jdk-24/test/hotspot/jtreg/gc/arguments/TestSurvivorRatioFlag.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 */

package gc.arguments;

/*
 * @test TestSurvivorRatioFlag
 * @summary Verify that actual survivor ratio is equal to specified SurvivorRatio value
 * @requires vm.gc != "Z" & vm.gc != "Shenandoah"
 * @library /test/lib
 * @library /
 * @modules java.base/jdk.internal.misc
 *          java.management
 * @build jdk.test.whitebox.WhiteBox
 * @run driver jdk.test.lib.helpers.ClassFileInstaller jdk.test.whitebox.WhiteBox
 * @run driver gc.arguments.TestSurvivorRatioFlag
 */

import java.lang.management.MemoryUsage;
import java.util.Arrays;
import java.util.Collections;
import java.util.LinkedList;
import jdk.test.lib.process.OutputAnalyzer;
import jdk.test.lib.Utils;
import jdk.test.whitebox.WhiteBox;

public class TestSurvivorRatioFlag {

    public static final long M = 1024 * 1024;
    public static final long HEAP_SIZE = 200 * M;
    public static final long NEW_SIZE = 100 * M;

    public static void main(String args[]) throws Exception {
        LinkedList<String> options = new LinkedList<>(
                Arrays.asList(Utils.getFilteredTestJavaOpts("-XX:[^ ]*SurvivorRatio=[^ ]+"))
        );

        testSurvivorRatio(3, options);
        testSurvivorRatio(6, options);
        testSurvivorRatio(10, options);
        testSurvivorRatio(15, options);
        testSurvivorRatio(20, options);
    }

    /**
     * Verify that actual survivor ratio equal to specified.
     *
     * @param ratio survivor ratio that be verified
     * @param options additional options to JVM
     */
    public static void testSurvivorRatio(int ratio, LinkedList<String> options) throws Exception {

        LinkedList<String> vmOptions = new LinkedList<>(options);

        Collections.addAll(vmOptions,
                "-Xbootclasspath/a:.",
                "--add-exports=java.base/jdk.internal.misc=ALL-UNNAMED",
                "-XX:+UnlockDiagnosticVMOptions",
                "-XX:+WhiteBoxAPI",
                "-XX:MaxNewSize=" + NEW_SIZE,
                "-XX:NewSize=" + NEW_SIZE,
                "-Xmx" + HEAP_SIZE,
                "-Xms" + HEAP_SIZE,
                "-XX:SurvivorRatio=" + ratio,
                SurvivorRatioVerifier.class.getName(),
                Integer.toString(ratio)
        );

        OutputAnalyzer analyzer = GCArguments.executeLimitedTestJava(vmOptions);
        analyzer.shouldHaveExitValue(0);
    }

    /**
     * Class that verifies survivor ratio.
     */
    public static class SurvivorRatioVerifier {

        static WhiteBox wb = WhiteBox.getWhiteBox();

        public static final int MAX_ITERATIONS = 10;
        public static final int ARRAY_LENGTH = 10000;
        public static final int CHUNK_SIZE = 10000;

        public static void main(String args[]) throws Exception {
            if (args.length != 1) {
                throw new IllegalArgumentException("Expected 1 arg: <ratio>");
            }
            final int ratio = Integer.valueOf(args[0]);

            AllocationHelper allocator = new AllocationHelper(MAX_ITERATIONS, ARRAY_LENGTH, CHUNK_SIZE, () -> (verifySurvivorRatio(ratio)));
            allocator.allocateMemoryAndVerify();
        }

        /**
         * Verify that actual survivor ratio is equal to expected.
         * Depending on selected young GC we verify that:
         * - for DefNew and ParNew: eden_size / survivor_size is close to expectedRatio;
         * - for PSNew:             survivor_size equal to young_gen_size / expectedRatio;
         * - for G1:                survivor_regions <= young_list_length / expectedRatio.
         */
        public static Void verifySurvivorRatio(int expectedRatio) {
            GCTypes.YoungGCType type = GCTypes.YoungGCType.getYoungGCType();
            switch (type) {
                case DefNew:
                    verifyDefNewSurvivorRatio(expectedRatio);
                    break;
                case PSNew:
                    verifyPSSurvivorRatio(expectedRatio);
                    break;
                case G1:
                    verifyG1SurvivorRatio(expectedRatio);
                    break;
                default:
                    throw new RuntimeException("Unexpected young GC type");
            }
            return null;
        }

        private static void verifyDefNewSurvivorRatio(int expectedRatio) {
            MemoryUsage edenUsage = HeapRegionUsageTool.getEdenUsage();
            MemoryUsage survivorUsage = HeapRegionUsageTool.getSurvivorUsage();

            int actualRatio = (int) (edenUsage.getCommitted() / survivorUsage.getCommitted());
            if (Math.abs(actualRatio - expectedRatio) > 1) {
                throw new RuntimeException("Expected survivor ratio is: " + expectedRatio
                        + ", but observed ratio is: " + actualRatio);
            }
        }

        private static void verifyPSSurvivorRatio(int expectedRatio) {
            MemoryUsage edenUsage = HeapRegionUsageTool.getEdenUsage();
            MemoryUsage survivorUsage = HeapRegionUsageTool.getSurvivorUsage();

            long youngGenSize = edenUsage.getMax() + 2 * survivorUsage.getMax();
            // for Paralle GC Min/InitialSurvivorRatio = SurvivorRatio + 2
            long expectedSize = HeapRegionUsageTool.alignDown(youngGenSize / (expectedRatio + 2),
                    wb.psHeapGenerationAlignment());

            if (expectedSize != survivorUsage.getCommitted()) {
                throw new RuntimeException("Expected survivor size is: " + expectedSize
                        + ", but observed size is: " + survivorUsage.getCommitted());
            }
        }

        private static void verifyG1SurvivorRatio(int expectedRatio) {
            MemoryUsage survivorUsage = HeapRegionUsageTool.getSurvivorUsage();

            int regionSize = wb.g1RegionSize();
            int youngListLength = (int) Math.max(NEW_SIZE / regionSize, 1);
            int expectedSurvivorRegions = (int) Math.ceil(youngListLength / (double) expectedRatio);
            int observedSurvivorRegions = (int) (survivorUsage.getCommitted() / regionSize);

            if (expectedSurvivorRegions < observedSurvivorRegions) {
                throw new RuntimeException("Expected amount of G1 survivor regions is "
                        + expectedSurvivorRegions + ", but observed "
                        + observedSurvivorRegions);
            }
        }
    }
}