Concurrency & Memory

Rust Thread-Safe Counter (Arc & Mutex)

Safely mutate shared data across multiple OS threads in Rust using Arc (Atomic Reference Counting) and Mutex synchronization.

Rust Source Code

Editable code sample with line numbers

Rust

Expected Output

When this program is compiled and executed, the terminal outputs:

Spawning 5 concurrent threads to increment counter...
  [Thread #0 incremented value by 10]
  [Thread #1 incremented value by 10]
  [Thread #2 incremented value by 10]
  [Thread #3 incremented value by 10]
  [Thread #4 incremented value by 10]
Final Counter Result: 50

How the Code Works

Rust guarantees data-race freedom at compile time. Arc allows multiple threads to share ownership of the heap-allocated Mutex, which ensures only one thread accesses the interior value at any given time.

Time Complexity

O(NumThreads)

Space Complexity

O(1) heap allocation

Key Takeaways & Best Practices

Arc<T> provides atomically reference-counted shared ownership across threads.
Mutex<T> enforces mutual exclusion and interior mutability without unsafe code.

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