Java GraphLayout类代码示例

import org.openjdk.jol.info.GraphLayout; //导入依赖的package包/类
public static void main(String[] args) throws Exception {
    out.println(VM.current().details());

    ArrayList<Integer> al = new ArrayList<Integer>();
    LinkedList<Integer> ll = new LinkedList<Integer>();

    for (int i = 0; i < 1000; i++) {
        Integer io = i; // box once
        al.add(io);
        ll.add(io);
    }

    al.trimToSize();

    PrintWriter pw = new PrintWriter(out);
    pw.println(GraphLayout.parseInstance(al).toFootprint());
    pw.println(GraphLayout.parseInstance(ll).toFootprint());
    pw.println(GraphLayout.parseInstance(al, ll).toFootprint());
    pw.close();
}
 

import org.openjdk.jol.info.GraphLayout; //导入依赖的package包/类
public static void main(String[] args) throws Exception {
    out.println(VM.current().details());

    // allocate some objects to beef up generations
    for (int c = 0; c < 1000000; c++) {
        sink = new Object();
    }
    System.gc();

    List<String> list = new ArrayList<String>();
    for (int c = 0; c < 1000; c++) {
        list.add("Key" + c);
    }

    for (int c = 1; c <= 10; c++) {
        GraphLayout.parseInstance(list).toImage("list-" + c + ".png");
        System.gc();
    }
}
 

import org.openjdk.jol.info.GraphLayout; //导入依赖的package包/类
public static void main(String[] args) throws Exception {
    out.println(VM.current().details());

    // allocate some objects to beef up generations
    for (int c = 0; c < 1000000; c++) {
        sink = new Object();
    }
    System.gc();

    final int COUNT = 10000;

    Object[] array = new Object[COUNT];
    for (int c = 0; c < COUNT; c++) {
        array[c] = new Object();
    }

    Object obj = array;

    GraphLayout.parseInstance(obj).toImage("array-1-new.png");

    for (int c = 2; c <= 5; c++) {
        System.gc();
        GraphLayout.parseInstance(obj).toImage("array-" + c + "-before.png");
    }

    for (int c = 0; c < COUNT; c++) {
        if (Math.random() < 0.5) {
            array[c] = null;
        }
    }

    GraphLayout.parseInstance(obj).toImage("array-6-after.png");

    for (int c = 7; c <= 10; c++) {
        System.gc();
        GraphLayout.parseInstance(obj).toImage("array-" + c + "-after-gc.png");
    }
}
 

import org.openjdk.jol.info.GraphLayout; //导入依赖的package包/类
public static void main(String[] args) throws Exception {
    out.println(VM.current().details());

    // allocate some objects to beef up generations
    for (int c = 0; c < 1000000; c++) {
        sink = new Object();
    }
    System.gc();

    final int COUNT = 1000;

    ConcurrentHashMap<Object, Object> chm = new ConcurrentHashMap<Object, Object>();

    addElements(COUNT, chm);

    GraphLayout.parseInstance(chm).toImage("chm-1-new.png");

    for (int c = 2; c <= 5; c++) {
        GraphLayout.parseInstance(chm).toImage("chm-" + c + "-gc.png");
        System.gc();
    }

    addElements(COUNT, chm);

    for (int c = 6; c <= 10; c++) {
        GraphLayout.parseInstance(chm).toImage("chm-" + c + "-more-gc.png");
        System.gc();
    }

}
 

import org.openjdk.jol.info.GraphLayout; //导入依赖的package包/类
public static void main(String[] args) throws Exception {
    out.println(VM.current().details());

    PrintWriter pw = new PrintWriter(System.out, true);

    Map<Dummy, Void> map = new HashMap<Dummy, Void>();

    map.put(new Dummy(1), null);
    map.put(new Dummy(2), null);

    System.gc();
    pw.println(GraphLayout.parseInstance(map).toPrintable());

    map.put(new Dummy(2), null);
    map.put(new Dummy(2), null);
    map.put(new Dummy(2), null);
    map.put(new Dummy(2), null);

    System.gc();
    pw.println(GraphLayout.parseInstance(map).toPrintable());

    for (int c = 0; c < 12; c++) {
        map.put(new Dummy(2), null);
    }

    System.gc();
    pw.println(GraphLayout.parseInstance(map).toPrintable());

    pw.close();
}
 

import org.openjdk.jol.info.GraphLayout; //导入依赖的package包/类
public static void printSize(final @NotNull Object object) {
    System.out.println(String.format("%-30s(%-25s)\t %-10s\t%-10s\t%-10s\n",
            object.toString(),
            object.getClass(),
            SimpleAgent.getObjectSize(object),
            ObjectLayer.layout(object).instanceSize(),
            GraphLayout.parseInstance(object).totalSize()
    ));
}
 

import org.openjdk.jol.info.GraphLayout; //导入依赖的package包/类
public static void main(String[] args) {
  new Container().printMe();

  System.out.println(VMSupport.vmDetails());
  System.out.println(ClassLayout.parseClass(Container.class).toPrintable());
  System.out.println(GraphLayout.parseInstance(new Container()).toPrintable());

