- ->thread-pool-executor
- allow-core-thread-time-out
- allows-core-thread-time-out
- await-termination
- execute
- get-active-count
- get-completed-task-count
- get-core-pool-size
- get-keep-alive-time
- get-largest-pool-size
- get-maximum-pool-size
- get-pool-size
- get-queue
- get-rejected-execution-handler
- get-task-count
- get-thread-factory
- prestart-all-core-threads
- prestart-core-thread
- purge
- remove
- set-core-pool-size
- set-keep-alive-time
- set-maximum-pool-size
- set-rejected-execution-handler
- set-thread-factory
- shutdown
- shutdown-now
- shutdown?
- terminated?
- terminating?
- to-string
jdk.util.concurrent.ThreadPoolExecutor
An ExecutorService that executes each submitted task using one of possibly several pooled threads, normally configured using Executors factory methods.
Thread pools address two different problems: they usually provide improved performance when executing large numbers of asynchronous tasks, due to reduced per-task invocation overhead, and they provide a means of bounding and managing the resources, including threads, consumed when executing a collection of tasks. Each ThreadPoolExecutor also maintains some basic statistics, such as the number of completed tasks.
To be useful across a wide range of contexts, this class provides many adjustable parameters and extensibility hooks. However, programmers are urged to use the more convenient Executors factory methods Executors.newCachedThreadPool() (unbounded thread pool, with automatic thread reclamation), Executors.newFixedThreadPool(int) (fixed size thread pool) and Executors.newSingleThreadExecutor() (single background thread), that preconfigure settings for the most common usage scenarios. Otherwise, use the following guide when manually configuring and tuning this class:
Core and maximum pool sizes
A ThreadPoolExecutor will automatically adjust the pool size (see getPoolSize()) according to the bounds set by corePoolSize (see getCorePoolSize()) and maximumPoolSize (see getMaximumPoolSize()).
When a new task is submitted in method execute(Runnable), and fewer than corePoolSize threads are running, a new thread is created to handle the request, even if other worker threads are idle. If there are more than corePoolSize but less than maximumPoolSize threads running, a new thread will be created only if the queue is full. By setting corePoolSize and maximumPoolSize the same, you create a fixed-size thread pool. By setting maximumPoolSize to an essentially unbounded value such as Integer.MAX_VALUE, you allow the pool to accommodate an arbitrary number of concurrent tasks. Most typically, core and maximum pool sizes are set only upon construction, but they may also be changed dynamically using setCorePoolSize(int) and setMaximumPoolSize(int).
On-demand construction
By default, even core threads are initially created and started only when new tasks arrive, but this can be overridden dynamically using method prestartCoreThread() or prestartAllCoreThreads(). You probably want to prestart threads if you construct the pool with a non-empty queue.
Creating new threads
New threads are created using a ThreadFactory. If not otherwise specified, a Executors.defaultThreadFactory() is used, that creates threads to all be in the same ThreadGroup and with the same NORM_PRIORITY priority and non-daemon status. By supplying a different ThreadFactory, you can alter the thread's name, thread group, priority, daemon status, etc. If a ThreadFactory fails to create a thread when asked by returning null from newThread, the executor will continue, but might not be able to execute any tasks. Threads should possess the "modifyThread" RuntimePermission. If worker threads or other threads using the pool do not possess this permission, service may be degraded: configuration changes may not take effect in a timely manner, and a shutdown pool may remain in a state in which termination is possible but not completed.
Keep-alive times
If the pool currently has more than corePoolSize threads, excess threads will be terminated if they have been idle for more than the keepAliveTime (see getKeepAliveTime(TimeUnit)). This provides a means of reducing resource consumption when the pool is not being actively used. If the pool becomes more active later, new threads will be constructed. This parameter can also be changed dynamically using method setKeepAliveTime(long, TimeUnit). Using a value of Long.MAX_VALUE TimeUnit.NANOSECONDS effectively disables idle threads from ever terminating prior to shut down. By default, the keep-alive policy applies only when there are more than corePoolSize threads. But method allowCoreThreadTimeOut(boolean) can be used to apply this time-out policy to core threads as well, so long as the keepAliveTime value is non-zero.
Queuing
Any BlockingQueue may be used to transfer and hold submitted tasks. The use of this queue interacts with pool sizing:
If fewer than corePoolSize threads are running, the Executor always prefers adding a new thread rather than queuing.
If corePoolSize or more threads are running, the Executor always prefers queuing a request rather than adding a new thread.
If a request cannot be queued, a new thread is created unless this would exceed maximumPoolSize, in which case, the task will be rejected.
