BigReadWrite.java

/*
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
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 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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/* @test
 * @requires os.family == "Linux"
 * @bug 4863423
 * @summary Test Util caching policy
 */

import java.io.*;
import java.nio.*;
import java.nio.channels.*;

public class BigReadWrite {

    static int testSize = 15;

    public static void main(String[] args) throws Exception {
        FileOutputStream fos = new FileOutputStream("/dev/zero");
        FileChannel fc = fos.getChannel();

        // Three small writes to fill up the Util cache
        ByteBuffer buf = ByteBuffer.allocate(900);
        fc.write(buf);
        buf = ByteBuffer.allocate(950);
        fc.write(buf);
        buf = ByteBuffer.allocate(975);
        fc.write(buf);
        buf = ByteBuffer.allocate(4419000);

        // Now initiate large write to create larger direct buffers
        long iterations = 0;
        while (iterations < 50) {
            fc.write(buf);
            buf.rewind();
            iterations++;
        }
        // Clean up
        fc.close();
    }
}