}
 

import org.openjdk.jol.info.GraphLayout; //导入依赖的package包/类
/** Run a test and output the memory footprint of the registry. */
@SuppressWarnings("PMD")
public static void main(String[] args) {
  if (args.length < 2) {
    System.out.println("Usage: perf <registry> <test>");
    System.exit(1);
  }

  Registry registry = run(args[0], args[1]);

  GraphLayout igraph = GraphLayout.parseInstance(registry);
  System.out.println(igraph.toFootprint());
}
 

import org.openjdk.jol.info.GraphLayout; //导入依赖的package包/类
private void checkMemoryUsage(Registry registry, long limit) {
  GraphLayout graph = GraphLayout.parseInstance(registry);
  long size = graph.totalSize();
  String details = "memory use exceeds limit: " + size + " > " + limit + "\n\n" + graph.toFootprint();
  //System.out.println(details);
  Assert.assertTrue(details, size <= limit);
}
 

import org.openjdk.jol.info.GraphLayout; //导入依赖的package包/类
public static void main(String[] args) throws Exception {
    log.info("various vm properties visible via the unsafe");
    log.info(VMSupport.vmDetails());

    log.info("memory layout based on class object at runtime");
    log.info(ClassLayout.parseClass(CodableFieldInfo.class).toPrintable());

    log.info("runtime footprint for the standard java string object for 'heylo friend'");
    String sample = "heylo friend";
    log.info(GraphLayout.parseInstance(sample).toFootprint());
}
 

import org.openjdk.jol.info.GraphLayout; //导入依赖的package包/类
public static void main(String[] args) throws Exception {
    log.info("various vm properties visible via the unsafe");
    log.info(VMSupport.vmDetails());

    log.info("memory layout based on class object at runtime; should see 4 'free bytes' to spend");
    log.info(ClassLayout.parseClass(ByteArrayReadOnlyAsciiBuf.class).toPrintable());

    log.info("runtime footprint for the standard java string object for 'heylo friend'");
    String sample = "heylo friend";
    log.info(GraphLayout.parseInstance(sample).toFootprint());

    log.info("runtime footprint for a ByteArrayReadOnlyUtfBuf object for 'heylo friend'");
    ByteArrayReadOnlyUtfBuf utfBuf = new ByteArrayReadOnlyUtfBuf(sample);
    log.info(GraphLayout.parseInstance(utfBuf).toFootprint());
}
 

import org.openjdk.jol.info.GraphLayout; //导入依赖的package包/类
public static void main(String[] args) throws Exception {
    out.println(VM.current().details());

    Map<String, String> chm = new ConcurrentHashMap<String, String>();

    GraphLayout gl1 = GraphLayout.parseInstance(chm);

    chm.put("Foo", "Bar");
    GraphLayout gl2 = GraphLayout.parseInstance(chm);

    chm.put("Foo2", "Bar2");
    GraphLayout gl3 = GraphLayout.parseInstance(chm);

    System.out.println(gl2.subtract(gl1).toPrintable());
    System.out.println(gl3.subtract(gl2).toPrintable());
}
 

import org.openjdk.jol.info.GraphLayout; //导入依赖的package包/类
public static void main(String[] args) throws Exception {
    out.println(VM.current().details());

    PrintWriter pw = new PrintWriter(System.out, true);

    // create links
    L l1 = new L1();
    L l2 = new L2();
    L l3 = new L3();
    L l4 = new L4();
    L l5 = new L5();
    L l6 = new L6();

    // bind the ring
    l1.bind(l2);
    l2.bind(l3);
    l3.bind(l4);
    l4.bind(l5);
    l5.bind(l6);
    l6.bind(l1);

    // current root
    L r = l1;

    // break all other roots
    l1 = l2 = l3 = l4 = l5 = l6 = null;

    long lastAddr = VM.current().addressOf(r);
    pw.printf("Fresh object is at %x%n", lastAddr);

    int moves = 0;
    for (int i = 0; i < 100000; i++) {

        // scan for L1 and determine it's address
        L s = r;
        while (!((s = s.link()) instanceof L1)) ;

        long cur = VM.current().addressOf(s);
        s = null;

        // if L1 had moved, then probably the entire ring had also moved
        if (cur != lastAddr) {
            moves++;
            pw.printf("*** Move %2d, L1 is at %x%n", moves, cur);
            pw.println("*** Root is " + r.getClass());

            pw.println(GraphLayout.parseInstance(r).toPrintable());

            // select another link
            Random random = new Random();
            for (int c = 0; c < random.nextInt(100); c++) {
                r = r.link();
            }

            lastAddr = cur;
        }

        // make garbage
        for (int c = 0; c < 10000; c++) {
            sink = new Object();
        }
    }

    pw.close();
}
 

import org.openjdk.jol.info.GraphLayout; //导入依赖的package包/类
static void printUsage(Object obj) {
    long total = GraphLayout.parseInstance(obj).totalSize();
    long perItem = Math.round((double) (total) / SIZE);
    System.out.println(String.format("%-30s: %-6d bytes\t(%-3d b/item)", obj.getClass(), total, perItem));
}
 

import org.openjdk.jol.info.GraphLayout; //导入依赖的package包/类
@Test
public void testPercolationSize()
        throws Exception {
    long percolationSize = GraphLayout.parseInstance(p).totalSize();
    assertThat(percolationSize, lessThanOrEqualTo(11 * size * size + 128 * size + 1024));
}