hardLow-Level Design

Explain the concept of 'Event Loop Pollution' and how to avoid it.

Q: Explain the concept of 'Event Loop Pollution' and how to avoid it.

**TL;DR.** **Event-loop pollution** (a.k.a. microtask/nextTick starvation) is when an endless stream of **microtasks** — recursive process.nextTick or Promise chains — keeps the loop draining microtasks so it **never reaches I/O or timer phases**. The server appears frozen even though the CPU is busy. Fix it by yielding via setImmediate and chunking work. Microtask drain keeps refilling itself never reaches <rect

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Understand the problem

Detail the negative impacts of blocking the event loop with synchronous computation.

event-loopperformanceasynchronous

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Starvation vs a yielding version

// ❌ starves the loop: nextTick re-queues before I/O can run
function spin() { process.nextTick(spin); }

// ✅ chunked with setImmediate: lets timers + sockets run between chunks
function process(items, i = 0) {
  if (i >= items.length) return;
  doWork(items[i]);
  setImmediate(() => process(items, i + 1));
}

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