There are three general strategies for queuing:
Direct handoffs. A good default choice for a work queue is a SynchronousQueue that hands off tasks to threads without otherwise holding them. Here, an attempt to queue a task will fail if no threads are immediately available to run it, so a new thread will be constructed. This policy avoids lockups when handling sets of requests that might have internal dependencies. Direct handoffs generally require unbounded maximumPoolSizes to avoid rejection of new submitted tasks. This in turn admits the possibility of unbounded thread growth when commands continue to arrive on average faster than they can be processed.
Unbounded queues. Using an unbounded queue (for example a LinkedBlockingQueue without a predefined capacity) will cause new tasks to wait in the queue when all corePoolSize threads are busy. Thus, no more than corePoolSize threads will ever be created. (And the value of the maximumPoolSize therefore doesn't have any effect.) This may be appropriate when each task is completely independent of others, so tasks cannot affect each others execution; for example, in a web page server. While this style of queuing can be useful in smoothing out transient bursts of requests, it admits the possibility of unbounded work queue growth when commands continue to arrive on average faster than they can be processed.
Bounded queues. A bounded queue (for example, an ArrayBlockingQueue) helps prevent resource exhaustion when used with finite maximumPoolSizes, but can be more difficult to tune and control. Queue sizes and maximum pool sizes may be traded off for each other: Using large queues and small pools minimizes CPU usage, OS resources, and context-switching overhead, but can lead to artificially low throughput. If tasks frequently block (for example if they are I/O bound), a system may be able to schedule time for more threads than you otherwise allow. Use of small queues generally requires larger pool sizes, which keeps CPUs busier but may encounter unacceptable scheduling overhead, which also decreases throughput.
Rejected tasks
New tasks submitted in method execute(Runnable) will be rejected when the Executor has been shut down, and also when the Executor uses finite bounds for both maximum threads and work queue capacity, and is saturated. In either case, the execute method invokes the RejectedExecutionHandler.rejectedExecution(Runnable, ThreadPoolExecutor) method of its RejectedExecutionHandler. Four predefined handler policies are provided:
In the default ThreadPoolExecutor.AbortPolicy, the handler throws a runtime RejectedExecutionException upon rejection.
In ThreadPoolExecutor.CallerRunsPolicy, the thread that invokes execute itself runs the task. This provides a simple feedback control mechanism that will slow down the rate that new tasks are submitted.
In ThreadPoolExecutor.DiscardPolicy, a task that cannot be executed is simply dropped.
In ThreadPoolExecutor.DiscardOldestPolicy, if the executor is not shut down, the task at the head of the work queue is dropped, and then execution is retried (which can fail again, causing this to be repeated.)
It is possible to define and use other kinds of RejectedExecutionHandler classes. Doing so requires some care especially when policies are designed to work only under particular capacity or queuing policies.
Hook methods
This class provides protected overridable beforeExecute(Thread, Runnable) and afterExecute(Runnable, Throwable) methods that are called before and after execution of each task. These can be used to manipulate the execution environment; for example, reinitializing ThreadLocals, gathering statistics, or adding log entries. Additionally, method terminated() can be overridden to perform any special processing that needs to be done once the Executor has fully terminated.
If hook or callback methods throw exceptions, internal worker threads may in turn fail and abruptly terminate.
Queue maintenance
Method getQueue() allows access to the work queue for purposes of monitoring and debugging. Use of this method for any other purpose is strongly discouraged. Two supplied methods, remove(Runnable) and purge() are available to assist in storage reclamation when large numbers of queued tasks become cancelled.
Finalization
A pool that is no longer referenced in a program AND has no remaining threads will be shutdown automatically. If you would like to ensure that unreferenced pools are reclaimed even if users forget to call shutdown(), then you must arrange that unused threads eventually die, by setting appropriate keep-alive times, using a lower bound of zero core threads and/or setting allowCoreThreadTimeOut(boolean).
Extension example. Most extensions of this class override one or more of the protected hook methods. For example, here is a subclass that adds a simple pause/resume feature:
class PausableThreadPoolExecutor extends ThreadPoolExecutor { private boolean isPaused; private ReentrantLock pauseLock = new ReentrantLock(); private Condition unpaused = pauseLock.newCondition();
public PausableThreadPoolExecutor(...) { super(...); }
protected void beforeExecute(Thread t, Runnable r) { super.beforeExecute(t, r); pauseLock.lock(); try { while (isPaused) unpaused.await(); } catch (InterruptedException ie) { t.interrupt(); } finally { pauseLock.unlock(); } }
public void pause() { pauseLock.lock(); try { isPaused = true; } finally { pauseLock.unlock(); } }
public void resume() { pauseLock.lock(); try { isPaused = false; unpaused.signalAll(); } finally { pauseLock.unlock(); } } }
An ExecutorService that executes each submitted task using
one of possibly several pooled threads, normally configured
using Executors factory methods.
