19. 3 questions

20. 2 solutions

21. 1 problem

23. Multithreading

24. Multithreading

25. Multithreading

26. Multithreading

27. Parallel computing

28. Parallel computing

29. Parallel computing

30. Parallel computing

31. Parallel computing

32. Parallel computing

33. Java & API

34. Java & API

35. http://www.flickr.com/photos/jmchuff/

36. Multicore processors

37. Multicore processors

38. Multicore processors

39. On the sofware side

40. On the sofware side

45. A classical example
public class Singleton {
private static Singleton instance ;
private Singleton() {}
public static Singleton getInstance() {
if (instance == null) {
instance = new Singleton() ;
}
return instance ;
}
}

46. A classical example

47. A classical example

48. A classical example
public class Singleton {
private static Singleton instance ;
private Singleton() {}
public static Singleton getInstance() {
if (instance == null) {
instance = new Singleton() ;
}
return instance ;
}
}

49. A classical example
public class Singleton {
private static Singleton instance ;
private Singleton() {}
public static synchronized Singleton getInstance() {
if (instance == null) {
instance = new Singleton() ;
}
return instance ;
}
}

50. A classical example
public class Singleton {
private static Singleton instance ;
private Singleton() {}
public static synchronized Singleton getInstance() {
if (instance == null) {
instance = new Singleton() ;
}
return instance ;
}
}

51. A classical example
public class Singleton {
private static Singleton instance ;
private Singleton() {}
public static synchronized Singleton getInstance() {
if (instance == null) {
instance = new Singleton() ;
}
return instance ;
}
}

52. A classical example

53. A classical example

54. A classical example
public class Singleton {
private static Singleton instance ;
private Singleton() {}
public static synchronized Singleton getInstance() {
if (instance == null) {
instance = new Singleton() ;
}
return instance ;
}
}

55. A classical example
public class Singleton {
private static Singleton instance ;
public static Singleton getInstance() {
if (instance == null) {
synchronized (Singleton.class) {
if (instance == null) {
instance = new Singleton() ;
}
}
}
return instance ;
}
}

56. A classical example
public class Singleton {
private static Singleton instance ;
public static Singleton getInstance() {
if (instance == null) {
synchronized (Singleton.class) {
if (instance == null) {
instance = new Singleton() ;
}
}
}
return instance ;
}
}

57. A classical example
public class Singleton {
private static Singleton instance ;
public static Singleton getInstance() {
if (instance == null) {
synchronized (Singleton.class) {
if (instance == null) {
instance = new Singleton() ;
}
}
}
return instance ;
}
}

58. Solution to the « data race »

59. Solution to the « data race »

60. Solution to the « data race »

61. Solution to the « data race »

62. Solution to the « data race »

64. The JLS

65. The JLS

66. The JLS

67. The JLS

68. The JLS

69. The JLS

70. The JLS

71. The JLS

72. The JLS

73. The JLS

74. Happens before
x = 1
r1 = x

75. Happens before
x = 1
r1 = x

76. Happens before
x = 1
r1 = x

77. Happens before
x = 1
r1 = x
r1 1

78. Happens before

79. Happens before

80. Example : normal read / write
private int index ;
public void gloriousIncrementation() {
index++ ;
}
public void happyTesting() {
if (index > 10) {
System.out.println("Index is BIG!") ;
}
}

81. Example : normal read / write
private int index ;
public void gloriousIncrementation() {
index++ ;
}
public void happyTesting() {
if (index > 10) {
System.out.println("Index is BIG!") ;
}
}

82. Example : volatile read / write
private volatile int index ;
public void gloriousIncrementation() {
index++ ;
}
public void happyTesting() {
if (index > 10) {
System.out.println("Index is BIG!") ;
}
}

83. Problematic case
private int x, y, r1, r2 ;
private Object lock = new Object() ;
public void niceMethod() { public void coolMethod() {
x = 1 ; synchronized(lock) {
synchronized(lock) { r1 = y ;
y = 1 ; }
} r2 = x ;
} }

84. Problematic case
private int x, y, r1, r2 ;
private Object lock = new Object() ;
public void niceMethod() { public void coolMethod() {
x = 1 ; synchronized(lock) {
synchronized(lock) { r1 = y ;
y = 1 ; }
} r2 = x ;
} }

85. Problematic case
private int x, y, r1, r2 ;
private Object lock = new Object() ;
public void niceMethod() { public void coolMethod() {
x = 1 ; synchronized(lock) {
synchronized(lock) { r1 = y ;
y = 1 ; }
} r2 = x ;
} }

86. Problematic case
private int x, y, r1, r2 ;
private Object lock = new Object() ;
public void niceMethod() { public void coolMethod() {
x = 1 ; synchronized(lock) {
synchronized(lock) { r1 = y ;
y = 1 ; }
} r2 = x ;
} }
r1 = 1, r2 = 1

