TestHumongousAllocInitialMark.java

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/*
 * @test TestHumongousAllocInitialMark
 * @bug 7168848
 * @summary G1: humongous object allocations should initiate marking cycles when necessary
 * @library /testlibrary
 */

import com.oracle.java.testlibrary.*;

public class TestHumongousAllocInitialMark {
    private static final int heapSize                       = 200; // MB
    private static final int heapRegionSize                 = 1;   // MB
    private static final int initiatingHeapOccupancyPercent = 50;  // %

    public static void main(String[] args) throws Exception {
        ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(
            "-XX:+UseG1GC",
            "-Xms" + heapSize + "m",
            "-Xmx" + heapSize + "m",
            "-XX:G1HeapRegionSize=" + heapRegionSize + "m",
            "-XX:InitiatingHeapOccupancyPercent=" + initiatingHeapOccupancyPercent,
            "-XX:+PrintGC",
            HumongousObjectAllocator.class.getName());

        OutputAnalyzer output = new OutputAnalyzer(pb.start());
        output.shouldContain("GC pause (G1 Humongous Allocation) (young) (initial-mark)");
        output.shouldNotContain("Full GC");
        output.shouldHaveExitValue(0);
    }

    static class HumongousObjectAllocator {
        private static byte[] dummy;

        public static void main(String [] args) throws Exception {
            // Make object size 75% of region size
            final int humongousObjectSize =
                (int)(heapRegionSize * 1024 * 1024 * 0.75);

            // Number of objects to allocate to go above IHOP
            final int humongousObjectAllocations =
                (int)((heapSize * initiatingHeapOccupancyPercent / 100.0) / heapRegionSize) + 1;

            // Allocate
            for (int i = 1; i <= humongousObjectAllocations; i++) {
                System.out.println("Allocating humongous object " + i + "/" + humongousObjectAllocations +
                                   " of size " + humongousObjectSize + " bytes");
                dummy = new byte[humongousObjectSize];
            }
        }
    }
}