test/hotspot/jtreg/gc/g1/TestSkipRebuildRemsetPhase.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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package gc.g1;

/*
 * @test TestSkipRebuildRemsetPhase
 * @summary Skip Rebuild Remset Phase if the Remark pause does not identify any rebuild candidates.
 *          Fill up a region to above the set G1MixedGCLiveThresholdPercent.
 * @requires vm.gc.G1
 * @library /test/lib
 * @build jdk.test.whitebox.WhiteBox
 * @run driver jdk.test.lib.helpers.ClassFileInstaller jdk.test.whitebox.WhiteBox
 * @run driver gc.g1.TestSkipRebuildRemsetPhase
 */

import jdk.test.lib.process.OutputAnalyzer;
import jdk.test.lib.process.ProcessTools;
import jdk.test.whitebox.WhiteBox;

public class TestSkipRebuildRemsetPhase {
    public static void main(String[] args) throws Exception {
        OutputAnalyzer output = ProcessTools.executeLimitedTestJava("-Xbootclasspath/a:.",
                                                                    "-XX:+UseG1GC",
                                                                    "-XX:+UnlockExperimentalVMOptions",
                                                                    "-XX:+UnlockDiagnosticVMOptions",
                                                                    "-XX:+WhiteBoxAPI",
                                                                    "-XX:G1MixedGCLiveThresholdPercent=20",
                                                                    "-Xlog:gc+marking=debug,gc+phases=debug,gc+remset+tracking=trace",
                                                                    "-Xms10M",
                                                                    "-Xmx10M",
                                                                    GCTest.class.getName());
        output.shouldContain("Skipping Remembered Set Rebuild.");
        output.shouldContain("No Remembered Sets to update after rebuild");
        output.shouldHaveExitValue(0);
    }

    public static class GCTest {
        public static void main(String args[]) throws Exception {
            WhiteBox wb = WhiteBox.getWhiteBox();
            // Allocate some memory less than region size.
            Object used = alloc();

            // Trigger the full GC using the WhiteBox API.
            wb.fullGC();  // full

            // Memory objects have been promoted to old by full GC.
            // Concurrent cycle should not select any regions for rebuilding
            wb.g1RunConcurrentGC();
            System.out.println(used);
        }

        private static Object alloc() {
            // Since G1MixedGCLiveThresholdPercent is 20%, make sure to allocate object larger than that
            // so that it will not be collected and the expected message printed.
            final int objectSize = WhiteBox.getWhiteBox().g1RegionSize() / 3;
            Object ret = new byte[objectSize];
            return ret;
        }
    }
}