zhengruifeng commented on a change in pull request #25349:
[SPARK-28538][UI][WIP] Document SQL page
URL: https://github.com/apache/spark/pull/25349#discussion_r311332004
##########
File path: docs/monitoring.md
##########
@@ -40,6 +40,100 @@ To view the web UI after the fact, set
`spark.eventLog.enabled` to true before s
application. This configures Spark to log Spark events that encode the
information displayed
in the UI to persisted storage.
+## Web UI Tabs
+The web UI provides an overview of the Spark cluster and is composed of
following tabs:
+
+### Jobs Tab
+The Jobs tab displays a summary page of all jobs in the Spark application and
a detailed page
+for each job. The summary page shows high-level information, such as the
status, duration, and
+progress of all jobs and the overall event timeline. When you click on a job
on the summary
+page, you see the detailed page for that job. The detailed page further shows
the event timeline,
+DAG visualization, and all stages of the job.
+
+### Stages Tab
+The Stages tab displays a summary page that shows the current state of all
stages of all jobs in
+the Spark application, and, when you click on a stage, a detailed page for
that stage. The details
+page shows the event timeline, DAG visualization, and all tasks for the stage.
+
+### Storage Tab
+The Storage tab displays the persisted RDDs, if any, in the application. The
summary page shows
+the storage levels, sizes and partitions of all RDDs, and the detailed page
shows the sizes and
+using executors for all partitions in an RDD.
+
+### Environment Tab
+The Environment tab displays the values for the different environment and
configuration variables,
+including JVM, Spark, and system properties.
+
+### Executors Tab
+The Executors tab displays summary information about the executors that were
created for the
+application, including memory and disk usage and task and shuffle information.
The Storage Memory
+column shows the amount of memory used and reserved for caching data.
+
+### SQL Tab
+If the application executes Spark SQL queries, the SQL tab displays
information, such as the duration,
+jobs, and physical and logical plans for the queries. Here we include a basic
example to illustrate
+this tab:
+{% highlight scala %}
+scala> val df = Seq((1, "andy"), (2, "bob"), (2, "andy")).toDF("count", "name")
+df: org.apache.spark.sql.DataFrame = [count: int, name: string]
+
+scala> df.count
+res0: Long = 3
+
+scala> df.createGlobalTempView("df")
+
+scala> spark.sql("select name,sum(count) from global_temp.df group by
name").show
++----+----------+
+|name|sum(count)|
++----+----------+
+|andy| 3|
+| bob| 2|
++----+----------+
+{% endhighlight %}
+
+<p style="text-align: center;">
+ <img src="img/webui-sql-tab.png"
+ title="SQL tab"
+ alt="SQL tab"
+ width="80%" />
+ <!-- Images are downsized intentionally to improve quality on retina
displays -->
+</p>
+
+Now the above three dataframe/SQL operators are shown in the list. If we click
the
+'show at \<console\>: 24' link of the last query, we will see the DAG of the
job.
+
+<p style="text-align: center;">
+ <img src="img/webui-sql-dag.png"
+ title="SQL DAG"
+ alt="SQL DAG"
+ width="50%" />
+ <!-- Images are downsized intentionally to improve quality on retina
displays -->
+</p>
+
+We can see that detailed information of each stage. The first block
'WholeStageCodegen'
+compile multiple operator ('LocalTableScan' and 'HashAggregate') together into
a single Java
+function to improve performance, and metrics like number of rows and spill
size are listed in
+the block. The second block 'Exchange' shows the metrics on the shuffle
exchange, including
+number of written shuffle records, total data size, etc.
+
+
+<p style="text-align: center;">
+ <img src="img/webui-sql-plan.png"
Review comment:
HI, @dongjoon-hyun I local run the example and make screenshots to png
files.
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