87. Problematic case
private int x, y, r1, r2 ;
private Object lock = new Object() ;
public void niceMethod() { public void coolMethod() {
x = 1 ; synchronized(lock) {
synchronized(lock) { r1 = y ;
y = 1 ; }
} r2 = x ;
} }

88. Problematic case
private int x, y, r1, r2 ;
private Object lock = new Object() ;
public void niceMethod() { public void coolMethod() {
x = 1 ; synchronized(lock) {
synchronized(lock) { r1 = y ;
y = 1 ; }
} r2 = x ;
} }

89. Problematic case
private int x, y, r1, r2 ;
private Object lock = new Object() ;
public void niceMethod() { public void coolMethod() {
x = 1 ; synchronized(lock) {
synchronized(lock) { r1 = y ;
y = 1 ; }
} r2 = x ;
} }
r1 = 0, r2 = ?

90. Back to the double check locking
public class Singleton {
private static Singleton instance ;
public static Singleton getInstance() {
if (instance == null) {
synchronized (Singleton.class) {
if (instance == null) {
instance = new Singleton() ;
}
}
}
return instance ;
}
}

91. Back to the double check locking
public class Singleton {
private static Singleton instance ;
public static Singleton getInstance() {
if (instance == null) {
synchronized (Singleton.class) {
if (instance == null) {
instance = new Singleton() ;
}
}
}
return instance ;
}
}

92. Back to the double check locking
public class Singleton {
private static Singleton instance ;
public static Singleton getInstance() {
if (instance == null) {
synchronized (Singleton.class) {
if (instance == null) {
instance = new Singleton() ;
}
}
}
return instance ;
}
}

93. Back to the double check locking
public class Singleton {
private static Singleton instance ;
public static Singleton getInstance() {
if (instance == null) {
synchronized (Singleton.class) {
if (instance == null) {
instance = new Singleton() ;
}
}
}
return instance ;
}
}

94. Back to the double check locking
public class Singleton {
private static volatile Singleton instance ;
public static Singleton getInstance() {
if (instance == null) {
synchronized (Singleton.class) {
if (instance == null) {
instance = new Singleton() ;
}
}
}
return instance ;
}
}

95. Is there an elegant solution ?

96. Is there an elegant solution ?
public enum Singleton {
instance ;
}

97. Is there an elegant solution ?
public enum Singleton {
instance ;
}

103. Example
private Object o = new Object() ;
private int index = 0 ;
public void slickMethod() {
synchronized (o) {
index++ ;
}
}

104. Example
private Object o = new Object() ;
private int index = 0 ;
public void slickMethod() {
synchronized (o) {
index++ ;
}
}

105. Example
private Object o = new Object() ;
private int index = 0 ;
public void slickMethod() {
synchronized (o) {
index++ ;
}
}

111. Memory barrier

112. Memory barrier

115. Optimization 1

116. Optimization 1

117. Optimization 1

118. Optimization 1

121. Optimization 2

122. Optimization 2

123. Cache trap !

124. Cache trap !

137. False sharing

138. False sharing

139. Variable padding

140. public class Sequence {
private static final AtomicLongFieldUpdater<Sequence> updater =
AtomicLongFieldUpdater.newUpdater(Sequence.class, "value");
private volatile long p1 = 7L, p2 = 7L, p3 = 7L, p4 = 7L,
p5 = 7L, p6 = 7L, p7 = 7L ;
private volatile long value = Sequencer.INITIAL_CURSOR_VALUE ;
private volatile long q1 = 7L, q2 = 7L, q3 = 7L, q4 = 7L,
q5 = 7L, q6 = 7L, q7 = 7L;
// ...
public long sumPaddingToPreventOptimisation() {
return p1 + p2 + p3 + p4 + p5 + p6 + p7 + value +
q1 + q2 + q3 + q4 + q5 + q6 + q7;
}
public void setPaddingValue(final long value) {
p1 = p2 = p3 = p4 = p5 = p6 = p7 = q1 = q2 = q3 = q4 = q5 = q6 = q7 = value;
}
}

141. package java.util.concurrent;
/**
*
* @since 1.7
* @author Doug Lea
*/
public class ThreadLocalRandom extends Random {
/**
* The random seed. We can't use super.seed.
*/
private long rnd;
// Padding to help avoid memory contention among seed updates in
// different TLRs in the common case that they are located near
// each other.
private long pad0, pad1, pad2, pad3, pad4, pad5, pad6, pad7;
}

142. How to write efficient concurrent code ?

143. How to write efficient concurrent code ?

146. Runnable r = new Runnable() {
public void run() {
while (true) {
System.out.println(« Let’s go sailing !") ;
}
}
} ;
Thread t = new Thread(r) ;
t.start() ;

