From Runnable and synchronized To atomically() and parallel()

19. 3 questions

20. 2 solutions

21. 1 problem

23. Multithreading

24. Multithreading

25. Multithreading

26. Multithreading

27. Parallel computing

33. Java & API

34. Java & API

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

36. 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

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 ; } }

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 ; } }

58. 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

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 ; } }

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

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 ; } }

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++ ; } }

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

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() ;

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 ?

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()))) ; } }

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() ; } }

255. Akka actors + STM

256. Akka actors + STM

258. 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 ; } }

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()) ;

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

From Runnable and synchronized To atomically() and parallel()

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