# std::atomic_ref<T>::is_lock_free

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< cpp‎ | atomic‎ | atomic ref

bool is_lock_free() const noexcept; |  | (since C++20)

Checks whether the atomic operations on this object are lock-free.

### Parameters

(none)

### Return value

true if the atomic operations on this object are lock-free, false otherwise.

### Notes

All atomic types except for std::atomic_flag may be implemented using mutexes or other locking operations, rather than using the lock-free atomic CPU instructions. Atomic types are also allowed to be sometimes lock-free, e.g. if only aligned memory accesses are naturally atomic on a given architecture, misaligned objects of the same type have to use locks.

The C++ standard recommends (but does not require) that lock-free atomic operations are also address-free, that is, suitable for communication between processes using shared memory.

### Example

| This section is incomplete Reason: no example

### See also

is_always_lock_free [static] | indicates that the type is always lock-free (public static member constant)

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