147. ExecutorService service = new ScheduledThreadPoolExecutor(10) ;
Callable<Boolean> task = new Callable<Boolean>() {
public Boolean call() throws Exception {
int i = 0 ;
while (i++ < 1000) {
System.out.println("Let’s go swimming !") ;
}
return true ;
}
};
Future<Boolean> f = service.submit(task) ;
Boolean b = f.get(100, TimeUnit.MILLISECONDS) ;

149. private Object o = new Object() ;
private int index = 0 ;
public void saltyMethod() {
synchronized (o) {
index++ ;
}
}
private Object o = new Object() ;
private int volatile index = 0 ;
public void pepperedMethod() {
index++ ;
}

150. Lock interface
private Lock lock = new ReentrantLock() ;
public void crispyMethod() {
lock.lock() ; // blocking call as synchronized
// ...
lock.unlock() ;
} ;

151. Lock interface
private Lock lock = new ReentrantLock() ;
public void crispyMethod() {
lock.tryLock(10, TimeUnit.MILLISECONDS) ; // timeout
// ...
lock.unlock() ;
} ;

152. Semaphore interface
private Semaphore s = new Semaphore(5) ;
public void maMethode() {
s.acquire() ; // blocking call as synchronized
// ...
s.release() ;
} ;

153. Semaphore interface
private Semaphore s = new Semaphore(5) ;
public void maMethode() {
s.tryAcquire(10, TimeUnit.MILLISECONDS) ; // timeout
// ...
s.release() ;
} ;

154. Semaphore interface

155. CountDownLatch Class
private CountDownLatch latch = new CountDownLatch() ;
public void init() {
db.connect() ; // slow operation
latch.countDown() ; // openning of the latch
} ;
public void process() {
latch.await() ; // blocks until the latch is openned
} ;

156. CyclicBarrier Class
private CyclicBarrier barrier = new CyclicBarrier(2) ;
public void processOne() {
// ...
barrier.await() ; // blocks until 4 calls
} ;
public void processTwo() {
// ...
barrier.await(10, TimeUnit.MICROSECONDS) ;
} ;

157. ReadWriteLock Interface

158. ReadWriteLock Interface
private ReadWriteLock rwLock = new ReentrantReadWriteLock() ;
public void aMethodThatReads() { public void aMethodThatWrites() {
Lock readLock = rwLock.readLock() ; Lock writeLock = rwLock.writeLock() ;
readLock.lock() ; writeLock.lock() ;
// reading... // writing...
readLock.unlock() ; writeLock.unlock() ;
} ; } ;

160. Atomic types
private AtomicInteger index = new AtomicInteger(0) ;
public void uneMethode() {
long newValue = index.incrementAndGet() ;
}

161. Compare and swap = CAS

162. Compare and swap = CAS
public final long incrementAndGet() {
for (;;) {
long current = get() ;
long next = current + 1 ;
if (compareAndSet(current, next))
return next ;
}
}

164. Queue & BlockingQueue interfaces

165. Queue & BlockingQueue interfaces

166. Queue & BlockingQueue interfaces

167. Queue & BlockingQueue interfaces

168. Queue & BlockingQueue interfaces
add(e) offer(e) put(e) offer(e,
time, unit)
remove() poll() take() poll(e,
time, unit)
element() peek() - -

170. CopyOnWriteArrayList

171. CopyOnWriteArrayList

180. Immutability

181. Immutability

182. Immutability

203. Try trees

204. Immutable systems

207. In databases…
begin
update ... set ... where ...
commit

208. In databases…
begin
update ... set ... where ...
commit

209. In databases…

210. In databases…

211. STM Pattern
<dependency>
<groupId>se.scalablesolutions.akka</groupId>
<artifactId>akka-kernel</artifactId>
<version>1.3.1</version>
</dependency>
<repository>
<id>Akka</id>
<name>Akka Maven2 Repository</name>
<url>http://akka.io/repository/</url>
</repository>

212. STM Pattern
final Ref<Integer> source = new Ref<Integer>(500) ;
final Atomic<Object> atom = new Atomic<Object>() {
@Override
public Object atomically() {
source.swap(source.get() + 1) ;
return null ;
}
} ;
atom.execute() ;

213. STM Pattern
final Ref<Integer> source = new Ref<Integer>(500) ;
final Atomic<Object> atom = new Atomic<Object>() {
@Override
public Object atomically() {
source.swap(source.get() + 1) ;
return null ;
}
} ;
atom.execute() ;

214. STM Pattern
final Ref<Integer> source = new Ref<Integer>(500) ;
final Atomic<Object> atom = new Atomic<Object>() {
@Override
public Object atomically() {
source.swap(source.get() + 1) ;
return null ;
}
} ;
atom.execute() ;

