What is the difference between concurrency and parallelism in the context of multithreading?

Concurrent vs. Parallel Multithreading: Understanding the Difference

When discussing multithreading, it's essential to differentiate between concurrency and parallelism. While both concepts involve executing multiple tasks simultaneously, they operate in distinct ways.

Concurrency

Concurrency refers to the ability of a system to handle multiple tasks at the same time. In the context of multithreading, concurrency allows different threads to make progress independently, even if they are not executed simultaneously. This is achieved through context switching, where the processor rapidly switches between threads to give the illusion of parallel execution.

Parallelism

Parallelism, on the other hand, involves true simultaneous execution of multiple tasks. In multithreading, parallelism occurs when multiple threads actually run at the same time, making use of multiple physical CPU cores or processors. This results in a significant performance boost compared to concurrency alone.

In summary, concurrency allows for the interleaved execution of tasks, while parallelism enables true simultaneous execution. Understanding the differences between these concepts is crucial for effectively designing and implementing multithreaded applications.