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23 
24 package gc.g1;
25 
26 /*
27  * @test TestEagerReclaimHumongousRegions
28  * @bug 8027959
29  * @summary Test to make sure that eager reclaim of humongous objects work. We simply try to fill
30  * up the heap with humongous objects that should be eagerly reclaimable to avoid Full GC.
31  * @requires vm.gc.G1
32  * @library /test/lib
33  * @modules java.base/jdk.internal.misc
34  *          java.management
35  * @run driver gc.g1.TestEagerReclaimHumongousRegions
36  */
37 
38 import java.util.regex.Pattern;
39 import java.util.regex.Matcher;
40 import java.util.LinkedList;
41 
42 import jdk.test.lib.process.OutputAnalyzer;
43 import jdk.test.lib.process.ProcessTools;
44 import jdk.test.lib.Asserts;
45 
46 class TestEagerReclaimHumongousRegionsReclaimRegionFast {
47     public static final int M = 1024*1024;
48 
49     public static LinkedList<Object> garbageList = new LinkedList<Object>();
50 
genGarbage()51     public static void genGarbage() {
52         for (int i = 0; i < 32*1024; i++) {
53             garbageList.add(new int[100]);
54         }
55         garbageList.clear();
56     }
57 
58     // A large object referenced by a static.
59     static int[] filler = new int[10 * M];
60 
main(String[] args)61     public static void main(String[] args) {
62 
63         int[] large = new int[M];
64 
65         Object ref_from_stack = large;
66 
67         for (int i = 0; i < 100; i++) {
68             // A large object that will be reclaimed eagerly.
69             large = new int[6*M];
70             genGarbage();
71             // Make sure that the compiler cannot completely remove
72             // the allocation of the large object until here.
73             System.out.println(large);
74         }
75 
76         // Keep the reference to the first object alive.
77         System.out.println(ref_from_stack);
78     }
79 }
80 
81 public class TestEagerReclaimHumongousRegions {
main(String[] args)82     public static void main(String[] args) throws Exception {
83         ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(
84             "-XX:+UseG1GC",
85             "-Xms128M",
86             "-Xmx128M",
87             "-Xmn16M",
88             "-Xlog:gc",
89             TestEagerReclaimHumongousRegionsReclaimRegionFast.class.getName());
90 
91         Pattern p = Pattern.compile("Full GC");
92 
93         OutputAnalyzer output = new OutputAnalyzer(pb.start());
94 
95         int found = 0;
96         Matcher m = p.matcher(output.getStdout());
97         while (m.find()) { found++; }
98         System.out.println("Issued " + found + " Full GCs");
99         Asserts.assertLT(found, 10, "Found that " + found + " Full GCs were issued. This is larger than the bound. Eager reclaim seems to not work at all");
100 
101         output.shouldHaveExitValue(0);
102     }
103 }
104