215. STM Pattern

216. STM Pattern

217. STM Pattern
List<E> queue1 = new ... ;
List<E> queue2 = new ... ;
final Ref<List<E>> refQueue1 =
new Ref<List<E>>(Collections.unmodifiableList(queue1)) ;
final Ref<List<E>> refQueue2 =
new Ref<List<E>>(Collections.unmodifiableList(queue2)) ;

218. final Atomic<Object> atom = new Atomic<Object>() {
@Override
public Object atomically() {
// duplication
List<E> dupQ1 = new ArrayList<>(refQueue1) ;
List<E> dupQ2 = new ArrayList<>(refQueue2) ;
// transfer
E element = duqQ1.remove(...) ;
duqQ2.add(element) ;
// swapping
refQueue1.swap(Collections.unmodifiableList(dupQ1) ;
refQueue2.swap(Collections.unmodifiableList(dupQ2) ;
}
} ;

219. STM : implementation

220. STM : implementation

221. STM : why is it so important ?

222. STM : why is it so important ?

223. STM : why is it so important ?

224. STM : why is it so important ?

225. STM : why is it so important ?

226. STM : why is it so important ?

227. STM : why is it so important ?

229. Actors

230. Actors

231. Akka Actors

232. Akka Actors

233. Akka Actors
public class Vador extends UntypedActor {
public void onReceive(Object o) throws Exception {
// o is the message
// return something ;
getContext().reply(something) ;
}
}

234. Akka Actors
public static void main(String[] args) {
Message message = new Message() ;
ActorRef jeff =
Actors.actorOf(Vader.class).start() ;
Future future =
jeff.sendRequestReplyFuture(message) ;
// a bit further away
// beware, it’s not our good ol’ concurrent Future
result = future.get() ;
}

235. Akka Actors

236. public class PrimeFinderActor extends UntypedActor {
public void onReceive(Object o) throws Exception {
List<Integer> bounds = (List<Integer>)o ;
int debut = bounds.get(0) ;
int fin = bounds.get(1) ;
PrimeFactors pfs = new PrimeFactors() ;
for (int i = start ; i < end ; i++) {
PrimeFactors pfi = pfs.getPrimeFactors(i) ;
pfs.add(pfi) ;
}
// return pfs ;
getContext().reply(pfs) ;
}
}

237. public class PrimeFactorCallable implements Callable<PrimeFactors> {
private int debut, fin ;
public PrimeFactorCallable(int debut, int fin) {
this.debut = debut ; this.fin = fin ;
}
public PrimeFactors call() throws Exception {
PrimeFactors pfs = new PrimeFactors() ;
for (int i = debut ; i < fin ; i++) {
PrimeFactors pfi = pfs.getPrimeFactors(i) ;
pfs.add(pfi) ;
}
return pfs ;
}
}

238. public static void main(String[] args) {
Future [] futures = new Future [400] ; // it’s the Akka Future
for (int i = 0 ; i < futures.length ; i++) {
List<Integer> bound = Collections.unmodifiableList(
Arrays.asList(10*i, 10*(i + 1))) ;
ActorRef primeFactorFinder =
Actors.actorOf(PrimeFinderActor.class).start() ;
futures[i] = primeFactorFinder.sendRequestReplyFuture(bound) ;
}
PrimeFactors pfs = new PrimeFactors() ;
for (int i = 0 ; i < futures.length ; i++) {
pfs.add((PrimeFactors)futures[i].get()) ;
}
Actors.registry().shutdownAll() ;
}

239. public static void main(String... args)
throws ExecutionException, InterruptedException {
ExecutorService es = new ScheduledThreadPoolExecutor(10) ;
Future [] futures = new Future [400] ;
for (int i = 0 ; i < futures.length ; i++) {
PrimeFactorCallable callable =
new PrimeFactorCallable(10*i, 10*(i + 1)) ;
futures[i] = es.submit(callable) ;
}
PrimeFactors pfs = new PrimeFactors() ;
for (int i = 0 ; i < futures.length ; i++) {
pfs.add((PrimeFactors)futures[i].get()) ;
}
es.shutdown() ;
}

