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Go – StorePointer() in sync/atomic package

In this article, we will explore the StorePointer() Function in sync/atomic package in Go in details, along with examples.

The StorePointer function in go is part of the “sync/atomic” package in Go, which provides low-level atomic memory operations. This function atomically sets the value of a pointer variable. It is a write operation that ensures the value written is immediately visible to other concurrent threads. The function signature is as follows:


func StorePointer(addr *unsafe.Pointer, val unsafe.Pointer)

The function takes a pointer to an unsafe.Pointer variable addr and an unsafe.Pointer value val as arguments. It sets the value of addr to val atomically.


To illustrate the usage of the StorePointer function, let’s create a simple program simulating concurrent data access. We will create two goroutines: one that sets a shared flag pointer to a specific address using the StorePointer function and another that reads and prints the flag value using the atomic.LoadPointer function.

package main

import (







func main() {

	var flag *int

	flags := []int{1, 2, 3, 4, 5}

	var sharedFlag unsafe.Pointer

	var wg sync.WaitGroup

	// Writer goroutine

	go func() {

		defer wg.Done()

		for _, v := range flags {

			atomic.StorePointer(&sharedFlag, unsafe.Pointer(&v))

			fmt.Printf("Writer: Flag set to %d\n", v)

			time.Sleep(time.Millisecond * 500)



	// Reader goroutine

	go func() {

		defer wg.Done()

		for i := 0; i < 10; i++ {

			flag = (*int)(atomic.LoadPointer(&sharedFlag))

			fmt.Printf("Reader: Current flag value is %d\n", *flag)

			time.Sleep(time.Millisecond * 250)





In this example, we use the sync.WaitGroup to ensure that both goroutines complete before the program exits. The writer goroutine sets the sharedFlag value using the atomic.StorePointer function, ensuring atomicity. Meanwhile, the reader goroutine reads the sharedFlag value using the atomic.LoadPointer function, guaranteeing that it always reads the latest value written by the writer goroutine.

This example demonstrates how the StorePointer function can be used to perform atomic write operations on a shared pointer variable, ensuring data consistency across concurrent threads.


The StorePointer function is a critical utility provided by the sync/atomic package in Go, enabling atomic write operations on pointer variables. It is particularly useful in concurrent programming when multiple goroutines access shared memory. Using the StorePointer function ensures data consistency and helps eliminate race conditions, contributing to the overall stability and reliability of your concurrent Go applications.

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Posted in golang, packages, sync

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