Http Client Lifetime (ARCH3083)

Key typescript.performance.http-client-lifetime · Severity error · Category performance

Creating a new HTTP client/agent for every request defeats connection pooling and piles up sockets in TIME_WAIT, causing socket exhaustion. The client should be a shared singleton.

Incorrect

async function fetchUser(id: string): Promise<User> {
  const agent = new https.Agent({ keepAlive: true });
  const res = await fetch(`/users/${id}`, { agent });
  return res.json();
}

Correct

const sharedAgent = new https.Agent({ keepAlive: true });

async function fetchUser(id: string): Promise<User> {
  const res = await fetch(`/users/${id}`, { agent: sharedAgent });
  return res.json();
}

Fix

Create the HTTP client/agent once and reuse it as a shared singleton.