Code Review: Promise Concurrency Exhaustion

mediumCode ReviewJS / TS

Problem Statement

Review the following batch notification dispatcher. Identify why firing thousands of HTTP requests with unrestricted `Promise.all()` leads to socket exhaustion, memory spikes, and API rate limit bans. Refactor with controlled concurrency.

Code under review

JAVASCRIPT• handler.js

Pairlet Snippet

// Batch newsletter dispatcher
async function dispatchBulkNotifications(subscribers, message) {
  console.log(`Starting dispatch to ${subscribers.length} subscribers...`);

  const results = await Promise.all(
    subscribers.map(sub => 
      sendEmailViaSendgrid(sub.email, message.subject, message.body)
    )
  );

  return { dispatched: results.length };
}

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Code Review: Promise Concurrency Exhaustion

Problem Statement

Code under review

Practice solo

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