240. BTW, the result is…
[2^3989][3^1996][5^996][7^664][11^399][13^331][17^248][19^221][23^180][29^141][31^133][37^110][41^99][43^95][47^86][53^76][59^68][61^66][67^59]
[71^56][73^54][79^50][83^48][89^44][97^41][101^39][103^38][107^37][109^36][113^35][127^31][131^30][137^29][139^28][149^26][151^26][157^25][163^
24][167^23][173^23][179^22][181^22][191^20][193^20][197^20][199^20][211^18][223^17][227^17][229^17][233^17][239^16][241^16][251^15][257^15][263
^15][269^14][271^14][277^14][281^14][283^14][293^13][307^13][311^12][313^12][317^12][331^12][337^11][347^11][349^11][353^11][359^11][367^10][37
3^10][379^10][383^10][389^10][397^10][401^9][409^9][419^9][421^9][431^9][433^9][439^9][443^9][449^8][457^8][461^8][463^8][467^8][479^8][487^8][
491^8][499^8][503^7][509^7][521^7][523^7][541^7][547^7][557^7][563^7][569^7][571^7][577^6][587^6][593^6][599^6][601^6][607^6][613^6][617^6][619
^6][631^6][641^6][643^6][647^6][653^6][659^6][661^6][673^5][677^5][683^5][691^5][701^5][709^5][719^5][727^5][733^5][739^5][743^5][751^5][757^5]
[761^5][769^5][773^5][787^5][797^5][809^4][811^4][821^4][823^4][827^4][829^4][839^4][853^4][857^4][859^4][863^4][877^4][881^4][883^4][887^4][90
7^4][911^4][919^4][929^4][937^4][941^4][947^4][953^4][967^4][971^4][977^4][983^4][991^4][997^4][1009^3][1013^3][1019^3][1021^3][1031^3][1033^3]
[1039^3][1049^3][1051^3][1061^3][1063^3][1069^3][1087^3][1091^3][1093^3][1097^3][1103^3][1109^3][1117^3][1123^3][1129^3][1151^3][1153^3][1163^3
][1171^3][1181^3][1187^3][1193^3][1201^3][1213^3][1217^3][1223^3][1229^3][1231^3][1237^3][1249^3][1259^3][1277^3][1279^3][1283^3][1289^3][1291^
3][1297^3][1301^3][1303^3][1307^3][1319^3][1321^3][1327^3][1361^2][1367^2][1373^2][1381^2][1399^2][1409^2][1423^2][1427^2][1429^2][1433^2][1439
^2][1447^2][1451^2][1453^2][1459^2][1471^2][1481^2][1483^2][1487^2][1489^2][1493^2][1499^2][1511^2][1523^2][1531^2][1543^2][1549^2][1553^2][155
9^2][1567^2][1571^2][1579^2][1583^2][1597^2][1601^2][1607^2][1609^2][1613^2][1619^2][1621^2][1627^2][1637^2][1657^2][1663^2][1667^2][1669^2][16
93^2][1697^2][1699^2][1709^2][1721^2][1723^2][1733^2][1741^2][1747^2][1753^2][1759^2][1777^2][1783^2][1787^2][1789^2][1801^2][1811^2][1823^2][1
831^2][1847^2][1861^2][1867^2][1871^2][1873^2][1877^2][1879^2][1889^2][1901^2][1907^2][1913^2][1931^2][1933^2][1949^2][1951^2][1973^2][1979^2][
1987^2][1993^2][1997^2][1999^2][2003^1][2011^1][2017^1][2027^1][2029^1][2039^1][2053^1][2063^1][2069^1][2081^1][2083^1][2087^1][2089^1][2099^1]
[2111^1][2113^1][2129^1][2131^1][2137^1][2141^1][2143^1][2153^1][2161^1][2179^1][2203^1][2207^1][2213^1][2221^1][2237^1][2239^1][2243^1][2251^1
][2267^1][2269^1][2273^1][2281^1][2287^1][2293^1][2297^1][2309^1][2311^1][2333^1][2339^1][2341^1][2347^1][2351^1][2357^1][2371^1][2377^1][2381^
1][2383^1][2389^1][2393^1][2399^1][2411^1][2417^1][2423^1][2437^1][2441^1][2447^1][2459^1][2467^1][2473^1][2477^1][2503^1][2521^1][2531^1][2539
^1][2543^1][2549^1][2551^1][2557^1][2579^1][2591^1][2593^1][2609^1][2617^1][2621^1][2633^1][2647^1][2657^1][2659^1][2663^1][2671^1][2677^1][268
3^1][2687^1][2689^1][2693^1][2699^1][2707^1][2711^1][2713^1][2719^1][2729^1][2731^1][2741^1][2749^1][2753^1][2767^1][2777^1][2789^1][2791^1][27
97^1][2801^1][2803^1][2819^1][2833^1][2837^1][2843^1][2851^1][2857^1][2861^1][2879^1][2887^1][2897^1][2903^1][2909^1][2917^1][2927^1][2939^1][2
953^1][2957^1][2963^1][2969^1][2971^1][2999^1][3001^1][3011^1][3019^1][3023^1][3037^1][3041^1][3049^1][3061^1][3067^1][3079^1][3083^1][3089^1][
3109^1][3119^1][3121^1][3137^1][3163^1][3167^1][3169^1][3181^1][3187^1][3191^1][3203^1][3209^1][3217^1][3221^1][3229^1][3251^1][3253^1][3257^1]
[3259^1][3271^1][3299^1][3301^1][3307^1][3313^1][3319^1][3323^1][3329^1][3331^1][3343^1][3347^1][3359^1][3361^1][3371^1][3373^1][3389^1][3391^1
][3407^1][3413^1][3433^1][3449^1][3457^1][3461^1][3463^1][3467^1][3469^1][3491^1][3499^1][3511^1][3517^1][3527^1][3529^1][3533^1][3539^1][3541^
1][3547^1][3557^1][3559^1][3571^1][3581^1][3583^1][3593^1][3607^1][3613^1][3617^1][3623^1][3631^1][3637^1][3643^1][3659^1][3671^1][3673^1][3677
^1][3691^1][3697^1][3701^1][3709^1][3719^1][3727^1][3733^1][3739^1][3761^1][3767^1][3769^1][3779^1][3793^1][3797^1][3803^1][3821^1][3823^1][383
3^1][3847^1][3851^1][3853^1][3863^1][3877^1][3881^1][3889^1][3907^1][3911^1][3917^1][3919^1][3923^1][3929^1][3931^1][3943^1][3947^1][3967^1][39
89^1]

