Thread Synchronization in Java

Multithreading in Java

• Multithreading enables multiple tasks in a program to be executed concurrently, making a program more responsive and interactive.
• Multithreading in Java is supported through built-in language features, allowing for the creation and execution of multiple tasks within a program.

Thread Concepts

• A thread is the flow of execution of a task, providing a mechanism for running a task.
• Multiple threads can run concurrently, sharing a single CPU through time sharing, and the operating system is responsible for scheduling and allocating resources.
• Java provides exceptionally good support for creating and running threads, as well as locking resources to prevent conflicts.

Thread Pools

• A thread pool is a group of threads that can be reused to execute multiple tasks, improving efficiency.
• The newFixedThreadPool(int) method creates a fixed number of threads in a pool, while newCachedThreadPool() creates a new thread if all threads in the pool are not idle and there are tasks waiting for execution.
• A cached pool is efficient for many short tasks, and a thread in a cached pool will be terminated if it has not been used for 60 seconds.

Thread Synchronization

• Thread synchronization is necessary to coordinate the execution of dependent threads and prevent data corruption when accessing shared resources.
• In Java, the synchronized keyword can be used to make a method thread-safe, allowing only one thread to access the method at a time.
• An example of thread synchronization is making an Account class thread-safe by adding the synchronized keyword to the deposit method.

Executor Framework

• An Executor is used to manage thread execution, and an ExecutorService provides a way to shut down the executor.
• The shutdown() method tells the executor to shut down, allowing existing tasks to finish but not accepting new tasks.