Thread pool in Java

Thread pool in Java

   June 27, 2021       Ravi Yasas

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The Thread pool

Introduction

• Executor implementations use thread pools.
• The thread pool is a collection of worker threads that are ready to serve.
• Creating new threads and manage them uses a big amount of data.
• Worker threads in the thread pool will help to reduce this overhead of creating threads.
• Tasks are submitted to the pool via an internal queue called blocking queue.
• If there are more tasks than active threads, these tasks will be inserted into a blocking queue until a thread becomes available.
• A common type of thread pool is the fixed thread pool.

Fixed thread pool

• This has a specific number of running threads.
• If a thread stops, this will replace with a new thread.
• The main advantage of the fixed thread pool is it will limit the threads of an application.
• It won't let the application exceed the limit of threads that the application handles.

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Java ExecutorService

   June 27, 2021       Ravi Yasas

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Java ExecutorService

Introduction

• If an application has few threads, it can be used threads very easily using the above methods.
• But if an application has many threads, it will be not easy to handle this.
• Executors can be used to avoid this complexity.
• The executor framework is a framework that can be used for creating, managing and executing threads.
• This provides an asynchronous feature to Java applications.

Features of Executor service

• Thread creation
• Provides thread pool and various methods to create threads.
• Thread Management
• The thread pool will manage the life cycle of threads.
• Thread Execution
• Various methods will be provided
• Thread schedulers can be used.

Executor interfaces in the Java Concurrency API

• Executor
• Provides a single method execute() to create a thread.
• (new Thread(r)).start() can be replaced with e.execute(r)
• ExecutorService
• Also provides execute() method but this accepts both Runnable and Callable objects.
• ScheduledExecutorService
• This can be used to act as the asynchronous manner in Java
• It can be used periodically and after a specific timeout.
• Runnable and Callable tasks can be executed

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