Executors
open class Executors
Factory and utility methods for Executor, ExecutorService, ScheduledExecutorService, ThreadFactory, and Callable classes defined in this package. This class supports the following kinds of methods:
- Methods that create and return an
ExecutorService set up with commonly useful configuration settings.
- Methods that create and return a
ScheduledExecutorService set up with commonly useful configuration settings.
- Methods that create and return a "wrapped" ExecutorService, that disables reconfiguration by making implementation-specific methods inaccessible.
- Methods that create and return a
ThreadFactory that sets newly created threads to a known state.
- Methods that create and return a
Callable out of other closure-like forms, so they can be used in execution methods requiring Callable.
Summary
| Public methods |
| open static Callable<T>! |
Returns a Callable object that, when called, runs the given task and returns the given result.
|
| open static Callable<Any!>! |
Returns a Callable object that, when called, runs the given task and returns null.
|
| open static Callable<Any!>! |
Returns a Callable object that, when called, runs the given privileged action and returns its result.
|
| open static Callable<Any!>! |
Returns a Callable object that, when called, runs the given privileged exception action and returns its result.
|
| open static ThreadFactory! |
Returns a default thread factory used to create new threads.
|
| open static ExecutorService! |
Creates a thread pool that creates new threads as needed, but will reuse previously constructed threads when they are available.
|
| open static ExecutorService! |
Creates a thread pool that creates new threads as needed, but will reuse previously constructed threads when they are available, and uses the provided ThreadFactory to create new threads when needed.
|
| open static ExecutorService! |
Creates a thread pool that reuses a fixed number of threads operating off a shared unbounded queue.
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| open static ExecutorService! |
Creates a thread pool that reuses a fixed number of threads operating off a shared unbounded queue, using the provided ThreadFactory to create new threads when needed.
|
| open static ScheduledExecutorService! |
Creates a thread pool that can schedule commands to run after a given delay, or to execute periodically.
|
| open static ScheduledExecutorService! |
Creates a thread pool that can schedule commands to run after a given delay, or to execute periodically.
|
| open static ExecutorService! |
Creates an Executor that uses a single worker thread operating off an unbounded queue.
|
| open static ExecutorService! |
Creates an Executor that uses a single worker thread operating off an unbounded queue, and uses the provided ThreadFactory to create a new thread when needed.
|
| open static ScheduledExecutorService! |
Creates a single-threaded executor that can schedule commands to run after a given delay, or to execute periodically.
|
| open static ScheduledExecutorService! |
Creates a single-threaded executor that can schedule commands to run after a given delay, or to execute periodically.
|
| open static ExecutorService! |
Creates a thread pool that maintains enough threads to support the given parallelism level, and may use multiple queues to reduce contention.
|
| open static ExecutorService! |
Creates a work-stealing thread pool using the number of Runtime#availableProcessors as its target parallelism level.
|
| open static Callable<T>! |
Legacy security code; do not use.
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| open static Callable<T>! |
Legacy security code; do not use.
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| open static ThreadFactory! |
Legacy security code; do not use.
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| open static ExecutorService! |
Returns an object that delegates all defined ExecutorService methods to the given executor, but not any other methods that might otherwise be accessible using casts.
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| open static ScheduledExecutorService! |
Returns an object that delegates all defined ScheduledExecutorService methods to the given executor, but not any other methods that might otherwise be accessible using casts.
|
Public methods
callable
open static fun <T : Any!> callable(
task: Runnable!,
result: T
): Callable<T>!
Returns a Callable object that, when called, runs the given task and returns the given result. This can be useful when applying methods requiring a Callable to an otherwise resultless action.
| Parameters |
task |
Runnable!: the task to run |
result |
T: the result to return |
<T> |
the type of the result |
| Exceptions |
java.lang.NullPointerException |
if task null |
callable
open static fun callable(task: Runnable!): Callable<Any!>!
Returns a Callable object that, when called, runs the given task and returns null.
| Parameters |
task |
Runnable!: the task to run |
| Exceptions |
java.lang.NullPointerException |
if task null |
callable
open static fun callable(action: PrivilegedAction<*>!): Callable<Any!>!
Returns a Callable object that, when called, runs the given privileged action and returns its result.
| Exceptions |
java.lang.NullPointerException |
if action null |
callable
open static fun callable(action: PrivilegedExceptionAction<*>!): Callable<Any!>!
