java synchronized atomic_synchronized与atomic性能对比
写了两个例子，对这两种机制进行对比，发现性能差距在6倍以上。
synchronized的例子：
public class SyncInc {
public static void main(String[] args) {
CountDownLatch latch = new CountDownLatch(10);
long begin = System.nanoTime();
for (int i = 0; i < 10; i++) {
new Thread() {
@Override
public void run() {
while (Number.get() < 100_000_000) {
Number.inc();
}
latch.countDown();
}
}.start();
}
try {
latch.await();
System.out.println("took " + (System.nanoTime() - begin) / 1_000_000 + " ms");
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
class Number {
public static volatile int value = 0;
public static synchronized void inc() {
value++;
}
public static int get() {
return value;
}
Atomic的例子：
public class AtomicInc {
public static void main(String[] args) {
CountDownLatch latch = new CountDownLatch(10);
long begin = System.nanoTime();
for (int i = 0; i < 10; i++) {
new Thread() {
@Override
public void run() {
while (AtomicNumber.get() < 100_000_000) {
AtomicNumber.inc();
}
latch.countDown();
}
}.start();
}
try {
latch.await();
System.out.println("took " + (System.nanoTime() - begin) / 1_000_000 + " ms");
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
class AtomicNumber {
public static AtomicInteger value = new AtomicInteger(0);
public static void inc() {
value.incrementAndGet();
}
public static int get() {
return value.get();
}
}
写了两个例子，对这两种机制进行对比，发现性能差距在6倍以上。 synchronized的例子： public class SyncInc { public static void main(String[] args) { CountDownLatch latch = new CountDownLatch(10); long begin = System.nanoTime(); for (int i = 0; i < 10; i++) { new Thread() { @Override public void run() { while (Number.get() < 100_000_000) { Number.inc(); } latch.countDown(); } }.start(); } try { latch.await(); System.out.println("took " + (System.nanoTime() - begin) / 1_000_000 + " ms"); } catch (InterruptedException e) { e.printStackTrace(); } } } class Number { public static volatile int value = 0; public static synchronized void inc() { value++; } public static int get() { return value; } Atomic的例子： public class AtomicInc { public static void main(String[] args) { CountDownLatch latch = new CountDownLatch(10); long begin = System.nanoTime(); for (int i = 0; i < 10; i++) { new Thread() { @Override public void run() { while (AtomicNumber.get() < 100_000_000) { AtomicNumber.inc(); } latch.countDown(); } }.start(); } try { latch.await(); System.out.println("took " + (System.nanoTime() - begin) / 1_000_000 + " ms"); } catch (InterruptedException e) { e.printStackTrace(); } } } class AtomicNumber { public static AtomicInteger value = new AtomicInteger(0); public static void inc() { value.incrementAndGet(); } public static int get() { return value.get(); } }