Java Serialization: The standard method in Java of having an object implement Serializable . Binary via ByteBuffer: A simple protocol using the ByteBuffer API to write the fields of an object in binary format. This is our baseline for what is considered a good binary encoding approach. Binary via Unsafe: Introduction to Unsafe and its collection of methods that allow direct memory manipulation. Here I will show how to get similar performance to C/C++.

The Code

import sun.misc.Unsafe; import java.io.ByteArrayInputStream; import java.io.ByteArrayOutputStream; import java.io.ObjectInputStream; import java.io.ObjectOutputStream; import java.io.Serializable; import java.lang.reflect.Field; import java.nio.ByteBuffer; import java.util.Arrays; public final class TestSerialisationPerf { public static final int REPETITIONS = 1 * 1000 * 1000; private static ObjectToBeSerialised ITEM = new ObjectToBeSerialised( 1010L, true, 777, 99, new double[]{0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0}, new long[]{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}); public static void main(final String[] arg) throws Exception { for (final PerformanceTestCase testCase : testCases) { for (int i = 0; i < 5; i++) { testCase.performTest(); System.out.format("%d %s\twrite=%,dns read=%,dns total=%,dns

", i, testCase.getName(), testCase.getWriteTimeNanos(), testCase.getReadTimeNanos(), testCase.getWriteTimeNanos() + testCase.getReadTimeNanos()); if (!ITEM.equals(testCase.getTestOutput())) { throw new IllegalStateException("Objects do not match"); } System.gc(); Thread.sleep(3000); } } } private static final PerformanceTestCase[] testCases = { new PerformanceTestCase("Serialisation", REPETITIONS, ITEM) { ByteArrayOutputStream baos = new ByteArrayOutputStream(); public void testWrite(ObjectToBeSerialised item) throws Exception { for (int i = 0; i < REPETITIONS; i++) { baos.reset(); ObjectOutputStream oos = new ObjectOutputStream(baos); oos.writeObject(item); oos.close(); } } public ObjectToBeSerialised testRead() throws Exception { ObjectToBeSerialised object = null; for (int i = 0; i < REPETITIONS; i++) { ByteArrayInputStream bais = new ByteArrayInputStream(baos.toByteArray()); ObjectInputStream ois = new ObjectInputStream(bais); object = (ObjectToBeSerialised)ois.readObject(); } return object; } }, new PerformanceTestCase("ByteBuffer", REPETITIONS, ITEM) { ByteBuffer byteBuffer = ByteBuffer.allocate(1024); public void testWrite(ObjectToBeSerialised item) throws Exception { for (int i = 0; i < REPETITIONS; i++) { byteBuffer.clear(); item.write(byteBuffer); } } public ObjectToBeSerialised testRead() throws Exception { ObjectToBeSerialised object = null; for (int i = 0; i < REPETITIONS; i++) { byteBuffer.flip(); object = ObjectToBeSerialised.read(byteBuffer); } return object; } }, new PerformanceTestCase("UnsafeMemory", REPETITIONS, ITEM) { UnsafeMemory buffer = new UnsafeMemory(new byte[1024]); public void testWrite(ObjectToBeSerialised item) throws Exception { for (int i = 0; i < REPETITIONS; i++) { buffer.reset(); item.write(buffer); } } public ObjectToBeSerialised testRead() throws Exception { ObjectToBeSerialised object = null; for (int i = 0; i < REPETITIONS; i++) { buffer.reset(); object = ObjectToBeSerialised.read(buffer); } return object; } }, }; } abstract class PerformanceTestCase { private final String name; private final int repetitions; private final ObjectToBeSerialised testInput; private ObjectToBeSerialised testOutput; private long writeTimeNanos; private long readTimeNanos; public PerformanceTestCase(final String name, final int repetitions, final ObjectToBeSerialised testInput) { this.name = name; this.repetitions = repetitions; this.testInput = testInput; } public String getName() { return name; } public ObjectToBeSerialised getTestOutput() { return testOutput; } public long getWriteTimeNanos() { return writeTimeNanos; } public long getReadTimeNanos() { return readTimeNanos; } public void performTest() throws Exception { final long startWriteNanos = System.nanoTime(); testWrite(testInput); writeTimeNanos = (System.nanoTime() - startWriteNanos) / repetitions; final long startReadNanos = System.nanoTime(); testOutput = testRead(); readTimeNanos = (System.nanoTime() - startReadNanos) / repetitions; } public abstract void testWrite(ObjectToBeSerialised item) throws Exception; public abstract ObjectToBeSerialised testRead() throws Exception; } class ObjectToBeSerialised implements Serializable { private static final long serialVersionUID = 10275539472837495L; private final long sourceId; private final boolean special; private final int orderCode; private final int priority; private final double[] prices; private final long[] quantities; public ObjectToBeSerialised(final long sourceId, final boolean special, final int orderCode, final int priority, final double[] prices, final long[] quantities) { this.sourceId = sourceId; this.special = special; this.orderCode = orderCode; this.priority = priority; this.prices = prices; this.quantities = quantities; } public void write(final ByteBuffer byteBuffer) { byteBuffer.putLong(sourceId); byteBuffer.put((byte)(special ? 