Returns a Callable object that, when called, runs the given privileged exception action and returns its result.
| Exceptions |
java.lang.NullPointerException |
if action null |
defaultThreadFactory
open static fun defaultThreadFactory(): ThreadFactory!
Returns a default thread factory used to create new threads. This factory creates all new threads used by an Executor in the same ThreadGroup. Each new thread is created as a non-daemon thread with priority set to the smaller of Thread.NORM_PRIORITY and the maximum priority permitted in the thread group. New threads have names accessible via Thread#getName of pool-N-thread-M, where N is the sequence number of this factory, and M is the sequence number of the thread created by this factory.
newCachedThreadPool
open static fun newCachedThreadPool(): ExecutorService!
Creates a thread pool that creates new threads as needed, but will reuse previously constructed threads when they are available. These pools will typically improve the performance of programs that execute many short-lived asynchronous tasks. Calls to execute will reuse previously constructed threads if available. If no existing thread is available, a new thread will be created and added to the pool. Threads that have not been used for sixty seconds are terminated and removed from the cache. Thus, a pool that remains idle for long enough will not consume any resources. Note that pools with similar properties but different details (for example, timeout parameters) may be created using ThreadPoolExecutor constructors.
newCachedThreadPool
open static fun newCachedThreadPool(threadFactory: ThreadFactory!): ExecutorService!
Creates a thread pool that creates new threads as needed, but will reuse previously constructed threads when they are available, and uses the provided ThreadFactory to create new threads when needed.
| Parameters |
threadFactory |
ThreadFactory!: the factory to use when creating new threads |
| Exceptions |
java.lang.NullPointerException |
if threadFactory is null |
newFixedThreadPool
open static fun newFixedThreadPool(nThreads: Int): ExecutorService!
Creates a thread pool that reuses a fixed number of threads operating off a shared unbounded queue. At any point, at most nThreads threads will be active processing tasks. If additional tasks are submitted when all threads are active, they will wait in the queue until a thread is available. If any thread terminates due to a failure during execution prior to shutdown, a new one will take its place if needed to execute subsequent tasks. The threads in the pool will exist until it is explicitly ExecutorService#shutdown.
| Parameters |
nThreads |
Int: the number of threads in the pool |
| Exceptions |
java.lang.IllegalArgumentException |
if nThreads <= 0 |
newFixedThreadPool
open static fun newFixedThreadPool(
nThreads: Int,
threadFactory: ThreadFactory!
): ExecutorService!
Creates a thread pool that reuses a fixed number of threads operating off a shared unbounded queue, using the provided ThreadFactory to create new threads when needed. At any point, at most nThreads threads will be active processing tasks. If additional tasks are submitted when all threads are active, they will wait in the queue until a thread is available. If any thread terminates due to a failure during execution prior to shutdown, a new one will take its place if needed to execute subsequent tasks. The threads in the pool will exist until it is explicitly ExecutorService#shutdown.
| Parameters |
nThreads |
Int: the number of threads in the pool |
threadFactory |
ThreadFactory!: the factory to use when creating new threads |
| Exceptions |
java.lang.NullPointerException |
if threadFactory is null |
java.lang.IllegalArgumentException |
if nThreads <= 0 |
newScheduledThreadPool
open static fun newScheduledThreadPool(corePoolSize: Int): ScheduledExecutorService!
Creates a thread pool that can schedule commands to run after a given delay, or to execute periodically.
| Parameters |
corePoolSize |
Int: the number of threads to keep in the pool, even if they are idle |
| Exceptions |
java.lang.IllegalArgumentException |
if corePoolSize < 0 |
newScheduledThreadPool
open static fun newScheduledThreadPool(
corePoolSize: Int,
threadFactory: ThreadFactory!
): ScheduledExecutorService!
Creates a thread pool that can schedule commands to run after a given delay, or to execute periodically.
| Parameters |
corePoolSize |
Int: the number of threads to keep in the pool, even if they are idle |
threadFactory |
ThreadFactory!: the factory to use when the executor creates a new thread |
| Exceptions |
java.lang.IllegalArgumentException |
if corePoolSize < 0 |
java.lang.NullPointerException |
if threadFactory is null |
newSingleThreadExecutor
open static fun newSingleThreadExecutor(): ExecutorService!
