Added thread-loader config for application code entrypoint (facebook#4582)

Author: Dmitriy Sadkovoy

packages/react-scripts/config/webpack.config.dev.js

@@ -222,7 +222,12 @@ module.exports = {
  use: [
  // This loader parallelizes code compilation, it is optional but
  // improves compile time on larger projects
- require.resolve('thread-loader'),
+ {
+ loader: require.resolve('thread-loader'),
+ options: {
+ poolTimeout: Infinity // keep workers alive for more effective watch mode
+ },
+ },
  {
  loader: require.resolve('babel-loader'),
  options: {