test/jdk/java/lang/String/CompactString/NegativeSize.java

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import java.io.IOException;
import java.nio.charset.StandardCharsets;

/*
 * @test
 * @bug 8077559
 * @summary Tests Compact String for negative size.
 * @requires vm.bits == 64 & os.maxMemory >= 4G
 * @run main/othervm -XX:+CompactStrings -Xmx4g NegativeSize
 * @run main/othervm -XX:-CompactStrings -Xmx4g NegativeSize
 */

// In Java8: java.lang.OutOfMemoryError: Java heap space
// In Java9+: was java.lang.NegativeArraySizeException: -1894967266
public class NegativeSize {

    static byte[] generateData() {
        int asciisize = 1_200_000_000;
        byte[] nonAscii = "非アスキー".getBytes();
        int nonAsciiSize = nonAscii.length;
        // 1 GB
        byte[] arr = new byte[asciisize + nonAsciiSize];
        for (int i=0; i<asciisize; ++i) {
            arr[i] = (byte)('0' + (i % 40));
        }
        for(int i=0; i<nonAsciiSize; ++i) {
            arr[i + asciisize] = nonAscii[i];
        }
        return arr;
    }


    public static void main(String[] args) throws IOException {

        try {
            byte[] largeBytes = generateData();
            String inStr = new String(largeBytes, StandardCharsets.UTF_8);
            System.out.println(inStr.length());
            System.out.println(inStr.substring(1_200_000_000));
        } catch (OutOfMemoryError ex) {
            if (ex.getMessage().startsWith("UTF16 String size is")) {
                System.out.println("Succeeded with OutOfMemoryError");
            } else {
                throw new RuntimeException("Failed: Not the OutOfMemoryError expected", ex);
            }
        } catch (NegativeArraySizeException ex) {
            throw new RuntimeException("Failed: Expected OutOfMemoryError", ex);
        }
    }
}