Thread pools address two different problems: they usually
provide improved performance when executing large numbers of
asynchronous tasks, due to reduced per-task invocation overhead,
and they provide a means of bounding and managing the resources,
including threads, consumed when executing a collection of tasks.
Each ThreadPoolExecutor also maintains some basic
statistics, such as the number of completed tasks.
To be useful across a wide range of contexts, this class
provides many adjustable parameters and extensibility
hooks. However, programmers are urged to use the more convenient
Executors factory methods Executors.newCachedThreadPool() (unbounded thread pool, with
automatic thread reclamation), Executors.newFixedThreadPool(int)
(fixed size thread pool) and Executors.newSingleThreadExecutor() (single background thread), that
preconfigure settings for the most common usage
scenarios. Otherwise, use the following guide when manually
configuring and tuning this class:
Core and maximum pool sizes
A ThreadPoolExecutor will automatically adjust the
pool size (see getPoolSize())
according to the bounds set by
corePoolSize (see getCorePoolSize()) and
maximumPoolSize (see getMaximumPoolSize()).
When a new task is submitted in method execute(Runnable),
and fewer than corePoolSize threads are running, a new thread is
created to handle the request, even if other worker threads are
idle. If there are more than corePoolSize but less than
maximumPoolSize threads running, a new thread will be created only
if the queue is full. By setting corePoolSize and maximumPoolSize
the same, you create a fixed-size thread pool. By setting
maximumPoolSize to an essentially unbounded value such as Integer.MAX_VALUE, you allow the pool to accommodate an arbitrary
number of concurrent tasks. Most typically, core and maximum pool
sizes are set only upon construction, but they may also be changed
dynamically using setCorePoolSize(int) and setMaximumPoolSize(int).
On-demand construction
By default, even core threads are initially created and
started only when new tasks arrive, but this can be overridden
dynamically using method prestartCoreThread() or prestartAllCoreThreads(). You probably want to prestart threads if
you construct the pool with a non-empty queue.
Creating new threads
New threads are created using a ThreadFactory. If not
otherwise specified, a Executors.defaultThreadFactory() is
used, that creates threads to all be in the same ThreadGroup and with the same NORM_PRIORITY priority and
non-daemon status. By supplying a different ThreadFactory, you can
alter the thread's name, thread group, priority, daemon status,
etc. If a ThreadFactory fails to create a thread when asked
by returning null from newThread, the executor will
continue, but might not be able to execute any tasks. Threads
should possess the "modifyThread" RuntimePermission. If
worker threads or other threads using the pool do not possess this
permission, service may be degraded: configuration changes may not
take effect in a timely manner, and a shutdown pool may remain in a
state in which termination is possible but not completed.
Keep-alive times
If the pool currently has more than corePoolSize threads,
excess threads will be terminated if they have been idle for more
than the keepAliveTime (see getKeepAliveTime(TimeUnit)).
This provides a means of reducing resource consumption when the
pool is not being actively used. If the pool becomes more active
later, new threads will be constructed. This parameter can also be
changed dynamically using method setKeepAliveTime(long,
TimeUnit). Using a value of Long.MAX_VALUE TimeUnit.NANOSECONDS effectively disables idle threads from ever
terminating prior to shut down. By default, the keep-alive policy
applies only when there are more than corePoolSize threads. But
method allowCoreThreadTimeOut(boolean) can be used to
apply this time-out policy to core threads as well, so long as the
keepAliveTime value is non-zero.
Queuing
Any BlockingQueue may be used to transfer and hold
submitted tasks. The use of this queue interacts with pool sizing:
If fewer than corePoolSize threads are running, the Executor
always prefers adding a new thread
rather than queuing.
If corePoolSize or more threads are running, the Executor
always prefers queuing a request rather than adding a new
thread.
If a request cannot be queued, a new thread is created unless
this would exceed maximumPoolSize, in which case, the task will be
rejected.
There are three general strategies for queuing:
Direct handoffs. A good default choice for a work
queue is a SynchronousQueue that hands off tasks to threads
without otherwise holding them. Here, an attempt to queue a task
will fail if no threads are immediately available to run it, so a
new thread will be constructed. This policy avoids lockups when
handling sets of requests that might have internal dependencies.
Direct handoffs generally require unbounded maximumPoolSizes to
avoid rejection of new submitted tasks. This in turn admits the
possibility of unbounded thread growth when commands continue to
arrive on average faster than they can be processed.
