SharedArrayBuffer for shared memory in Node.js - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a SharedArrayBuffer of 1024 bytes.

Node.js

const sharedBuffer = new [1](1024);

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AUint8Array

BSharedArrayBuffer

CArrayBuffer

DBuffer

Attempts:

3 left

💡 Hint

Common Mistakes

Using ArrayBuffer instead of SharedArrayBuffer

Using Buffer which is Node.js specific but not shared memory

The SharedArrayBuffer constructor creates a buffer that can be shared between threads.

2fill in blank

medium

Complete the code to create a typed array view over the shared buffer.

Node.js

const sharedArray = new [1](sharedBuffer);

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AInt16Array

BArray

CFloat32Array

DUint8Array

Attempts:

3 left

💡 Hint

Common Mistakes

Using Array which is not a typed array

Using Float32Array which is for 4-byte floats, not bytes

Uint8Array creates a typed array view over the buffer, allowing byte-level access.

3fill in blank

hard

Fix the error in the code to safely increment a shared counter using Atomics.

Node.js

Atomics.[1](sharedArray, 0, 1);

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Aadd

Bincrement

Cstore

Dload

Attempts:

3 left

💡 Hint

Common Mistakes

Using Atomics.increment which does not exist

Using Atomics.store which replaces the value instead of adding

Atomics.add safely adds a value to the shared array at the given index.

4fill in blank

hard

Fill both blanks to create a shared buffer and a typed array view of 32-bit integers.

Node.js

const buffer = new [1](128);
const intArray = new [2](buffer);

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ASharedArrayBuffer

BArrayBuffer

CInt32Array

DUint8Array

Attempts:

3 left

💡 Hint

Common Mistakes

Using ArrayBuffer instead of SharedArrayBuffer

Using Uint8Array instead of Int32Array for 32-bit integers

Use SharedArrayBuffer to create shared memory and Int32Array to view it as 32-bit integers.

5fill in blank

hard

Fill all three blanks to atomically compare and exchange a value in the shared array.

Node.js

const oldValue = Atomics.[1](sharedArray, [2], [3], 42);

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AcompareExchange

B0

C41

Dexchange

Attempts:

3 left

💡 Hint

Common Mistakes

Using Atomics.exchange which does not compare before swapping

Using wrong index or old value parameters

Atomics.compareExchange compares the value at index 0 with 41, and if equal, replaces it with 42.