1 : 0)); byteBuffer.putInt(orderCode); byteBuffer.putInt(priority); byteBuffer.putInt(prices.length); for (final double price : prices) { byteBuffer.putDouble(price); } byteBuffer.putInt(quantities.length); for (final long quantity : quantities) { byteBuffer.putLong(quantity); } } public static ObjectToBeSerialised read(final ByteBuffer byteBuffer) { final long sourceId = byteBuffer.getLong(); final boolean special = 0 != byteBuffer.get(); final int orderCode = byteBuffer.getInt(); final int priority = byteBuffer.getInt(); final int pricesSize = byteBuffer.getInt(); final double[] prices = new double[pricesSize]; for (int i = 0; i < pricesSize; i++) { prices[i] = byteBuffer.getDouble(); } final int quantitiesSize = byteBuffer.getInt(); final long[] quantities = new long[quantitiesSize]; for (int i = 0; i < quantitiesSize; i++) { quantities[i] = byteBuffer.getLong(); } return new ObjectToBeSerialised(sourceId, special, orderCode, priority, prices, quantities); } public void write(final UnsafeMemory buffer) { buffer.putLong(sourceId); buffer.putBoolean(special); buffer.putInt(orderCode); buffer.putInt(priority); buffer.putDoubleArray(prices); buffer.putLongArray(quantities); } public static ObjectToBeSerialised read(final UnsafeMemory buffer) { final long sourceId = buffer.getLong(); final boolean special = buffer.getBoolean(); final int orderCode = buffer.getInt(); final int priority = buffer.getInt(); final double[] prices = buffer.getDoubleArray(); final long[] quantities = buffer.getLongArray(); return new ObjectToBeSerialised(sourceId, special, orderCode, priority, prices, quantities); } @Override public boolean equals(final Object o) { if (this == o) { return true; } if (o == null || getClass() != o.getClass()) { return false; } final ObjectToBeSerialised that = (ObjectToBeSerialised)o; if (orderCode != that.orderCode) { return false; } if (priority != that.priority) { return false; } if (sourceId != that.sourceId) { return false; } if (special != that.special) { return false; } if (!Arrays.equals(prices, that.prices)) { return false; } if (!Arrays.equals(quantities, that.quantities)) { return false; } return true; } } class UnsafeMemory { private static final Unsafe unsafe; static { try { Field field = Unsafe.class.getDeclaredField("theUnsafe"); field.setAccessible(true); unsafe = (Unsafe)field.get(null); } catch (Exception e) { throw new RuntimeException(e); } } private static final long byteArrayOffset = unsafe.arrayBaseOffset(byte[].class); private static final long longArrayOffset = unsafe.arrayBaseOffset(long[].class); private static final long doubleArrayOffset = unsafe.arrayBaseOffset(double[].class); private static final int SIZE_OF_BOOLEAN = 1; private static final int SIZE_OF_INT = 4; private static final int SIZE_OF_LONG = 8; private int pos = 0; private final byte[] buffer; public UnsafeMemory(final byte[] buffer) { if (null == buffer) { throw new NullPointerException("buffer cannot be null"); } this.buffer = buffer; } public void reset() { this.pos = 0; } public void putBoolean(final boolean value) { unsafe.putBoolean(buffer, byteArrayOffset + pos, value); pos += SIZE_OF_BOOLEAN; } public boolean getBoolean() { boolean value = unsafe.getBoolean(buffer, byteArrayOffset + pos); pos += SIZE_OF_BOOLEAN; return value; } public void putInt(final int value) { unsafe.putInt(buffer, byteArrayOffset + pos, value); pos += SIZE_OF_INT; } public int getInt() { int value = unsafe.getInt(buffer, byteArrayOffset + pos); pos += SIZE_OF_INT; return value; } public void putLong(final long value) { unsafe.putLong(buffer, byteArrayOffset + pos, value); pos += SIZE_OF_LONG; } public long getLong() { long value = unsafe.getLong(buffer, byteArrayOffset + pos); pos += SIZE_OF_LONG; return value; } public void putLongArray(final long[] values) { putInt(values.length); long bytesToCopy = values.length << 3; unsafe.copyMemory(values, longArrayOffset, buffer, byteArrayOffset + pos, bytesToCopy); pos += bytesToCopy; } public long[] getLongArray() { int arraySize = getInt(); long[] values = new long[arraySize]; long bytesToCopy = values.length << 3; unsafe.copyMemory(buffer, byteArrayOffset + pos, values, longArrayOffset, bytesToCopy); pos += bytesToCopy; return values; } public void putDoubleArray(final double[] values) { putInt(values.length); long bytesToCopy = values.length << 3; unsafe.copyMemory(values, doubleArrayOffset, buffer, byteArrayOffset + pos, bytesToCopy); pos += bytesToCopy; } public double[] getDoubleArray() { int arraySize = getInt(); double[] values = new double[arraySize]; long bytesToCopy = values.length << 3; unsafe.copyMemory(buffer, byteArrayOffset + pos, values, doubleArrayOffset, bytesToCopy); pos += bytesToCopy; return values; } }