Unbounded queues. Using an unbounded queue (for
example a LinkedBlockingQueue without a predefined
capacity) will cause new tasks to wait in the queue when all
corePoolSize threads are busy. Thus, no more than corePoolSize
threads will ever be created. (And the value of the maximumPoolSize
therefore doesn't have any effect.) This may be appropriate when
each task is completely independent of others, so tasks cannot
affect each others execution; for example, in a web page server.
While this style of queuing can be useful in smoothing out
transient bursts of requests, it admits the possibility of
unbounded work queue growth when commands continue to arrive on
average faster than they can be processed.
Bounded queues. A bounded queue (for example, an
ArrayBlockingQueue) helps prevent resource exhaustion when
used with finite maximumPoolSizes, but can be more difficult to
tune and control. Queue sizes and maximum pool sizes may be traded
off for each other: Using large queues and small pools minimizes
CPU usage, OS resources, and context-switching overhead, but can
lead to artificially low throughput. If tasks frequently block (for
example if they are I/O bound), a system may be able to schedule
time for more threads than you otherwise allow. Use of small queues
generally requires larger pool sizes, which keeps CPUs busier but
may encounter unacceptable scheduling overhead, which also
decreases throughput.
Rejected tasks
New tasks submitted in method execute(Runnable) will be
rejected when the Executor has been shut down, and also when
the Executor uses finite bounds for both maximum threads and work queue
capacity, and is saturated. In either case, the execute method
invokes the RejectedExecutionHandler.rejectedExecution(Runnable, ThreadPoolExecutor)
method of its RejectedExecutionHandler. Four predefined handler
policies are provided:
In the default ThreadPoolExecutor.AbortPolicy, the
handler throws a runtime RejectedExecutionException upon
rejection.
In ThreadPoolExecutor.CallerRunsPolicy, the thread
that invokes execute itself runs the task. This provides a
simple feedback control mechanism that will slow down the rate that
new tasks are submitted.
In ThreadPoolExecutor.DiscardPolicy, a task that
cannot be executed is simply dropped.
In ThreadPoolExecutor.DiscardOldestPolicy, if the
executor is not shut down, the task at the head of the work queue
is dropped, and then execution is retried (which can fail again,
causing this to be repeated.)
It is possible to define and use other kinds of RejectedExecutionHandler classes. Doing so requires some care
especially when policies are designed to work only under particular
capacity or queuing policies.
Hook methods
This class provides protected overridable
beforeExecute(Thread, Runnable) and
afterExecute(Runnable, Throwable) methods that are called
before and after execution of each task. These can be used to
manipulate the execution environment; for example, reinitializing
ThreadLocals, gathering statistics, or adding log entries.
Additionally, method terminated() can be overridden to perform
any special processing that needs to be done once the Executor has
fully terminated.
If hook or callback methods throw exceptions, internal worker
threads may in turn fail and abruptly terminate.
Queue maintenance
Method getQueue() allows access to the work queue
for purposes of monitoring and debugging. Use of this method for
any other purpose is strongly discouraged. Two supplied methods,
remove(Runnable) and purge() are available to
assist in storage reclamation when large numbers of queued tasks
become cancelled.
Finalization
A pool that is no longer referenced in a program AND
has no remaining threads will be shutdown automatically. If
you would like to ensure that unreferenced pools are reclaimed even
if users forget to call shutdown(), then you must arrange
that unused threads eventually die, by setting appropriate
keep-alive times, using a lower bound of zero core threads and/or
setting allowCoreThreadTimeOut(boolean).
Extension example. Most extensions of this class
override one or more of the protected hook methods. For example,
here is a subclass that adds a simple pause/resume feature:
class PausableThreadPoolExecutor extends ThreadPoolExecutor {
private boolean isPaused;
private ReentrantLock pauseLock = new ReentrantLock();
private Condition unpaused = pauseLock.newCondition();
public PausableThreadPoolExecutor(...) { super(...); }
protected void beforeExecute(Thread t, Runnable r) {
super.beforeExecute(t, r);
pauseLock.lock();
try {
while (isPaused) unpaused.await();
} catch (InterruptedException ie) {
t.interrupt();
} finally {
pauseLock.unlock();
}
}
public void pause() {
pauseLock.lock();
try {
isPaused = true;
} finally {
pauseLock.unlock();
}
}
public void resume() {
pauseLock.lock();
try {
isPaused = false;
unpaused.signalAll();
} finally {
pauseLock.unlock();
}
}
}->thread-pool-executorclj
(->thread-pool-executor core-pool-size
maximum-pool-size
keep-alive-time
unit
work-queue)(->thread-pool-executor core-pool-size
maximum-pool-size
keep-alive-time
unit
work-queue
thread-factory)(->thread-pool-executor core-pool-size
maximum-pool-size
keep-alive-time
unit
work-queue
thread-factory
handler)Constructor.
