in the Web UI list of pages.</p>
</conbody>
</concept>
</concept>
</concept>