// Shared buffer and typed array const sab = new SharedArrayBuffer(4); const counter = new Int32Array(sab); counter[0] = 0; // Increment function function increment() { // Which line correctly increments?

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Node.js - Worker Threads

You want to safely increment a shared counter in a Node.js worker thread using SharedArrayBuffer. Which code snippet correctly increments the counter without race conditions?

// Shared buffer and typed array
const sab = new SharedArrayBuffer(4);
const counter = new Int32Array(sab);
counter[0] = 0;

// Increment function
function increment() {
  // Which line correctly increments?
}

AAtomics.add(counter, 0, 1);

Bcounter[0] = counter[0] + 1;

Ccounter[0] += 1;

Dcounter[0]++;

Step-by-Step Solution

Solution:

Step 1: Understand race conditions in shared memory
Directly modifying counter[0] with normal operators can cause race conditions when multiple threads run concurrently.
Step 2: Use atomic operations for safe increments
Atomics.add(counter, 0, 1) safely increments the value at index 0 without conflicts.
Final Answer:
Atomics.add(counter, 0, 1); -> Option A
Quick Check:
Use Atomics for safe shared memory updates [OK]

Quick Trick: Always use Atomics methods to update shared memory safely [OK]

Common Mistakes:

Using normal arithmetic on shared memory
Ignoring atomicity causing race conditions
Assuming ++ or += are thread-safe

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// Shared buffer and typed array const sab = new SharedArrayBuffer(4); const counter = new Int32Array(sab); counter[0] = 0; // Increment function function increment() { // Which line correctly increments?

Step 1: Understand race conditions in shared memory

Step 2: Use atomic operations for safe increments

Final Answer:

Quick Check:

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