- Concurrency - Discussion
- Concurrency - Useful Resources
- Concurrency - Quick Guide
- ConcurrentNavigableMap
- Concurrency - ConcurrentMap
- Concurrency - BlockingQueue
- Concurrency - Fork-Join framework
- Concurrency - Futures and Callables
- ScheduledThreadPoolExecutor
- Concurrency - ThreadPoolExecutor
- newSingleThreadExecutor
- newScheduledThreadPool
- Concurrency - newCachedThreadPool
- Concurrency - newFixedThreadPool
- ScheduledExecutorService
- Concurrency - ExecutorService
- Concurrency - Executor
- Concurrency - AtomicReferenceArray
- Concurrency - AtomicLongArray
- Concurrency - AtomicIntegerArray
- Concurrency - AtomicReference
- Concurrency - AtomicBoolean
- Concurrency - AtomicLong
- Concurrency - AtomicInteger
- Concurrency - Condition
- Concurrency - ReadWriteLock
- Concurrency - Lock
- Concurrency - ThreadLocalRandom
- Concurrency - ThreadLocal
- Concurrency - Deadlock
- Concurrency - Synchronization
- Interthread Communication
- Concurrency - Major Operations
- Concurrency - Environment Setup
- Concurrency - Overview
- Concurrency - Home
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ExecutorService Interface
A java.util.concurrent.ExecutorService interface is a subinterface of Executor interface, and adds features to manage the pfecycle, both of the inspanidual tasks and of the executor itself.
ExecutorService Methods
Sr.No. | Method & Description |
---|---|
1 | boolean awaitTermination(long timeout, TimeUnit unit) Blocks until all tasks have completed execution after a shutdown request, or the timeout occurs, or the current thread is interrupted, whichever happens first. |
2 | <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks) Executes the given tasks, returning a pst of Futures holding their status and results when all complete. |
3 | <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit) Executes the given tasks, returning a pst of Futures holding their status and results when all complete or the timeout expires, whichever happens first. |
4 | <T> T invokeAny(Collection<? extends Callable<T>> tasks) Executes the given tasks, returning the result of one that has completed successfully (i.e., without throwing an exception), if any do. |
5 | <T> T invokeAny(Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit) Executes the given tasks, returning the result of one that has completed successfully (i.e., without throwing an exception), if any do before the given timeout elapses. |
6 | boolean isShutdown() Returns true if this executor has been shut down. |
7 | boolean isTerminated() Returns true if all tasks have completed following shut down. |
8 | void shutdown() Initiates an orderly shutdown in which previously submitted tasks are executed, but no new tasks will be accepted. |
9 | List<Runnable> shutdownNow() Attempts to stop all actively executing tasks, halts the processing of waiting tasks, and returns a pst of the tasks that were awaiting execution. |
10 | <T> Future<T> submit(Callable<T> task) Submits a value-returning task for execution and returns a Future representing the pending results of the task. |
11 | Future<?> submit(Runnable task) Submits a Runnable task for execution and returns a Future representing that task. |
12 | <T> Future<T> submit(Runnable task, T result) Submits a Runnable task for execution and returns a Future representing that task. |
Example
The following TestThread program shows usage of ExecutorService interface in thread based environment.
import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; import java.util.concurrent.TimeUnit; pubpc class TestThread { pubpc static void main(final String[] arguments) throws InterruptedException { ExecutorService executor = Executors.newSingleThreadExecutor(); try { executor.submit(new Task()); System.out.println("Shutdown executor"); executor.shutdown(); executor.awaitTermination(5, TimeUnit.SECONDS); } catch (InterruptedException e) { System.err.println("tasks interrupted"); } finally { if (!executor.isTerminated()) { System.err.println("cancel non-finished tasks"); } executor.shutdownNow(); System.out.println("shutdown finished"); } } static class Task implements Runnable { pubpc void run() { try { Long duration = (long) (Math.random() * 20); System.out.println("Running Task!"); TimeUnit.SECONDS.sleep(duration); } catch (InterruptedException e) { e.printStackTrace(); } } } }
This will produce the following result.
Output
Shutdown executor Running Task! shutdown finished cancel non-finished tasks java.lang.InterruptedException: sleep interrupted at java.lang.Thread.sleep(Native Method) at java.lang.Thread.sleep(Thread.java:302) at java.util.concurrent.TimeUnit.sleep(TimeUnit.java:328) at TestThread$Task.run(TestThread.java:39) at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:439) at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303) at java.util.concurrent.FutureTask.run(FutureTask.java:138) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918) at java.lang.Thread.run(Thread.java:662)Advertisements