241. Akka Actors

242. Akka Actors + STM

243. Akka Actors + STM

244. public class Balance { public class Deposit {
public final int amount ; public final int amount ;
public Balance(int amount) { public Deposit(int amount) {
this.amount = amount ; this.amount = amount ;
} }
} }
public class Withdrawal { public class GetBalance {
public final int amount ; }
public Balance(int amount) {
this.amount = amount ;
}
}

245. public class BankAccount extends UntypedTransactor {
private final Ref<Integer> balance = new Ref<Integer>(0) ;
public void atomically(final Object message) {
if (message instanceof Deposit) {
int amount = ((Deposit)message).amount ;
if (amount > 0)
balance.swap(balance.get() + amount) ;
}
if (message instanceof Withdrawal) {
int amount = ((Retrait)message).amount ;
if (amount > 0) {
if (balance.get() < amount) throw new IllegalStateException("...") ;
balance.swap(balance.get() - amount) ;
}
}
if (message instanceof GetBalance)
getContext().replySafe((new Balance(balance.get()))) ;
}
}

246. public class BankAccount extends UntypedTransactor {
private final Ref<Integer> balance = new Ref<Integer>(0) ;
public void atomically(final Object message) {
if (message instanceof Deposit) {
int amount = ((Deposit)message).amount ;
if (amount > 0)
balance.swap(balance.get() + amount) ;
}
if (message instanceof Withdrawal) {
int amount = ((Retrait)message).amount ;
if (amount > 0) {
if (balance.get() < amount) throw new IllegalStateException("...") ;
balance.swap(balance.get() - amount) ;
}
}
if (message instanceof GetBalance)
getContext().replySafe((new Balance(balance.get()))) ;
}
}

247. public class BankAccount extends UntypedTransactor {
private final Ref<Integer> balance = new Ref<Integer>(0) ;
public void atomically(final Object message) {
if (message instanceof Deposit) {
int amount = ((Deposit)message).amount ;
if (amount > 0)
balance.swap(balance.get() + amount) ;
}
if (message instanceof Withdrawal) {
int amount = ((Retrait)message).amount ;
if (amount > 0) {
if (balance.get() < amount) throw new IllegalStateException("...") ;
balance.swap(balance.get() - amount) ;
}
}
if (message instanceof GetBalance)
getContext().replySafe((new Balance(balance.get()))) ;
}
}

248. public class BankAccount extends UntypedTransactor {
private final Ref<Integer> balance = new Ref<Integer>(0) ;
public void atomically(final Object message) {
if (message instanceof Deposit) {
int amount = ((Deposit)message).amount ;
if (amount > 0)
balance.swap(balance.get() + amount) ;
}
if (message instanceof Withdrawal) {
int amount = ((Retrait)message).amount ;
if (amount > 0) {
if (balance.get() < amount) throw new IllegalStateException("...") ;
balance.swap(balance.get() - amount) ;
}
}
if (message instanceof GetBalance)
getContext().replySafe((new Balance(balance.get()))) ;
}
}

249. public class Transfer {
public final ActorRef source ;
public final ActorRef destination ;
public final int amount ;
public Transfert(
final ActorRef source,
final ActorRef destination,
final int amount) {
this.source = source ;
this.destination = destination ;
this.amount = amount ;
}
}

250. public class BankService extends UntypedTransactor {
public Set<SendTo> coordinate(final Object message) {
if (message instanceof Transfer) {
Set<SendTo> s = new HashSet<SendTo>() ;
Transfer t = (Transfer)message ;
if (t.amount > 0) { // validation
s.add(sendTo(t.destination, new Deposit(t.amount))) ;
s.add(sendTo(t.source, new Withdrawal(t.amount))) ;
return Collections.unmodifiableSet(s) ;
}
}
return nobody() ;
}
}