Creates an Executor that uses a single worker thread operating off an unbounded queue. (Note however that if this single thread terminates due to a failure during execution prior to shutdown, a new one will take its place if needed to execute subsequent tasks.) Tasks are guaranteed to execute sequentially, and no more than one task will be active at any given time. Unlike the otherwise equivalent newFixedThreadPool(1) the returned executor is guaranteed not to be reconfigurable to use additional threads.
newSingleThreadExecutor
open static fun newSingleThreadExecutor(threadFactory: ThreadFactory!): ExecutorService!
Creates an Executor that uses a single worker thread operating off an unbounded queue, and uses the provided ThreadFactory to create a new thread when needed. Unlike the otherwise equivalent newFixedThreadPool(1, threadFactory) the returned executor is guaranteed not to be reconfigurable to use additional threads.
| Parameters |
threadFactory |
ThreadFactory!: the factory to use when creating new threads |
| Exceptions |
java.lang.NullPointerException |
if threadFactory is null |
newSingleThreadScheduledExecutor
open static fun newSingleThreadScheduledExecutor(): ScheduledExecutorService!
Creates a single-threaded executor that can schedule commands to run after a given delay, or to execute periodically. (Note however that if this single thread terminates due to a failure during execution prior to shutdown, a new one will take its place if needed to execute subsequent tasks.) Tasks are guaranteed to execute sequentially, and no more than one task will be active at any given time. Unlike the otherwise equivalent newScheduledThreadPool(1) the returned executor is guaranteed not to be reconfigurable to use additional threads.
newSingleThreadScheduledExecutor
open static fun newSingleThreadScheduledExecutor(threadFactory: ThreadFactory!): ScheduledExecutorService!
Creates a single-threaded executor that can schedule commands to run after a given delay, or to execute periodically. (Note however that if this single thread terminates due to a failure during execution prior to shutdown, a new one will take its place if needed to execute subsequent tasks.) Tasks are guaranteed to execute sequentially, and no more than one task will be active at any given time. Unlike the otherwise equivalent newScheduledThreadPool(1, threadFactory) the returned executor is guaranteed not to be reconfigurable to use additional threads.
| Parameters |
threadFactory |
ThreadFactory!: the factory to use when creating new threads |
| Exceptions |
java.lang.NullPointerException |
if threadFactory is null |
newWorkStealingPool
open static fun newWorkStealingPool(parallelism: Int): ExecutorService!
Creates a thread pool that maintains enough threads to support the given parallelism level, and may use multiple queues to reduce contention. The parallelism level corresponds to the maximum number of threads actively engaged in, or available to engage in, task processing. The actual number of threads may grow and shrink dynamically. A work-stealing pool makes no guarantees about the order in which submitted tasks are executed.
| Parameters |
parallelism |
Int: the targeted parallelism level |
| Exceptions |
java.lang.IllegalArgumentException |
if parallelism <= 0 |
privilegedCallable
open static fun <T : Any!> privilegedCallable(callable: Callable<T>!): Callable<T>!
Legacy security code; do not use.
privilegedCallableUsingCurrentClassLoader
open static fun <T : Any!> privilegedCallableUsingCurrentClassLoader(callable: Callable<T>!): Callable<T>!
Legacy security code; do not use.
privilegedThreadFactory
open static fun privilegedThreadFactory(): ThreadFactory!
Legacy security code; do not use.
unconfigurableExecutorService
open static fun unconfigurableExecutorService(executor: ExecutorService!): ExecutorService!
Returns an object that delegates all defined ExecutorService methods to the given executor, but not any other methods that might otherwise be accessible using casts. This provides a way to safely "freeze" configuration and disallow tuning of a given concrete implementation.
| Exceptions |
java.lang.NullPointerException |
if executor null |
unconfigurableScheduledExecutorService
open static fun unconfigurableScheduledExecutorService(executor: ScheduledExecutorService!): ScheduledExecutorService!
Returns an object that delegates all defined ScheduledExecutorService methods to the given executor, but not any other methods that might otherwise be accessible using casts. This provides a way to safely "freeze" configuration and disallow tuning of a given concrete implementation.
| Exceptions |
java.lang.NullPointerException |
if executor null |
