concurrencyproblem

Concurrency ProblemAdriano Patrick Cunha - UDCE

quarta-feira, 10 de outubro de 2012

Evolution of processors


Big Data to process


What Possibilities ?


Concurrence?


Which options ?


Functional Programming language ?


5

API java.util.concurrent


Thead-Safe


Thead-Safe

private Set<String> ipAddressSet = new HashSet<String>();


Thead-Safe

private Set<String> ipAddressSet = new HashSet<String>(); private Set<String> ipAddressSet = Collections.

synchonizedSet(new HashSet<String>());


Thead-Safe



private BlockingQueue<String> ipAddress=new LinkedBlockingQueue<String>();


Thead-Safe



private BlockingQueue<String> ipAddress=new LinkedBlockingQueue<String>();

fast-fail iterators

weakly consistent iterators


Thead-Safe

ConcurrentHashMap, CopyOnWriteArrayList e CopyOnWriteArraySet

Outras Coleções


Executor

Executor

ExecutorServiceScheduledExecutorService


Executor

(new Thread(r)).start();


Executor

(new Thread(r)).start();e.execute(r);


Thread Pools

Executors.newCachedThreadPool();

Executors.newFixedThreadPoll(n);

Executors.newSingleThreadExecutor();


class Counter { private int c = 0;

public void increment() { c++; }

public void decrement() { c--; }

public int value() { return c; }

}

1. Retrieve the current value of c.2. Increment the retrieved value by 1.3. Store the incremented value back in c.

1. Thread A: Retrieve c.2. Thread B: Retrieve c.3. Thread A: Increment retrieved value; result is 1.4. Thread B: Decrement retrieved value; result is -1.5. Thread A: Store result in c; c is now 1.6. Thread B: Store result in c; c is now -1.

Thread Pools


class SynchronizedCounter { private int c = 0;

public synchronized void increment() { c++; }

public synchronized void decrement() { c--; }

public synchronized int value() { return c; }

}

Thread Pools


Thread Pools

import java.util.concurrent.atomic.AtomicInteger;

class AtomicCounter { private AtomicInteger c = new AtomicInteger(0);

public void increment() { c.incrementAndGet(); }

public void decrement() { c.decrementAndGet(); }

public int value() { return c.get(); }

}


Bibliografia

Livros

Concurrent Programming in Java, Design Principles and Patterns, Doug Lea, Addison-Wesley, 1999

Java Concurrency In Practice, Brian Goetz, Addison-Wesley, 2006

Links

http://docs.oracle.com/javase/tutorial/essential/concurrency/index.html

http://www.jcp.org/en/jsr/detail?id=166

http://gee.cs.oswego.edu/dl/concurrency-interest/

http://www.devmedia.com.br/websys.2/webreader.asp?cat=6&revista=javamagazine_69








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