[fix] [broker] consider iowait as idle. (#19110)

pulsar-broker/src/main/java/org/apache/pulsar/broker/loadbalance/LinuxInfoUtils.java

@@ -161,7 +161,8 @@ public static long getCpuUsageForCGroup() {
      * </pre>
      * <p>
      * Line is split in "words", filtering the first. The sum of all numbers give the amount of cpu cycles used this
-     * far. Real CPU usage should equal the sum subtracting the idle cycles, this would include iowait, irq and steal.
+     * far. Real CPU usage should equal the sum substracting the idle cycles(that is idle+iowait), this would include
+     * cpu, user, nice, system, irq, softirq, steal, guest and guest_nice.
      */
     public static ResourceUsage getCpuUsageForEntireHost() {
         try (Stream<String> stream = Files.lines(Paths.get(PROC_STAT_PATH))) {
@@ -175,7 +176,7 @@ public static ResourceUsage getCpuUsageForEntireHost() {
                     .filter(s -> !s.contains("cpu"))
                     .mapToLong(Long::parseLong)
                     .sum();
-            long idle = Long.parseLong(words[4]);
+            long idle = Long.parseLong(words[4]) + Long.parseLong(words[5]);
             return ResourceUsage.builder()
                     .usage(total - idle)
                     .idle(idle)

pulsar-broker/src/main/java/org/apache/pulsar/broker/loadbalance/impl/LinuxBrokerHostUsageImpl.java

@@ -155,7 +155,8 @@ private double getTotalCpuUsageForCGroup(double elapsedTimeSeconds) {
      * </pre>
      *
      * Line is split in "words", filtering the first. The sum of all numbers give the amount of cpu cycles used this
-     * far. Real CPU usage should equal the sum subtracting the idle cycles, this would include iowait, irq and steal.
+     * far. Real CPU usage should equal the sum substracting the idle cycles(that is idle+iowait), this would include
+     * cpu, user, nice, system, irq, softirq, steal, guest and guest_nice.
      */
     private double getTotalCpuUsageForEntireHost() {
         LinuxInfoUtils.ResourceUsage cpuUsageForEntireHost = getCpuUsageForEntireHost();

pulsar-broker/src/test/java/org/apache/pulsar/broker/loadbalance/LinuxInfoUtilsTest.java

@@ -0,0 +1,50 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.pulsar.broker.loadbalance;
+
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.mockStatic;
+import static org.testng.Assert.assertEquals;
+import java.nio.file.Files;
+import java.util.stream.Stream;
+import lombok.extern.slf4j.Slf4j;
+import org.mockito.MockedStatic;
+import org.testng.annotations.Test;
+
+@Slf4j
+@Test(groups = "broker")
+public class LinuxInfoUtilsTest {
+
+    /**
+     * simulate reading first line of /proc/stat to get total cpu usage.
+     */
+    @Test
+    public void testGetCpuUsageForEntireHost(){
+        try (MockedStatic<Files> filesMockedStatic = mockStatic(Files.class)) {
+            filesMockedStatic.when(() -> Files.lines(any())).thenReturn(
+                    Stream.generate(() -> "cpu  317808 128  58637  2503692 7634   0   13472   0    0     0"));
+            long idle = 2503692 + 7634, total = 2901371;
+            LinuxInfoUtils.ResourceUsage resourceUsage = LinuxInfoUtils.ResourceUsage.builder()
+                    .usage(total - idle)
+                    .idle(idle)
+                    .total(total).build();
+            assertEquals(LinuxInfoUtils.getCpuUsageForEntireHost(), resourceUsage);
+        }
+    }
+}