1. Java
Thread
2011 4 9
twitter: @zaki50

2. Who am I
• YAMAZAKI Makoto(twitter: @zaki50)
• Android
•
• StickyShortcut
• Java

3. • Effective Java 2
• ISBN:978-4-89471-499-1
• 3,780 ( )
• 66, 69

4. Agenda
• synchronized / volatile
• Lock(ReentrantLock)
• java.util.concurrent

5. synchronized

6. Eclipse (jvisualvm)

7. synchronized
class Sample {
public synchronized void execute1() {
//
}
public void execute1b() {
synchronized (this) {
//
}
}
public static synchronized void execute2() {
//
}
public static synchronized void execute2b() {
synchronized (Sample.class) {
//
}
}
}

8. synchronized
•
•
•

9. •

11. •
(by Wikipedia)
• Java 1
1
1
1

12. •
• synchronized
• Object#wait()
•
• synchronized
• Object#wait()

13. •
synchronized
•

14. synchronized
class Sample {
public synchronized void execute1() {
//
}
public void execute1b() {
synchronized (this) {
//
}
}
public static synchronized void execute2() {
//
}
public static synchronized void execute2b() {
synchronized (Sample.class) {
//
}
}
}

15. •

16. •

17. • Java VM
•
•
•

18. private static boolean stopRequested = false;
private static int value = 0;
public static void main(String[] args) throws Exception {
new Thread() {
@Override
public void run() {
int i = 0;
if (!stopRequested) {
while (!stopRequested) { while (true) {
i++; i++;
}
}
}
System.out.println(value);
}
}.start();
TimeUnit.SECONDS.sleep(1L);
value = 100;
stopRequested = true;
}

19. private static boolean stopRequested = false;
private static int value = 0;
public static void main(String[] args) throws Exception {
new Thread() {
@Override
public void run() {
int i = 0;
while (!stopped()) {
i++;
}
System.out.println(value);
}
}.start(); private synchronized static void stop() {
stopRequested = true;
TimeUnit.SECONDS.sleep(1L); }
value = 100;
stop(); private synchronized static boolean stopped() {
} return stopRequested;
}

20. volatile

21. volatile
•
• volatile
• volatile

22. volatile
private volatile static boolean stopRequested = false;
private volatile static int value = 0;
public static void main(String[] args) throws Exception {
new Thread() {
@Override
public void run() {
int i = 0;
while (!stopRequested) {
i++;
}
System.out.println(value);
}
}.start();
TimeUnit.SECONDS.sleep(1L);
value = 100;
stopRequested = true;
}

23. Lock

24. Lock
• synchronized
• lock() // synchronized
• tryLock() //
• tryLock(long,TimeUnit) //
• lockInterruptibly() //

25. •
• try - finally
Lock l = ...;
l.lock();
try {
//
} finally {
l.unlock();
}

26. ReentrantReadWriteLock rwLock = new ReentrantReadWriteLock();
Lock wl = rwLock.writeLock();
Lock rl;
wl.lock();
try {
// write
rl = rwLock.readLock();
} finally {
wl.unlock();
}
try {
// read
} finally {
rl.unlock();
}

27. Lock
• lock() synchronized
• unlock() synchronized
• Lock

28. java.util.concurrent

29. ...
• wait() notify()/notifyAll()
( )
•

30. java.util.concurrent
•
Javadoc of java.util.concurrent
• ExecutorService
•
•
•
• ConcurrentCollections
•

31. • synchronized
• Java 17.4 Memory Model
• java.util.concurrent
• Java
• Doug Lea ISBN:4-7973-3720-6