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FlexDoc/Javadoc 2.0 Demo Java Doc |
Implementations. Classes ThreadPoolExecutor and ScheduledThreadPoolExecutor provide tunable, flexible thread pools. The Executors class provides factory methods for the most common kinds and configurations of Executors, as well as a few utility methods for using them. Other utilities based on Executors include the concrete class FutureTask providing a common extensible implementation of Futures, and ExecutorCompletionService, that assists in coordinating the processing of groups of asynchronous tasks.
Class ForkJoinPool provides an Executor primarily designed for processing instances of ForkJoinTask and its subclasses. These classes employ a work-stealing scheduler that attains high throughput for tasks conforming to restrictions that often hold in computation-intensive parallel processing.
Five implementations in java.util.concurrent support the extended BlockingQueue interface, that defines blocking versions of put and take: LinkedBlockingQueue, ArrayBlockingQueue, SynchronousQueue, PriorityBlockingQueue, and DelayQueue. The different classes cover the most common usage contexts for producer-consumer, messaging, parallel tasking, and related concurrent designs.
Extended interface TransferQueue, and implementation LinkedTransferQueue introduce a synchronous transfer method (along with related features) in which a producer may optionally block awaiting its consumer.
The BlockingDeque interface extends BlockingQueue to support both FIFO and LIFO (stack-based) operations. Class LinkedBlockingDeque provides an implementation.
The "Concurrent" prefix used with some classes in this package is a shorthand indicating several differences from similar "synchronized" classes. For example java.util.Hashtable and Collections.synchronizedMap(new HashMap()) are synchronized. But ConcurrentHashMap is "concurrent". A concurrent collection is thread-safe, but not governed by a single exclusion lock. In the particular case of ConcurrentHashMap, it safely permits any number of concurrent reads as well as a large number of concurrent writes. "Synchronized" classes can be useful when you need to prevent all access to a collection via a single lock, at the expense of poorer scalability. In other cases in which multiple threads are expected to access a common collection, "concurrent" versions are normally preferable. And unsynchronized collections are preferable when either collections are unshared, or are accessible only when holding other locks.
Most concurrent Collection implementations (including most Queues) also differ from the usual java.util conventions in that their Iterators and Spliterators provide weakly consistent rather than fast-fail traversal:
Interface Summary |
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A Deque that additionally supports blocking operations that wait
for the deque to become non-empty when retrieving an element, and wait for
space to become available in the deque when storing an element. |
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A Queue that additionally supports operations that wait for
the queue to become non-empty when retrieving an element, and wait
for space to become available in the queue when storing an element. |
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A task that returns a result and may throw an exception. |
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A marker interface identifying asynchronous tasks produced by
async methods. |
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A service that decouples the production of new asynchronous tasks
from the consumption of the results of completed tasks. |
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A stage of a possibly asynchronous computation, that performs an
action or computes a value when another CompletionStage completes. |
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A Map providing thread safety and atomicity guarantees. |
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A ConcurrentMap supporting NavigableMap operations,
and recursively so for its navigable sub-maps. |
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A mix-in style interface for marking objects that should be
acted upon after a given delay. |
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An object that executes submitted Runnable tasks. |
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A component that acts as both a Subscriber and Publisher. |
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A producer of items (and related control messages) received by
Subscribers. |
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A receiver of messages. |
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Message control linking a Flow.Publisher and Flow.Subscriber. |
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Factory for creating new ForkJoinWorkerThreads. |
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Interface for extending managed parallelism for tasks running
in ForkJoinPools. |
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A Future represents the result of an asynchronous
computation. |
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A handler for tasks that cannot be executed by a ThreadPoolExecutor. |
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A ScheduledFuture that is Runnable. |
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An ExecutorService that can schedule commands to run after a given
delay, or to execute periodically. |
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A delayed result-bearing action that can be cancelled. |
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An object that creates new threads on demand. |
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A BlockingQueue in which producers may wait for consumers
to receive elements. |
Class Summary |
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Provides default implementations of ExecutorService
execution methods. |
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A bounded blocking queue backed by an
array. |
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A Future that may be explicitly completed (setting its
value and status), and may be used as a CompletionStage,
supporting dependent functions and actions that trigger upon its
completion. |
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A hash table supporting full concurrency of retrievals and
high expected concurrency for updates. |
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A view of a ConcurrentHashMap as a Set of keys, in
