--- intro.html 2002/12/08 20:28:28 1.3 +++ intro.html 2002/12/10 11:40:48 1.4 @@ -33,9 +33,9 @@ conservative in selecting only those APIs and implementations that are useful enough to encourage nearly all concurrent programmers to use routinely. JSR 166 also includes a few changes and additions in -packages outside of java.util.concurrent: java.lang, to address timing -and uncaught exceptions, and java.util to better integrate queues, and -to make Timers conform to new frameworks. The API covers: +packages outside of java.util.concurrent: java.lang, to address +uncaught exceptions, and java.util to better integrate queues. +The API covers: @@ -77,16 +77,16 @@ java.util.LinkedList will be adapted to support Queue, and a new non-thread-safe java.util.HeapPriorityQueue will be added. -

-Four implementations in java.util.concurrent support the extended +

Five implementations in java.util.concurrent support the extended BlockingQueue interface, that defines blocking versions of put and -take: LinkedBlockingQueue, ArrayBlockingQueue, SynchronousQueue, and -PriorityBlockingQueue. Additionally, java.util.concurrent.LinkedQueue -supplies an efficient thread-safe non-blocking queue. -

-Since the target release is JDK1.5, and generics are slated to be in -1.5, Queues should be parametrized on element type. (Also some others -below.) We are ignoring this for now. +take: LinkedBlockingQueue, ArrayBlockingQueue, SynchronousQueue, +PriorityBlockingQueue, and DelayQueue. Additionally, +java.util.concurrent.LinkedQueue supplies an efficient thread-safe +non-blocking queue. + +

Since the target release is JDK1.5, and generics are slated to be +in 1.5, Queues are parametrized on element type. (Also some others +below.)

Executors

@@ -95,7 +95,7 @@ thread-like subsystems, including thread pools, asynch-IO, and lightweight task frameworks. Executors also standardize ways of calling threads that compute functions returning results, via -Futures. This is supported in part by defining java.lang.Callable, the +Futures. This is supported in part by defining interface Callable, the argument/result analog of Runnable.

While the Executor framework is intended to be extensible the most @@ -105,10 +105,6 @@ majority of usages, even sophisticated ones, yet also includes methods and functionality that simplify routine usage. -

-A few methods will also be added to the java.util.Timer to support -Futures, and address other requests for enhancement. -

Locks

The Lock interface supports locking disciplines that differ in @@ -166,25 +162,26 @@ Java has always supported sub-millisecond versions of several native time-out-based methods (such as Object.wait), but not methods to actually perform timing in finer-grained units. We address this by -introducing java.lang.Clock, which provides multiple granularities for +introducing class Clock, which provides multiple granularities for both accessing time and performing time-out based operations. -

Barriers

+

Synchronizers

-Barriers (multiway synchronization points) are very common in some -styles of parallel programming, yet tricky to get right. The two most -useful flavors (CyclicBarriers and Exchangers) don't have much of an -interface in common, and only have one standard implementation each, -so these are simply defined as public classes rather than interfaces -and implementations. +Five classes aid common special-purpose synchronization idioms. +Semaphores and FifoSemaphores are classic concurrency tools. Latches +are very simple yet very common objects useful for blocking until a +single signal, event, or condition holds. CyclicBarriers are +resettable multiway synchronization points very common in some styles +of parallel programming. Exchangers allow two threads to exchange +objects at a rendezvous point.

Concurrent Collections

-There are no new interfaces, but JSR 166 will supply a few Collection -implementations designed for use in multithreaded contexts: -ConcurrentHashTable, CopyOnWriteArrayList, and CopyOnWriteArraySet. +JSR 166 will supply a few Collection implementations designed for use +in multithreaded contexts: ConcurrentHashTable, CopyOnWriteArrayList, +and CopyOnWriteArraySet.

Uncaught Exception Handlers

@@ -195,8 +192,8 @@ of features in JSR 166 make ThreadGroups even less likely to be used in most programs. Perhaps they will eventually be deprecated.)

-Additionally, Threads and ThreadLocals will now support a means to -clear and remove ThreadLocals, which is needed in some thread-pool and +Additionally, ThreadLocals will now support a means to +remove a ThreadLocals, which is needed in some thread-pool and worker-thread designs.