Results

2.8GHz Nehalem - Java 1.7.0_04 ============================== 0 Serialisation write=2,517ns read=11,570ns total=14,087ns 1 Serialisation write=2,198ns read=11,122ns total=13,320ns 2 Serialisation write=2,190ns read=11,011ns total=13,201ns 3 Serialisation write=2,221ns read=10,972ns total=13,193ns 4 Serialisation write=2,187ns read=10,817ns total=13,004ns 0 ByteBuffer write=264ns read=273ns total=537ns 1 ByteBuffer write=248ns read=243ns total=491ns 2 ByteBuffer write=262ns read=243ns total=505ns 3 ByteBuffer write=300ns read=240ns total=540ns 4 ByteBuffer write=247ns read=243ns total=490ns 0 UnsafeMemory write=99ns read=84ns total=183ns 1 UnsafeMemory write=53ns read=82ns total=135ns 2 UnsafeMemory write=63ns read=66ns total=129ns 3 UnsafeMemory write=46ns read=63ns total=109ns 4 UnsafeMemory write=48ns read=58ns total=106ns 2.4GHz Sandy Bridge - Java 1.7.0_04 =================================== 0 Serialisation write=1,940ns read=9,006ns total=10,946ns 1 Serialisation write=1,674ns read=8,567ns total=10,241ns 2 Serialisation write=1,666ns read=8,680ns total=10,346ns 3 Serialisation write=1,666ns read=8,623ns total=10,289ns 4 Serialisation write=1,715ns read=8,586ns total=10,301ns 0 ByteBuffer write=199ns read=198ns total=397ns 1 ByteBuffer write=176ns read=178ns total=354ns 2 ByteBuffer write=174ns read=174ns total=348ns 3 ByteBuffer write=172ns read=183ns total=355ns 4 ByteBuffer write=174ns read=180ns total=354ns 0 UnsafeMemory write=38ns read=75ns total=113ns 1 UnsafeMemory write=26ns read=52ns total=78ns 2 UnsafeMemory write=26ns read=51ns total=77ns 3 UnsafeMemory write=25ns read=51ns total=76ns 4 UnsafeMemory write=27ns read=50ns total=77ns

Analysis

close()

Unsafe

Adding Some Context

Unsafe

Unsafe

Conclusion

UnsafeMemory

Marshallable

Unsafe