Atomics.isLockFree()

The Atomics.isLockFree() static method is used to determine whether the Atomics methods use locks or atomic hardware operations when applied to typed arrays with the given element byte size. It is intended as an optimization primitive, so that high-performance algorithms can determine whether to use locks or atomic operations in critical sections. If an atomic primitive is not lock-free, it is often more efficient for an algorithm to provide its own locking.

Try it

console.log(Atomics.isLockFree(3));
// 3 is not one of the BYTES_PER_ELEMENT values
// Expected output: false

console.log(Atomics.isLockFree(4));
// 4 is one of the BYTES_PER_ELEMENT values
// Expected output: true

Syntax

Atomics.isLockFree(size)

Parameters

size

The size in bytes to check.

Return value

A true or false value indicating whether the operation is lock free.

• Always true if size is 4, because all known platforms support 4-byte atomic operations.
• Always false if the given size is not one of the BYTES_PER_ELEMENT property of integer TypedArray types.

Examples

Using Atomics.isLockFree()

Atomics.isLockFree(1); // true (platform-dependent)
Atomics.isLockFree(2); // true (platform-dependent)
Atomics.isLockFree(3); // false
Atomics.isLockFree(4); // true
Atomics.isLockFree(5); // false
Atomics.isLockFree(6); // false
Atomics.isLockFree(7); // false
Atomics.isLockFree(8); // true (platform-dependent)

Specifications

• ECMAScript® 2027 Language Specification

See also

• Atomics