251. public class BankService extends UntypedTransactor {
public Set<SendTo> coordinate(final Object message) {
if (message instanceof Transfer) {
Set<SendTo> s = new HashSet<SendTo>() ;
Transfer t = (Transfer)message ;
if (t.amount > 0) { // validation
s.add(sendTo(t.destination, new Deposit(t.amount))) ;
s.add(sendTo(t.source, new Withdrawal(t.amount))) ;
return Collections.unmodifiableSet(s) ;
}
}
return nobody() ;
}
}

252. public class BankService extends UntypedTransactor {
public Set<SendTo> coordinate(final Object message) {
if (message instanceof Transfer) {
Set<SendTo> s = new HashSet<SendTo>() ;
Transfer t = (Transfer)message ;
if (t.amount > 0) { // validation
s.add(sendTo(t.destination, new Deposit(t.amount))) ;
s.add(sendTo(t.source, new Withdrawal(t.amount))) ;
return Collections.unmodifiableSet(s) ;
}
}
return nobody() ;
}
}

253. public class BankService extends UntypedTransactor {
public Set<SendTo> coordinate(final Object message) {
if (message instanceof Transfer) {
Set<SendTo> s = new HashSet<SendTo>() ;
Transfer t = (Transfer)message ;
if (t.amount > 0) { // validation
s.add(sendTo(t.destination, new Deposit(t.amount))) ;
s.add(sendTo(t.source, new Withdrawal(t.amount))) ;
return Collections.unmodifiableSet(s) ;
}
}
return nobody() ;
}
}

254. public class BankService extends UntypedTransactor {
public Set<SendTo> coordinate(final Object message) {
if (message instanceof Transfer) {
Set<SendTo> s = new HashSet<SendTo>() ;
Transfer t = (Transfer)message ;
if (t.amount > 0) { // validation
s.add(sendTo(t.destination, new Deposit(t.amount))) ;
s.add(sendTo(t.source, new Withdrawal(t.amount))) ;
return Collections.unmodifiableSet(s) ;
}
}
return nobody() ;
}
}

255. Akka actors + STM

256. Akka actors + STM

258. Parallel computing in Java

259. Parallel computing in Java

260. Parallel computing in Java

262. Fork / Join

263. Fork / Join

279. Fork / Join : patterns
ForkJoinPool pool = new ForkJoinPool() ;
PrimeFactorsFinderRecursiveTask task =
new PrimeFactorsFinderRecursiveTask(1, 4000) ;
ForkJoinTask<PrimeFactors> pfsTask = pool.submit(task) ;
PrimeFactors pfs = pfsTask.get() ;

280. public class PrimeFactorsFinderRecursiveTask extends RecursiveTask<PrimeFactors> {
private int start, end ;
protected PrimeFactors compute() {
PrimeFactors pfs = new PrimeFactors() ;
if (end - start > ITERATIONS) { // I’m too big
// processing
ForkJoinTask<PrimeFactors> task = ... ;
task.fork() ;
PrimeFactors pfs = task.get() ;
...
} else {
for (int i = start ; i < end ; i++) {
PrimeFactors pfi = pfs.getPrimeFactors(i) ;
pfs.add(pfi) ;
}
}
return pfs ;
}
}

281. public class PrimeFactorsFinderRecursiveTask extends RecursiveTask<PrimeFactors> {
private int start, end ;
protected PrimeFactors compute() {
PrimeFactors pfs = new PrimeFactors() ;
if (end - start > ITERATIONS) { // I’m too big
// processing
ForkJoinTask<PrimeFactors> task = ... ;
task.fork() ;
PrimeFactors pfs = task.get() ;
...
} else {
for (int i = start ; i < end ; i++) {
PrimeFactors pfi = pfs.getPrimeFactors(i) ;
pfs.add(pfi) ;
}
}
return pfs ;
}
}

282. public class PrimeFactorsFinderRecursiveTask extends RecursiveTask<PrimeFactors> {
private int start, end ;
protected PrimeFactors compute() {
PrimeFactors pfs = new PrimeFactors() ;
if (end - start > ITERATIONS) { // I’m too big
// processing
ForkJoinTask<PrimeFactors> task = ... ;
task.fork() ;
PrimeFactors pfs = task.get() ;
...
} else {
for (int i = start ; i < end ; i++) {
PrimeFactors pfi = pfs.getPrimeFactors(i) ;
pfs.add(pfi) ;
}
}
return pfs ;
}
}

283. Fork / Join : patterns

290. Fork / Join : patterns

294. // 1st strategy
if (end - start > MAX_ITERATIONS) { // I’m too big
int m = (start + end) / 2 ;
PrimeFactorsFinderTask task1 = new PrimeFactorsFinderTask(start, m) ;
PrimeFactorsFinderTask task2 = new PrimeFactorsFinderTask(m, end) ;
task1.fork() ;
task2.fork() ;
PrimeFactors pfs1 = task1.join() ;
PrimeFactors pfs2 = task2.join() ;
pfs.add(pfs1) ;
pfs.add(pfs2) ;
}