Creates a new ThreadPoolExecutor with the given initial parameters.
core-pool-size - the number of threads to keep in the pool, even if they are idle, unless allowCoreThreadTimeOut is set - int
maximum-pool-size - the maximum number of threads to allow in the pool - int
keep-alive-time - when the number of threads is greater than the core, this is the maximum time that excess idle threads will wait for new tasks before terminating. - long
unit - the time unit for the keepAliveTime argument - java.util.concurrent.TimeUnit
work-queue - the queue to use for holding tasks before they are executed. This queue will hold only the Runnable tasks submitted by the execute method. - java.util.concurrent.BlockingQueue
thread-factory - the factory to use when the executor creates a new thread - java.util.concurrent.ThreadFactory
handler - the handler to use when execution is blocked because the thread bounds and queue capacities are reached - java.util.concurrent.RejectedExecutionHandler
throws: java.lang.IllegalArgumentException - if one of the following holds: corePoolSize < 0 keepAliveTime < 0 maximumPoolSize <= 0 maximumPoolSize < corePoolSize
Constructor. Creates a new ThreadPoolExecutor with the given initial parameters. core-pool-size - the number of threads to keep in the pool, even if they are idle, unless allowCoreThreadTimeOut is set - `int` maximum-pool-size - the maximum number of threads to allow in the pool - `int` keep-alive-time - when the number of threads is greater than the core, this is the maximum time that excess idle threads will wait for new tasks before terminating. - `long` unit - the time unit for the keepAliveTime argument - `java.util.concurrent.TimeUnit` work-queue - the queue to use for holding tasks before they are executed. This queue will hold only the Runnable tasks submitted by the execute method. - `java.util.concurrent.BlockingQueue` thread-factory - the factory to use when the executor creates a new thread - `java.util.concurrent.ThreadFactory` handler - the handler to use when execution is blocked because the thread bounds and queue capacities are reached - `java.util.concurrent.RejectedExecutionHandler` throws: java.lang.IllegalArgumentException - if one of the following holds: corePoolSize < 0 keepAliveTime < 0 maximumPoolSize <= 0 maximumPoolSize < corePoolSize
allow-core-thread-time-outclj
(allow-core-thread-time-out this value)Sets the policy governing whether core threads may time out and terminate if no tasks arrive within the keep-alive time, being replaced if needed when new tasks arrive. When false, core threads are never terminated due to lack of incoming tasks. When true, the same keep-alive policy applying to non-core threads applies also to core threads. To avoid continual thread replacement, the keep-alive time must be greater than zero when setting true. This method should in general be called before the pool is actively used.
value - true if should time out, else false - boolean
throws: java.lang.IllegalArgumentException - if value is true and the current keep-alive time is not greater than zero
Sets the policy governing whether core threads may time out and terminate if no tasks arrive within the keep-alive time, being replaced if needed when new tasks arrive. When false, core threads are never terminated due to lack of incoming tasks. When true, the same keep-alive policy applying to non-core threads applies also to core threads. To avoid continual thread replacement, the keep-alive time must be greater than zero when setting true. This method should in general be called before the pool is actively used. value - true if should time out, else false - `boolean` throws: java.lang.IllegalArgumentException - if value is true and the current keep-alive time is not greater than zero
allows-core-thread-time-outclj
(allows-core-thread-time-out this)Returns true if this pool allows core threads to time out and terminate if no tasks arrive within the keepAlive time, being replaced if needed when new tasks arrive. When true, the same keep-alive policy applying to non-core threads applies also to core threads. When false (the default), core threads are never terminated due to lack of incoming tasks.
returns: true if core threads are allowed to time out,
else false - boolean
Returns true if this pool allows core threads to time out and
terminate if no tasks arrive within the keepAlive time, being
replaced if needed when new tasks arrive. When true, the same
keep-alive policy applying to non-core threads applies also to
core threads. When false (the default), core threads are never
terminated due to lack of incoming tasks.
returns: true if core threads are allowed to time out,
else false - `boolean`await-terminationclj
(await-termination this timeout unit)Description copied from interface: ExecutorService
timeout - the maximum time to wait - long
unit - the time unit of the timeout argument - java.util.concurrent.TimeUnit
returns: true if this executor terminated and
false if the timeout elapsed before termination - boolean
throws: java.lang.InterruptedException - if interrupted while waiting
Description copied from interface: ExecutorService
timeout - the maximum time to wait - `long`
unit - the time unit of the timeout argument - `java.util.concurrent.TimeUnit`
returns: true if this executor terminated and
false if the timeout elapsed before termination - `boolean`
throws: java.lang.InterruptedException - if interrupted while waitingexecuteclj
(execute this command)Executes the given task sometime in the future. The task may execute in a new thread or in an existing pooled thread.
