What is the difference between thread and ExecutorService?
The advantage of ExecutorService over haphazardly spawning threads is that it behaves predictably and avoids the overhead of thread creation, which is relatively big on the JVM (it needs to reserve memory for each thread, for example).
What is ExecutorService and thread pool?
To use thread pools, we first create a object of ExecutorService and pass a set of tasks to it. ThreadPoolExecutor class allows to set the core and maximum pool size. The runnables that are run by a particular thread are executed sequentially.
What is an ExecutorService?
ExecutorService is a JDK API that simplifies running tasks in asynchronous mode. Generally speaking, ExecutorService automatically provides a pool of threads and an API for assigning tasks to it.
Does ExecutorService create a thread?
1 Answer. Short answer is that in all cases you mentioned, threads are created only when you start executing the tasks, i.e. no threads will be created after this ExecutorService exec = Executors.
Should I shutdown ExecutorService?
An ExecutorService should be shut down once it is no longer needed to free up system resources and to allow graceful application shutdown. Because the threads in an ExecutorService may be nondaemon threads, they may prevent normal application termination.
What is Executor and ExecutorService?
Executor just executes stuff you give it. ExecutorService adds startup, shutdown, and the ability to wait for and look at the status of jobs you’ve submitted for execution on top of Executor (which it extends).
Do I need to shutdown ExecutorService?
When finished using an ExecutorService , you need to shut it down explicitly. From its javadoc: “An unused ExecutorService should be shut down to allow reclamation of its resources.” Calling shutdown initiates a gradual and orderly shutdown.
What can be submitted to ExecutorService?
Submit Runnable The Java ExecutorService submit(Runnable) method also takes a Runnable implementation, but returns a Future object. This Future object can be used to check if the Runnable has finished executing.
What happens if ExecutorService is not closed?
How do I wait for ExecutorService to finish?
When using an Executor, we can shut it down by calling the shutdown() or shutdownNow() methods. Although, it won’t wait until all threads stop executing. Waiting for existing threads to complete their execution can be achieved by using the awaitTermination() method.