HDFS-10534. NameNode WebUI should display DataNode usage histogram. Contributed by Kai Sasaki.

hadoop-hdfs-project/hadoop-hdfs/pom.xml

@@ -402,6 +402,7 @@ http://maven.apache.org/xsd/maven-4.0.0.xsd">
             <exclude>src/main/webapps/static/json-bignum.js</exclude>
             <exclude>src/main/webapps/static/dataTables.bootstrap.css</exclude>
             <exclude>src/main/webapps/static/dataTables.bootstrap.js</exclude>
+            <exclude>src/main/webapps/static/d3-v4.1.1.min.js</exclude>
             <exclude>src/test/resources/diskBalancer/data-cluster-3node-3disk.json</exclude>
           </excludes>
         </configuration>

hadoop-hdfs-project/hadoop-hdfs/src/main/webapps/hdfs/dfshealth.html

@@ -299,6 +299,8 @@
     <li class="dfshealth-node-icon dfshealth-node-down-maintenance">In Maintenance &amp; dead</li>
   </ul>
 </div>
+<div class="page-header"><h1><small>Datanode usage histogram</small></h1></div>
+<small><div id="datanode-usage-histogram"></div></small>
 <div class="page-header"><h1><small>In operation</small></h1></div>
 <small>
 <table class="table" id="table-datanodes">
@@ -467,6 +469,7 @@ There are no reported volume failures.
 </script><script type="text/javascript" src="/static/dust-full-2.0.0.min.js">
 </script><script type="text/javascript" src="/static/dust-helpers-1.1.1.min.js">
 </script><script type="text/javascript" src="/static/dfs-dust.js">
+</script><script type="text/javascript" src="/static/d3-v4.1.1.min.js">
 </script><script type="text/javascript" src="dfshealth.js">
 </script>
 </body>

hadoop-hdfs-project/hadoop-hdfs/src/main/webapps/hdfs/dfshealth.js

@@ -255,6 +255,70 @@
       return r;
     }
 
+    function renderHistogram(dnData) {
+      var data = dnData.LiveNodes.map(function(dn) {
+        return (dn.usedSpace / dn.capacity) * 100.0;
+      });
+
+      var formatCount = d3.format(",.0f");
+
+      var widthCap = $("div.container").width();
+      var heightCap = 150;
+
+      var margin = {top: 10, right: 60, bottom: 30, left: 30},
+          width = widthCap * 0.9,
+          height = heightCap - margin.top - margin.bottom;
+
+      var x = d3.scaleLinear()
+          .domain([0.0, 100.0])
+          .range([0, width]);
+
+      var bins = d3.histogram()
+          .domain(x.domain())
+          .thresholds(x.ticks(20))
+          (data);
+
+      var y = d3.scaleLinear()
+          .domain([0, d3.max(bins, function(d) { return d.length; })])
+          .range([height, 0]);
+
+      var svg = d3.select("#datanode-usage-histogram").append("svg")
+          .attr("width", width + 50.0)
+          .attr("height", height + margin.top + margin.bottom)
+          .append("g")
+          .attr("transform", "translate(" + margin.left + "," + margin.top + ")");
+
+      svg.append("text")
+          .attr("x", (width / 2))
+          .attr("y", heightCap - 6 - (margin.top / 2))
+          .attr("text-anchor", "middle")
+          .style("font-size", "15px")
+          .text("Disk usage of each DataNode (%)");
+
+      var bar = svg.selectAll(".bar")
+          .data(bins)
+          .enter().append("g")
+          .attr("class", "bar")
+          .attr("transform", function(d) { return "translate(" + x(d.x0) + "," + y(d.length) + ")"; });
+
+      bar.append("rect")
+          .attr("x", 1)
+          .attr("width", x(bins[0].x1) - x(bins[0].x0) - 1)
+          .attr("height", function(d) { return height - y(d.length); });
+
+      bar.append("text")
+          .attr("dy", ".75em")
+          .attr("y", 6)
+          .attr("x", (x(bins[0].x1) - x(bins[0].x0)) / 2)
+          .attr("text-anchor", "middle")
+          .text(function(d) { return formatCount(d.length); });
+
+      svg.append("g")
+          .attr("class", "axis axis--x")
+          .attr("transform", "translate(0," + height + ")")
+          .call(d3.axisBottom(x));
+    }
+
     $.get(
       '/jmx?qry=Hadoop:service=NameNode,name=NameNodeInfo',
       guard_with_startup_progress(function (resp) {
@@ -273,6 +337,7 @@
               { 'orderDataType': 'ng-value', 'type': 'numeric'},
               { 'orderData': 5 }
             ]});
+          renderHistogram(data);
           $('#ui-tabs a[href="#tab-datanode"]').tab('show');
         });
       })).error(ajax_error_handler);

hadoop-hdfs-project/hadoop-hdfs/src/main/webapps/static/hadoop.css

@@ -292,4 +292,13 @@ header.bs-docs-nav, header.bs-docs-nav .navbar-brand {
   min-width: 75px;
   float: right;
   left: 75px;
+}
+
+.bar rect {
+    fill: #5FA33F;
+}
+
+.bar text {
+    fill: #fff;
+    font: 10px sans-serif;
 }