If the task cannot be submitted for execution, either because this executor has been shutdown or because its capacity has been reached, the task is handled by the current RejectedExecutionHandler.
command - the task to execute - java.lang.Runnable
throws: java.util.concurrent.RejectedExecutionException - at discretion of RejectedExecutionHandler, if the task cannot be accepted for execution
Executes the given task sometime in the future. The task may execute in a new thread or in an existing pooled thread. If the task cannot be submitted for execution, either because this executor has been shutdown or because its capacity has been reached, the task is handled by the current RejectedExecutionHandler. command - the task to execute - `java.lang.Runnable` throws: java.util.concurrent.RejectedExecutionException - at discretion of RejectedExecutionHandler, if the task cannot be accepted for execution
get-active-countclj
(get-active-count this)Returns the approximate number of threads that are actively executing tasks.
returns: the number of threads - int
Returns the approximate number of threads that are actively executing tasks. returns: the number of threads - `int`
get-completed-task-countclj
(get-completed-task-count this)Returns the approximate total number of tasks that have completed execution. Because the states of tasks and threads may change dynamically during computation, the returned value is only an approximation, but one that does not ever decrease across successive calls.
returns: the number of tasks - long
Returns the approximate total number of tasks that have completed execution. Because the states of tasks and threads may change dynamically during computation, the returned value is only an approximation, but one that does not ever decrease across successive calls. returns: the number of tasks - `long`
get-core-pool-sizeclj
(get-core-pool-size this)Returns the core number of threads.
returns: the core number of threads - int
Returns the core number of threads. returns: the core number of threads - `int`
get-keep-alive-timeclj
(get-keep-alive-time this unit)Returns the thread keep-alive time, which is the amount of time that threads in excess of the core pool size may remain idle before being terminated.
unit - the desired time unit of the result - java.util.concurrent.TimeUnit
returns: the time limit - long
Returns the thread keep-alive time, which is the amount of time that threads in excess of the core pool size may remain idle before being terminated. unit - the desired time unit of the result - `java.util.concurrent.TimeUnit` returns: the time limit - `long`
get-largest-pool-sizeclj
(get-largest-pool-size this)Returns the largest number of threads that have ever simultaneously been in the pool.
returns: the number of threads - int
Returns the largest number of threads that have ever simultaneously been in the pool. returns: the number of threads - `int`
get-maximum-pool-sizeclj
(get-maximum-pool-size this)Returns the maximum allowed number of threads.
returns: the maximum allowed number of threads - int
Returns the maximum allowed number of threads. returns: the maximum allowed number of threads - `int`
get-pool-sizeclj
(get-pool-size this)Returns the current number of threads in the pool.
returns: the number of threads - int
Returns the current number of threads in the pool. returns: the number of threads - `int`
get-queueclj
(get-queue this)Returns the task queue used by this executor. Access to the task queue is intended primarily for debugging and monitoring. This queue may be in active use. Retrieving the task queue does not prevent queued tasks from executing.
returns: the task queue - java.util.concurrent.BlockingQueue<java.lang.Runnable>
Returns the task queue used by this executor. Access to the task queue is intended primarily for debugging and monitoring. This queue may be in active use. Retrieving the task queue does not prevent queued tasks from executing. returns: the task queue - `java.util.concurrent.BlockingQueue<java.lang.Runnable>`
get-rejected-execution-handlerclj
(get-rejected-execution-handler this)Returns the current handler for unexecutable tasks.
returns: the current handler - java.util.concurrent.RejectedExecutionHandler
Returns the current handler for unexecutable tasks. returns: the current handler - `java.util.concurrent.RejectedExecutionHandler`
get-task-countclj
(get-task-count this)Returns the approximate total number of tasks that have ever been scheduled for execution. Because the states of tasks and threads may change dynamically during computation, the returned value is only an approximation.
returns: the number of tasks - long
Returns the approximate total number of tasks that have ever been scheduled for execution. Because the states of tasks and threads may change dynamically during computation, the returned value is only an approximation. returns: the number of tasks - `long`
get-thread-factoryclj
(get-thread-factory this)Returns the thread factory used to create new threads.
returns: the current thread factory - java.util.concurrent.ThreadFactory
Returns the thread factory used to create new threads. returns: the current thread factory - `java.util.concurrent.ThreadFactory`
prestart-all-core-threadsclj
(prestart-all-core-threads this)Starts all core threads, causing them to idly wait for work. This overrides the default policy of starting core threads only when new tasks are executed.