which additions may optionally be enabled by mapping to a
common value. |
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An unbounded concurrent deque based on linked nodes. |
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An unbounded thread-safe queue based on linked nodes. |
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A scalable concurrent ConcurrentNavigableMap implementation. |
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A scalable concurrent NavigableSet implementation based on
a ConcurrentSkipListMap. |
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A thread-safe variant of ArrayList in which all mutative
operations (add, set, and so on) are implemented by
making a fresh copy of the underlying array. |
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A Set that uses an internal CopyOnWriteArrayList
for all of its operations. |
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A synchronization aid that allows one or more threads to wait until
a set of operations being performed in other threads completes. |
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A ForkJoinTask with a completion action performed when
triggered and there are no remaining pending actions. |
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A synchronization aid that allows a set of threads to all wait for
each other to reach a common barrier point. |
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An unbounded blocking queue of
Delayed elements, in which an element can only be taken
when its delay has expired. |
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A synchronization point at which threads can pair and swap elements
within pairs. |
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A CompletionService that uses a supplied Executor
to execute tasks. |
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Factory and utility methods for Executor, ExecutorService, ScheduledExecutorService, ThreadFactory, and Callable classes defined in this
package. |
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Interrelated interfaces and static methods for establishing
flow-controlled components in which Publishers
produce items consumed by one or more Subscribers, each managed by a Subscription. |
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An ExecutorService for running ForkJoinTasks. |
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Abstract base class for tasks that run within a ForkJoinPool. |
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A thread managed by a ForkJoinPool, which executes
ForkJoinTasks. |
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A cancellable asynchronous computation. |
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An optionally-bounded blocking deque based on
linked nodes. |
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An optionally-bounded blocking queue based on
linked nodes. |
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An unbounded TransferQueue based on linked nodes. |
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A reusable synchronization barrier, similar in functionality to
CyclicBarrier and CountDownLatch but supporting
more flexible usage. |
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An unbounded blocking queue that uses
the same ordering rules as class PriorityQueue and supplies
blocking retrieval operations. |
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A recursive resultless ForkJoinTask. |
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A recursive result-bearing ForkJoinTask. |
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A ThreadPoolExecutor that can additionally schedule
commands to run after a given delay, or to execute periodically. |
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A counting semaphore. |
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A Flow.Publisher that asynchronously issues submitted
(non-null) items to current subscribers until it is closed. |
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A blocking queue in which each insert
operation must wait for a corresponding remove operation by another
thread, and vice versa. |
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A random number generator (with period 264) isolated
to the current thread. |
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An ExecutorService that executes each submitted task using
one of possibly several pooled threads, normally configured
using Executors factory methods. |
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A handler for rejected tasks that throws a
RejectedExecutionException. |
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A handler for rejected tasks that runs the rejected task
directly in the calling thread of the execute method,
unless the executor has been shut down, in which case the task
is discarded. |
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A handler for rejected tasks that discards the oldest unhandled
request and then retries execute, unless the executor
is shut down, in which case the task is discarded. |
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A handler for rejected tasks that silently discards the
rejected task. |
Enum Summary |
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A TimeUnit represents time durations at a given unit of
granularity and provides utility methods to convert across units,
and to perform timing and delay operations in these units. |
Exception Summary |
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Exception thrown when a thread tries to wait upon a barrier that is
in a broken state, or which enters the broken state while the thread
is waiting. |
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Exception indicating that the result of a value-producing task,
such as a FutureTask, cannot be retrieved because the task
was cancelled. |
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Exception thrown when an error or other exception is encountered
in the course of completing a result or task. |
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Exception thrown when attempting to retrieve the result of a task
that aborted by throwing an exception. |
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Exception thrown by an Executor when a task cannot be
accepted for execution. |
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Exception thrown when a blocking operation times out. |
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FlexDoc/Javadoc 2.0 Demo Java Doc |