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13  * accompanied this code).
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23 
24 /*
25  * @test
26  * @bug     4982301
27  * @summary Sanity Test for GarbageCollectorMXBean.getLastGcInfo().
28  * @author  Mandy Chung
29  *
30  * @run main/othervm -XX:-ExplicitGCInvokesConcurrent LastGCInfo
31  */
32 // Passing "-XX:-ExplicitGCInvokesConcurrent" to force System.gc()
33 // run on foreground when CMS is used and prevent situations when "GcInfo"
34 // is missing even though System.gc() was successfuly processed.
35 
36 import java.lang.management.ManagementFactory;
37 import java.lang.management.MemoryUsage;
38 import java.lang.management.MemoryPoolMXBean;
39 import java.util.*;
40 import com.sun.management.GcInfo;
41 import com.sun.management.GarbageCollectorMXBean;
42 
43 public class LastGCInfo {
main(String[] argv)44     public static void main(String[] argv) throws Exception {
45         boolean hasGcInfo = false;
46 
47         System.gc();
48         List mgrs = ManagementFactory.getGarbageCollectorMXBeans();
49         for (ListIterator iter = mgrs.listIterator(); iter.hasNext(); ) {
50             Object mgr = iter.next();
51             if (mgr instanceof GarbageCollectorMXBean) {
52                 GarbageCollectorMXBean gc = (GarbageCollectorMXBean) mgr;
53                 GcInfo info = gc.getLastGcInfo();
54                 if (info != null) {
55                     checkGcInfo(gc.getName(), info);
56                     hasGcInfo = true;
57                 }
58             }
59         }
60 
61         if (! hasGcInfo) {
62             throw new RuntimeException("No GcInfo returned");
63         }
64         System.out.println("Test passed.");
65     }
66 
checkGcInfo(String name, GcInfo info)67     private static void checkGcInfo(String name, GcInfo info) throws Exception {
68         System.out.println("GC statistic for : " + name);
69         System.out.print("GC #" + info.getId());
70         System.out.print(" start:" + info.getStartTime());
71         System.out.print(" end:" + info.getEndTime());
72         System.out.println(" (" + info.getDuration() + "ms)");
73         Map usage = info.getMemoryUsageBeforeGc();
74 
75         List pnames = new ArrayList();
76         for (Iterator iter = usage.entrySet().iterator(); iter.hasNext(); ) {
77             Map.Entry entry = (Map.Entry) iter.next();
78             String poolname = (String) entry.getKey();
79             pnames.add(poolname);
80             MemoryUsage busage = (MemoryUsage) entry.getValue();
81             MemoryUsage ausage = (MemoryUsage) info.getMemoryUsageAfterGc().get(poolname);
82             if (ausage == null) {
83                 throw new RuntimeException("After Gc Memory does not exist" +
84                     " for " + poolname);
85             }
86             System.out.println("Usage for pool " + poolname);
87             System.out.println("   Before GC: " + busage);
88             System.out.println("   After GC: " + ausage);
89         }
90 
91         // check if memory usage for all memory pools are returned
92         List pools = ManagementFactory.getMemoryPoolMXBeans();
93         for (Iterator iter = pools.iterator(); iter.hasNext(); ) {
94             MemoryPoolMXBean p = (MemoryPoolMXBean) iter.next();
95             if (!pnames.contains(p.getName())) {
96                 throw new RuntimeException("GcInfo does not contain " +
97                     "memory usage for pool " + p.getName());
98             }
99         }
100     }
101 }
102