returns: the number of threads started - int
Starts all core threads, causing them to idly wait for work. This overrides the default policy of starting core threads only when new tasks are executed. returns: the number of threads started - `int`
prestart-core-threadclj
(prestart-core-thread this)Starts a core thread, causing it to idly wait for work. This overrides the default policy of starting core threads only when new tasks are executed. This method will return false if all core threads have already been started.
returns: true if a thread was started - boolean
Starts a core thread, causing it to idly wait for work. This overrides the default policy of starting core threads only when new tasks are executed. This method will return false if all core threads have already been started. returns: true if a thread was started - `boolean`
purgeclj
(purge this)Tries to remove from the work queue all Future tasks that have been cancelled. This method can be useful as a storage reclamation operation, that has no other impact on functionality. Cancelled tasks are never executed, but may accumulate in work queues until worker threads can actively remove them. Invoking this method instead tries to remove them now. However, this method may fail to remove tasks in the presence of interference by other threads.
Tries to remove from the work queue all Future tasks that have been cancelled. This method can be useful as a storage reclamation operation, that has no other impact on functionality. Cancelled tasks are never executed, but may accumulate in work queues until worker threads can actively remove them. Invoking this method instead tries to remove them now. However, this method may fail to remove tasks in the presence of interference by other threads.
removeclj
(remove this task)Removes this task from the executor's internal queue if it is present, thus causing it not to be run if it has not already started.
This method may be useful as one part of a cancellation scheme. It may fail to remove tasks that have been converted into other forms before being placed on the internal queue. For example, a task entered using submit might be converted into a form that maintains Future status. However, in such cases, method purge() may be used to remove those Futures that have been cancelled.
task - the task to remove - java.lang.Runnable
returns: true if the task was removed - boolean
Removes this task from the executor's internal queue if it is present, thus causing it not to be run if it has not already started. This method may be useful as one part of a cancellation scheme. It may fail to remove tasks that have been converted into other forms before being placed on the internal queue. For example, a task entered using submit might be converted into a form that maintains Future status. However, in such cases, method purge() may be used to remove those Futures that have been cancelled. task - the task to remove - `java.lang.Runnable` returns: true if the task was removed - `boolean`
set-core-pool-sizeclj
(set-core-pool-size this core-pool-size)Sets the core number of threads. This overrides any value set in the constructor. If the new value is smaller than the current value, excess existing threads will be terminated when they next become idle. If larger, new threads will, if needed, be started to execute any queued tasks.
core-pool-size - the new core size - int
throws: java.lang.IllegalArgumentException - if corePoolSize < 0
Sets the core number of threads. This overrides any value set in the constructor. If the new value is smaller than the current value, excess existing threads will be terminated when they next become idle. If larger, new threads will, if needed, be started to execute any queued tasks. core-pool-size - the new core size - `int` throws: java.lang.IllegalArgumentException - if corePoolSize < 0
set-keep-alive-timeclj
(set-keep-alive-time this time unit)Sets the time limit for which threads may remain idle before being terminated. If there are more than the core number of threads currently in the pool, after waiting this amount of time without processing a task, excess threads will be terminated. This overrides any value set in the constructor.
time - the time to wait. A time value of zero will cause excess threads to terminate immediately after executing tasks. - long
unit - the time unit of the time argument - java.util.concurrent.TimeUnit
throws: java.lang.IllegalArgumentException - if time less than zero or if time is zero and allowsCoreThreadTimeOut
Sets the time limit for which threads may remain idle before being terminated. If there are more than the core number of threads currently in the pool, after waiting this amount of time without processing a task, excess threads will be terminated. This overrides any value set in the constructor. time - the time to wait. A time value of zero will cause excess threads to terminate immediately after executing tasks. - `long` unit - the time unit of the time argument - `java.util.concurrent.TimeUnit` throws: java.lang.IllegalArgumentException - if time less than zero or if time is zero and allowsCoreThreadTimeOut
set-maximum-pool-sizeclj
(set-maximum-pool-size this maximum-pool-size)Sets the maximum allowed number of threads. This overrides any value set in the constructor. If the new value is smaller than the current value, excess existing threads will be terminated when they next become idle.
maximum-pool-size - the new maximum - int
throws: java.lang.IllegalArgumentException - if the new maximum is less than or equal to zero, or less than the core pool size
Sets the maximum allowed number of threads. This overrides any value set in the constructor. If the new value is smaller than the current value, excess existing threads will be terminated when they next become idle. maximum-pool-size - the new maximum - `int` throws: java.lang.IllegalArgumentException - if the new maximum is less than or equal to zero, or less than the core pool size
set-rejected-execution-handlerclj
(set-rejected-execution-handler this handler)Sets a new handler for unexecutable tasks.
