The atomic package is a set of functions for performing atomic operations provided in the Go standard library sync/atomic. Its core role is to implement concurrent and safe read and write variables without using locks. It supports int32, int64, uint32, uint64, uintptr and some pointer types. Common functions include 1.AddXxx() (atomic addition), 2.LoadXxx() (atomic reading), 3.StoreXxx() (atomic setting), 4.SwapXxx() (atomic exchange), 5.CompareAndSwapXxx() (compare and exchange), and is suitable for counters, status flags, singleton initialization and other scenarios. Note when using: 1. It cannot replace the lock to handle complex structures; 2. Poor code readability; 3. CAS may perform worse under high competition; 4. Avoid abuse; 5.32-bit platform has alignment restrictions on 64-bit variables. Mastering atomic can improve concurrency efficiency, but the synchronization mechanism should be selected reasonably based on the scenario.
In Go development, atomic
package is a very practical but overlooked tool. It is mainly used to implement lightweight concurrent synchronization operations, especially to complete atomic reading and writing of variables without using locks (i.e. sync.Mutex
).

What is atomic package?
Go's atomic
package is located in sync/atomic
in the standard library, and its main function is to provide a set of functions for performing atomic operations. The so-called "atom" means that an operation will not be interrupted once it starts. This is very important for concurrent programming, especially when multiple goroutines access shared resources at the same time.
Common scenarios include: counters, status flags, singleton initialization, etc.

What types support atomic operations?
Not all data types can be processed with atomic
package. Currently, it mainly supports the following basic types:
-
int32
-
int64
-
uint32
-
uint64
-
uintptr
- And some common pointers and structure pointers
For example, if you want to safely increment an integer counter without locking it, you can write this:

var counter int32 go func() { for i := 0; i < 1000; i { atomic.AddInt32(&counter, 1) } }()
Note: If you try to operate on the int
type, you may encounter platform difference issues, as int
may be 32 or 64 bits on different systems. It is recommended to use int32
or int64
explicitly.
What are the common atomic functions?
Here are a few of the most commonly used functions, understanding them can help you better control concurrent behavior:
-
AddXxx()
: used to do atomic addition to variables -
LoadXxx()
: used to read variable values ??atomically -
StoreXxx()
: Used to set variable values ??atomically -
SwapXxx()
: swap and return the old value -
CompareAndSwapXxx()
: Compare and exchange, often used for optimistic locking mechanism
For example, suppose you want to make sure that an initialization action is performed only once:
var initialized int32 func initOnce() { if atomic.CompareAndSwapInt32(&initialized, 0, 1) { // Execute initialization logic} }
This is lighter than using sync.Once
, but it is also harder to use correctly.
What should I pay attention to when using atomic?
Although atomic
is powerful, it is not omnipotent. Pay special attention to the following points:
- Can't replace locks : For complex data structures or operations on multiple fields, mutex locks should still be used.
- Poor readability : Compared to locking mechanisms, atomic operations are more prone to errors and are more difficult to understand and maintain.
- Performance may not necessarily be better : In highly competitive scenarios, CAS (Compare and Swap) may perform worse than Mutex.
- Don't abuse : Don't use atomic for the sake of showing off your skills unless you really need to avoid the overhead of locks.
In addition, some operations cannot atomically process 64-bit variables (such as int64
) on 32-bit platforms, so be careful about alignment issues on these platforms.
Basically that's it. Mastering atomic
can allow you to write more efficient concurrent programs, but don't forget that it is just a gadget for concurrency control, not a silver bullet that solves all problems.
The above is the detailed content of Go atomic package usage. For more information, please follow other related articles on the PHP Chinese website!

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