Java programming language has multithreading built in as a core feature allowing users to build applications which are very engaging. What is multithreading in computing? There are various definitions available, but to put it simply, it's the concurrent execution of two or more threads. A thread in this context is sometimes described as a lightweight process, the thread can run independently from others but it has to share resources like memory.
To enable faster execution and increased performance of current applications there is always an efficiency placed over running tasks in parallel which in turn increases CPU utilization rates.
As for the question on how to comprehend multithreading in Java, it would be right to start with threads as well as thread management as the underlying framework in their functioning.
A thread can be defined as the smallest unit of concurrency. Each thread is capable of executing its own sequence of instructions which is unique from any other thread and thus enabling them to execute tasks independently from other threads. The operating system is at the forefront of scheduling the execution of threads and has tools which allow it to facilitate switching of threads efficiently in and out of the processor.
Java employs the
Thread class to manage threads, with two typical thread creation strategies: Thread Sub-Classing and Runnable Interface. Write a subclass of the Thread class and implement the run() function to dictate the specialized action on this thread. Interfaces can be implemented in a class, such as the Runnable interface which requires coding for the run() method that will handle the purpose of the thread.Every thread has its own identification code and is registered with the operating system's scheduler. Based on the scheduling techniques, the operating system selects which thread to run whenever needed.
Various Life Cycles of a Thread
Many states are recognized during the cycles of a java thread. These states will help to understand the process of execution of the threads in different levels: New, Runnable, Blocked, Waiting, Timed Waiting, and Terminated. Such comprehension of these states is beneficial to the programmers in transfer of state so that threads do not overconsuming resources and deadlock does not occur.Thread Synchronization
Despite the fact that the use of multithreading increases performance, it increases the complexity since different threads may simultaneously access the same resources causing conflicts. This may lead to data inconsistency or resource conflicts. To prevent such problems, thread synchronization is implemented.
In Java, one thread executes a method and code having the same key features (lock) a resource Exclusively - this is the meaning of synchronization. Several synchronization methods are supported in Java: Synchronized Methods, Synchronized Blocks, and Locks such as
ReentrantLock . Multi-threaded applications must utilize appropriate synchronization to ensure consistency and prevent conflicts amongst multiple threads.Thread Communication
When dealing with multithreading, communication between threads is important for overlapping their work. Java provides the following methods for inter-thread communication: wait(), notify(), and notifyAll(). When using these methods when they are needed and as they are intended, threads are able to work together without having their work muddy the waters of other threads.Executor Framework
The Executor Framework is an Intrinsic part of the package java.util.concurrent . To manage threads, the Executor Framework is more efficient than managing threads manually. However, it is more advanced in the sense of interfacing with managing threads as in the context of GUI frameworks.The Executor Framework provides a way to submit tasks to an executor for execution. Behind the scenes, the executor takes care of thread creation and management. Executors services are evolutive and can be defined as FixedThreadPool, CachedThreadPool, and SingleThreadExecutor. The necessity of working with multiple threads is made easier due to the Executor Framework because there is very little need to manage and supervise threads at a very granular level.
Thread Safety
Thread safety, also known as concurrency control, means that a program or a data structure can work correctly regardless of how many threads access it at the same time. To be able to provide thread safety, software engineers should be able to design software applications that can allow concurrent access to a shared resource without the chances of data inconsistency/corruption.Specific approaches that could help avoid any threads corruption include Immutable Objects, Atomic Variables, and ThreadLocal Variables. Following the principles of thread-safety allows developers to build apps that are efficient during multithreading without having unexpected behavior.
Deadlock in Multithreading
A deadlock occurs when two or more threads are blocked while trying to access the same resource and waiting for each other to unlock the resources. This will make the program stuck for a long time.To prevent deadlocks from happening, it is critical to adhere to principles such as Lock Ordering, Lock Timeout, and Deadlock Detection. The appropriate management of resources and synchronization will enhance efficiency when it comes to multithreaded programs.
