Sync Over Async (ARCH3023)

Key typescript.async.sync-over-async · Severity error · Category async

Blocking on an asynchronous operation from a synchronous context risks deadlock, starves the thread pool, and defeats the entire purpose of async.

Incorrect

import { execSync } from "child_process";

function readConfig(): string {
  // synchronous call blocks the event loop
  return execSync("cat config.json").toString();
}

Correct

import { readFile } from "fs/promises";

async function readConfig(): Promise<string> {
  return await readFile("config.json", "utf8");
}

Fix

Use the asynchronous counterpart of the blocking API and await the call instead of blocking.