Threading - In a language independent context
Tags: concurrency, parallelism, multithreading, tutorial
Published: 2023-12-30 17:48:07

Threading is a programming concept that allows multiple threads of execution to run concurrently within a single process. A thread is the smallest unit of execution within a process, and threading enables a program to perform multiple tasks simultaneously, improving efficiency and responsiveness. Threads share the same memory space and resources, such as file handles, but they have their own registers and stack, allowing them to execute independently. 

Threads, in a language-independent context, refer to the smallest unit of execution within a process. Regardless of the programming language used, threads share common principles and characteristics

### Concurrency

Threads enable concurrent execution of tasks within a single process. Multiple threads can execute independently, allowing for parallel progress on different parts of a program.

**Sequential flow**

![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/mzbvvcjgd4vhk6j9h98z.png)

**Concurrent flow**


![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/n5otwtjmjecci282vlw5.png)

### Memory Sharing

Threads within the same process share the same memory space. This shared memory allows them to access the same data and variables, simplifying communication but also necessitating synchronisation to avoid conflicts.


![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/idng1clazhg6mupueyte.png)

### Independence:

Each thread has its own program counter, register set, and stack. This independence allows threads to execute different parts of a program simultaneously.


![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/ax6mx7478ke1pn4skeyu.png)

### Thread Lifecycle:

Threads typically go through states such as creation, ready, running, blocked, and termination. The operating system's scheduler manages the transition between these states.


![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/t51r6n7ylwd650lhvbl0.png)


### Synchronisation:

Thread synchronisation is a critical aspect of multithreading, where multiple threads run concurrently in a program. Without proper synchronisation mechanisms, race conditions and other concurrency issues can arise, leading to unpredictable behaviour and data corruption. 


![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/6ya2k3xag539xf21kxun.png)

Here are some common thread synchronisation mechanisms:

> Mutex (Mutual Exclusion), Semaphore, Condition Variable, Barrier, Read-Write Locks, Atomic Operations, Thread-local Storage, Futures and Promises

You can find more details about the thread synchonisation [here](https://dev.to/binoy123/thread-synchronisation-cfb)

### Thread Safety:

Code is considered thread-safe if it can be executed by multiple threads concurrently without causing data inconsistencies or unexpected behaviour. Achieving thread safety often involves using synchronisation primitives and careful programming.


![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/w2y992you3qz4x157upx.png)


Here are some common thread safety issues:

> Race Conditions, Data Races, Deadlocks, Atomicity Violations, Inconsistent State, Non-Thread-Safe Libraries, Unprotected Access to Shared Resources, Ordering Issues

### Benefits:

Threading offers improved performance by allowing parallel execution of tasks, enhancing responsiveness in applications such as user interfaces, and optimising resource utilisation by overlapping computation and I/O operations.


![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/xu7pqf4go7w9pd88dwyb.png)

### Challenges:

Threaded programming introduces challenges such as race conditions, where multiple threads access shared data concurrently, potentially leading to unpredictable behaviour. Debugging and identifying thread-related issues can also be complex.

### Operating System Support:

Threading is typically supported by the operating system, which provides the necessary infrastructure for creating, scheduling, and managing threads.

### Purpose:

Threads are commonly used for parallelising tasks, achieving concurrency, and making efficient use of multi-core processors. They are crucial in scenarios where simultaneous execution of multiple operations is beneficial, such as in server applications, real-time systems, and multimedia processing.