295. // 2nd strategy
if (end - start > MAX_ITERATIONS) { // I’m too big
List<ForkJoinTask<PrimeFactors>> pfsList =
new ArrayList<ForkJoinTask<PrimeFactors>>() ;
for (int i = start ; i < end – MAX_ITERATIONS ; i += MAX_ITERATIONS) {
PrimeFactorsFinderRecursiveTask task =
new PrimeFactorsFinderRecursiveTask(i, i + MAX_ITERATIONS) ;
task.fork() ;
pfsList.add(task) ;
}
for (ForkJoinTask<PrimeFactors> task : pfsList) {
PrimeFactors pfsElement = task.join() ;
pfs.add(pfsElement) ;
}
}

297. Parallel Arrays

305. Parallel Arrays : patterns
ForkJoinPool pool = new ForkJoinPool() ; // package !
ParralelLongArray a = ParralelLongArray.create(size, pool) ;

306. Parallel Arrays : patterns
a.replaceWithGeneratedValue(new LongGenerator() {
@Override
public long op() {
return rand.nextInt(100) ;
}
}) ;

307. Parallel Arrays : patterns
Ops.LongPredicate filter = new Ops.LongPredicate() {
@Override
public boolean op(long l1) {
return l1 > 50 ;
}
}
a2 = a.withFilter(filter) ;
a2.all() ;

308. Parallel Arrays : patterns
Ops.LongReducer reducer = new Ops.LongReducer() {
@Override
public long op(long l1, long l2) {
return l1 + l2 ;
}
}
long reducedValue = a.reduce(reducer, 0L) ;

309. Parallel Arrays : patterns
Ops.LongOp add2 = new Ops.LongOp() {
@Override
public long op(long l1) {
return l1 + 2 ;
}
} ;
a2 = a.withMapping(add2) ;

310. Parallel Arrays : patterns
Ops.BinaryLongOp multAB = new Ops.BinaryLongOp() {
@Override
public long op(long l1, long l2) {
return l1*l2 ;
}
} ;
a2 = a0.withMapping(multAB, a1) ;

311. Parallel Arrays : patterns
Ops.LongReducer sum = new Ops.LongReducer() {
@Override
public long op(long l1, long l2) {
return l1 + l2 ;
}
} ;
long normSquare = a0.withMapping(multAB, a0).reduce(sum, 0L) ;
double norm = Math.sqrt(normSquare) ;

312. Parallel Arrays : patterns

314. Java 8
Sept. 2013

315. What are the l ?
Collection<Person> persons = ... ;
int maxAge = persons.map(p -> p.getAge()).reduce(0, Integer::max) ;

316. What are the l ?
Collection<Person> persons = ... ;
int maxAge = persons.map(p -> p.getAge()).reduce(0, Integer::max) ;
Collection<Person> oldies =
persons.filter(p -> p.age > 40).into(new ArrayList()) ;

317. What are the l ?
Collection<Person> persons = ... ;
int maxAge = persons.map(p -> p.getAge()).reduce(0, Integer::max) ;
Collection<Person> oldies =
persons.filter(p -> p.age > 40).into(new ArrayList()) ;

318. What are the l ?
Collection<Person> persons = ... ;
int maxAge = persons.map(p -> p.getAge()).reduce(0, Integer::max) ;
Collection<Person> oldies =
persons.filter(p -> p.age > 40).into(new ArrayList()) ;

319. The new Collection interface
public interface Collection<E> {
public boolean add(E e) ;
public boolean addAll(Collection<? extends E> c) ;
// the usual methods of the Collection interface
// the new stuff
public void sort(Comparator<? super E> comparator)
default Collections.sort(comparator) ;
}

320. Supports parallel() !
Collection<Person> persons = ... ;
int maxAge = persons.parallel().map(p -> p.getAge()).reduce(0, Integer::max) ;
Collection<Person> oldies =
persons.parallel().filter(p -> p.age > 40).into(new ArrayList()) ;

321. Spliterable Interface
public interface Spliterable<E> extends Iterable<E> {
public Iterable<E>[] splits() ;
public Iterable<E>[] splits(
int maxSplits, int minPerSplits, int maxPerSplits) ;
public int naturalSplits() ;
}

322. Going parallel with the JDK 8

324. An anecdot

325. An anecdot

326. An anecdot

327. An anecdot

328. An anecdot

329. An anecdot

330. An anecdot

331. Algorithms

332. Algorithms

333. Algorithms

335. Conclusions

336. Conclusions

337. Conclusions

338. Conclusions

339. Conclusions

340. Conclusions

341. Thank you !

342. Q&A