1 /*
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3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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23 
24 package gc;
25 
26 /* @test
27  * @bug 8240696
28  * @library /test/lib
29  * @build sun.hotspot.WhiteBox
30  * @modules java.base
31  * @run main ClassFileInstaller sun.hotspot.WhiteBox
32  * @run main/othervm
33  *      -Xbootclasspath/a:.
34  *      -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI
35  *      gc.TestReferenceClearDuringMarking
36  */
37 
38 import java.lang.ref.WeakReference;
39 import sun.hotspot.WhiteBox;
40 
41 public class TestReferenceClearDuringMarking {
42     private static final WhiteBox WB = WhiteBox.getWhiteBox();
43 
44     private static Object testA = new Object();
45     private static Object testB = new Object();
46 
47     private static final WeakReference<Object> refA1 = new WeakReference<Object>(testA);
48     private static final WeakReference<Object> refA2 = new WeakReference<Object>(testA);
49 
50     private static final WeakReference<Object> refB1 = new WeakReference<Object>(testB);
51     private static final WeakReference<Object> refB2 = new WeakReference<Object>(testB);
52 
test()53     private static void test() {
54         while (!WB.isObjectInOldGen(testA) ||
55                !WB.isObjectInOldGen(testB) ||
56                !WB.isObjectInOldGen(refA1) ||
57                !WB.isObjectInOldGen(refA2) ||
58                !WB.isObjectInOldGen(refB1) ||
59                !WB.isObjectInOldGen(refB2)) {
60             WB.fullGC();
61         }
62 
63         WB.concurrentGCAcquireControl();
64         try {
65             testA = null;
66             testB = null;
67 
68             WB.concurrentGCRunTo(WB.AFTER_MARKING_STARTED);
69             // Clear A1 early in marking, before reference discovery.
70             refA1.clear();
71 
72             WB.concurrentGCRunTo(WB.BEFORE_MARKING_COMPLETED);
73             // Clear B1 late in marking, after reference discovery.
74             refB1.clear();
75 
76             WB.concurrentGCRunToIdle();
77 
78             // Verify that A2 and B2 still cleared by GC, i.e. the preceding
79             // clear operations did not extend the lifetime of the referents.
80             if (!refA2.refersTo(null)) {
81                 throw new RuntimeException("refA2 not cleared");
82             }
83             if (!refB2.refersTo(null)) {
84                 throw new RuntimeException("refB2 not cleared");
85             }
86         } finally {
87             WB.concurrentGCReleaseControl();
88         }
89     }
90 
main(String[] args)91     public static void main(String[] args) {
92         if (WB.supportsConcurrentGCBreakpoints()) {
93             test();
94         }
95     }
96 }
97