Add generate.concurrency option

lib/builder/generator.js

@@ -68,7 +68,7 @@ export default class Generator extends Tapable {
     // Start generate process
     while (routes.length) {
       let n = 0
-      await Promise.all(routes.splice(0, 500).map(async ({ route, payload }) => {
+      await Promise.all(routes.splice(0, this.options.generate.concurrency).map(async ({ route, payload }) => {
         await waitFor(n++ * this.options.generate.interval)
         await this.generateRoute({route, payload, errors})
       }))

lib/core/options.js

@@ -74,6 +74,7 @@ export const defaultOptions = {
   generate: {
     dir: 'dist',
     routes: [],
+    concurrency: 500,
     interval: 0,
     minify: {
       collapseBooleanAttributes: true,