handler - the new handler - java.util.concurrent.RejectedExecutionHandler
throws: java.lang.NullPointerException - if handler is null
Sets a new handler for unexecutable tasks. handler - the new handler - `java.util.concurrent.RejectedExecutionHandler` throws: java.lang.NullPointerException - if handler is null
set-thread-factoryclj
(set-thread-factory this thread-factory)Sets the thread factory used to create new threads.
thread-factory - the new thread factory - java.util.concurrent.ThreadFactory
throws: java.lang.NullPointerException - if threadFactory is null
Sets the thread factory used to create new threads. thread-factory - the new thread factory - `java.util.concurrent.ThreadFactory` throws: java.lang.NullPointerException - if threadFactory is null
shutdownclj
(shutdown this)Initiates an orderly shutdown in which previously submitted tasks are executed, but no new tasks will be accepted. Invocation has no additional effect if already shut down.
This method does not wait for previously submitted tasks to complete execution. Use awaitTermination to do that.
throws: java.lang.SecurityException - if a security manager exists and shutting down this ExecutorService may manipulate threads that the caller is not permitted to modify because it does not hold RuntimePermission("modifyThread"), or the security manager's checkAccess method denies access.
Initiates an orderly shutdown in which previously submitted
tasks are executed, but no new tasks will be accepted.
Invocation has no additional effect if already shut down.
This method does not wait for previously submitted tasks to
complete execution. Use awaitTermination
to do that.
throws: java.lang.SecurityException - if a security manager exists and shutting down this ExecutorService may manipulate threads that the caller is not permitted to modify because it does not hold RuntimePermission("modifyThread"), or the security manager's checkAccess method denies access.shutdown-nowclj
(shutdown-now this)Attempts to stop all actively executing tasks, halts the processing of waiting tasks, and returns a list of the tasks that were awaiting execution. These tasks are drained (removed) from the task queue upon return from this method.
This method does not wait for actively executing tasks to terminate. Use awaitTermination to do that.
There are no guarantees beyond best-effort attempts to stop processing actively executing tasks. This implementation cancels tasks via Thread.interrupt(), so any task that fails to respond to interrupts may never terminate.
returns: list of tasks that never commenced execution - java.util.List<java.lang.Runnable>
throws: java.lang.SecurityException - if a security manager exists and shutting down this ExecutorService may manipulate threads that the caller is not permitted to modify because it does not hold RuntimePermission("modifyThread"), or the security manager's checkAccess method denies access.
Attempts to stop all actively executing tasks, halts the
processing of waiting tasks, and returns a list of the tasks
that were awaiting execution. These tasks are drained (removed)
from the task queue upon return from this method.
This method does not wait for actively executing tasks to
terminate. Use awaitTermination to
do that.
There are no guarantees beyond best-effort attempts to stop
processing actively executing tasks. This implementation
cancels tasks via Thread.interrupt(), so any task that
fails to respond to interrupts may never terminate.
returns: list of tasks that never commenced execution - `java.util.List<java.lang.Runnable>`
throws: java.lang.SecurityException - if a security manager exists and shutting down this ExecutorService may manipulate threads that the caller is not permitted to modify because it does not hold RuntimePermission("modifyThread"), or the security manager's checkAccess method denies access.shutdown?clj
(shutdown? this)Description copied from interface: ExecutorService
returns: true if this executor has been shut down - boolean
Description copied from interface: ExecutorService returns: true if this executor has been shut down - `boolean`
terminated?clj
(terminated? this)Description copied from interface: ExecutorService
returns: true if all tasks have completed following shut down - boolean
Description copied from interface: ExecutorService returns: true if all tasks have completed following shut down - `boolean`
terminating?clj
(terminating? this)Returns true if this executor is in the process of terminating after shutdown() or shutdownNow() but has not completely terminated. This method may be useful for debugging. A return of true reported a sufficient period after shutdown may indicate that submitted tasks have ignored or suppressed interruption, causing this executor not to properly terminate.
returns: true if terminating but not yet terminated - boolean
Returns true if this executor is in the process of terminating after shutdown() or shutdownNow() but has not completely terminated. This method may be useful for debugging. A return of true reported a sufficient period after shutdown may indicate that submitted tasks have ignored or suppressed interruption, causing this executor not to properly terminate. returns: true if terminating but not yet terminated - `boolean`
to-stringclj
(to-string this)Returns a string identifying this pool, as well as its state, including indications of run state and estimated worker and task counts.
returns: a string identifying this pool, as well as its state - java.lang.String
Returns a string identifying this pool, as well as its state, including indications of run state and estimated worker and task counts. returns: a string identifying this pool, as well as its state - `java.lang.String`
cljdoc is a website building & hosting documentation for Clojure/Script libraries
× close