Atomic Counters

This Go code demonstrates the use of the sync/atomic package and the atomic.Uint64 type to perform atomic operations on a uint64 variable. Let's go through the code with inline comments:

package main

import (
	"fmt"
	"sync"
	"sync/atomic"
)

func main() {
	// Creating an atomic.Uint64 variable named 'ops'
	var ops atomic.Uint64

	// Creating a WaitGroup to wait for all goroutines to finish
	var wg sync.WaitGroup

	// Launching 50 goroutines
	for i := 0; i < 50; i++ {
		// Incrementing the WaitGroup counter for each goroutine
		wg.Add(1)

		// Launching a goroutine
		go func() {
			// Performing 1000 atomic increments on the 'ops' variable
			for c := 0; c < 1000; c++ {
				ops.Add(1)
			}

			// Decrementing the WaitGroup counter when the goroutine completes
			wg.Done()
		}()
	}

	// Waiting for all goroutines to finish
	wg.Wait()

	// Loading the final value of 'ops' using ops.Load()
	fmt.Println("ops:", ops.Load())
}

Explanation:

1. package main: Indicates that this Go file belongs to the main executable package.

2. import (...): Imports necessary packages, including "fmt" for formatting and printing, "sync" for synchronization, and "sync/atomic" for atomic operations.

3. var ops atomic.Uint64: Creates an atomic uint64 variable named 'ops' using atomic.Uint64.

4. var wg sync.WaitGroup: Creates a sync.WaitGroup variable named 'wg' to wait for all goroutines to finish.

5. Launching 50 goroutines, each performing 1000 atomic increments on the 'ops' variable.

6. ops.Add(1): Atomically increments the value of 'ops' by 1.

7. wg.Add(1): Increments the WaitGroup counter for each goroutine.

8. wg.Done(): Decrements the WaitGroup counter when a goroutine completes.

9. wg.Wait(): Waits for all goroutines to finish.

10. ops.Load(): Loads the final value of 'ops' atomically.

11. Printing the final value of 'ops'.

In summary, this code demonstrates the use of the sync/atomic package to perform atomic operations on a uint64 variable (ops). The atomic.Uint64 type provides atomic methods for performing operations like increments without the need for locks, ensuring safe concurrent access to the variable. The final value of 'ops' represents the total number of increments performed across all goroutines.

Further Explanation

In concurrent programming, the term "atomic" refers to an operation that is executed as a single, indivisible unit, without the possibility of interruption or interference by other concurrent operations. In the context of the Go programming language and its sync/atomic package, "atomic" operations are designed to be thread-safe and avoid race conditions.

In simpler terms, when an operation is atomic, it is guaranteed to be completed without being interrupted by other parallel operations. This is particularly crucial in concurrent or multithreaded programs where multiple threads or goroutines may be accessing shared data simultaneously. Without atomicity, there is a risk of data corruption or unexpected behavior due to interference between concurrent operations.

The sync/atomic package in Go provides atomic types and functions for performing atomic operations on variables. For example, atomic.AddUint64 increments a uint64 variable in an atomic manner, ensuring that the operation is completed without interruption and without the need for explicit locks.

In the provided code example, atomic.Uint64 is used to create an atomic uint64 variable named 'ops'. The Add(1) operation on 'ops' is atomic, meaning that each increment is guaranteed to complete as a single, uninterrupted operation, even when performed concurrently by multiple goroutines. This helps prevent data corruption and ensures the accuracy of the final result when multiple goroutines are involved in incrementing the variable concurrently.