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23 
24 /*
25  * @test TestEagerReclaimHumongousRegionsClearMarkBits
26  * @bug 8051973
27  * @summary Test to make sure that eager reclaim of humongous objects correctly clears
28  * mark bitmaps at reclaim.
29  * @key gc
30  * @library /testlibrary
31  */
32 
33 import java.util.ArrayList;
34 import java.util.LinkedList;
35 import java.util.Random;
36 
37 import com.oracle.java.testlibrary.OutputAnalyzer;
38 import com.oracle.java.testlibrary.ProcessTools;
39 
40 // An object that has a few references to other instances to slow down marking.
41 class ObjectWithSomeRefs {
42     public ObjectWithSomeRefs other1;
43     public ObjectWithSomeRefs other2;
44     public ObjectWithSomeRefs other3;
45     public ObjectWithSomeRefs other4;
46 }
47 
48 class ReclaimRegionFast {
49     public static final long MAX_MILLIS_FOR_RUN = 50 * 1000; // The maximum runtime for the actual test.
50 
51     public static final int M = 1024*1024;
52 
53     public static LinkedList<Object> garbageList = new LinkedList<Object>();
54 
genGarbage(Object large)55     public static void genGarbage(Object large) {
56         for (int i = 0; i < 64*1024; i++) {
57             Object[] garbage = new Object[50];
58             garbage[0] = large;
59             garbageList.add(garbage);
60         }
61         garbageList.clear();
62     }
63 
64     public static ArrayList<ObjectWithSomeRefs> longList = new ArrayList<ObjectWithSomeRefs>();
65 
main(String[] args)66     public static void main(String[] args) {
67 
68         for (int i = 0; i < 16*1024; i++) {
69              longList.add(new ObjectWithSomeRefs());
70         }
71 
72         Random rnd = new Random();
73         for (int i = 0; i < longList.size(); i++) {
74              int len = longList.size();
75              longList.get(i).other1 = longList.get(rnd.nextInt(len));
76              longList.get(i).other2 = longList.get(rnd.nextInt(len));
77              longList.get(i).other3 = longList.get(rnd.nextInt(len));
78              longList.get(i).other4 = longList.get(rnd.nextInt(len));
79         }
80 
81         int[] large1 = new int[M];
82         int[] large2 = null;
83         int[] large3 = null;
84         int[] large4 = null;
85 
86         Object ref_from_stack = large1;
87 
88         long start_millis = System.currentTimeMillis();
89 
90         for (int i = 0; i < 20; i++) {
91             long current_millis = System.currentTimeMillis();
92             if ((current_millis - start_millis) > MAX_MILLIS_FOR_RUN) {
93               System.out.println("Finishing test because maximum runtime exceeded");
94               break;
95             }
96             // A set of large objects that will be reclaimed eagerly - and hopefully marked.
97             large1 = new int[M - 20];
98             large2 = new int[M - 20];
99             large3 = new int[M - 20];
100             large4 = new int[M - 20];
101             genGarbage(large1);
102             // Make sure that the compiler cannot completely remove
103             // the allocation of the large object until here.
104             System.out.println(large1 + " " + large2 + " " + large3 + " " + large4);
105         }
106 
107         // Keep the reference to the first object alive.
108         System.out.println(ref_from_stack);
109     }
110 }
111 
112 public class TestEagerReclaimHumongousRegionsClearMarkBits {
main(String[] args)113     public static void main(String[] args) throws Exception {
114         ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(
115             "-XX:+UseG1GC",
116             "-Xms128M",
117             "-Xmx128M",
118             "-Xmn2M",
119             "-XX:G1HeapRegionSize=1M",
120             "-XX:InitiatingHeapOccupancyPercent=0", // Want to have as much as possible initial marks.
121             "-XX:+PrintGC",
122             "-XX:+VerifyAfterGC",
123             "-XX:ConcGCThreads=1", // Want to make marking as slow as possible.
124             "-XX:+IgnoreUnrecognizedVMOptions", // G1VerifyBitmaps is develop only.
125             "-XX:+G1VerifyBitmaps",
126             ReclaimRegionFast.class.getName());
127         OutputAnalyzer output = new OutputAnalyzer(pb.start());
128         output.shouldHaveExitValue(0);
129     }
130 }
131 
132