Fixes #604 - using single queue for export.

src/api/export.ts

@@ -19,6 +19,7 @@ type Opts = {
 	static?: string,
 	basepath?: string,
 	timeout?: number | false,
+	concurrent?: number,
 	oninfo?: ({ message }: { message: string }) => void;
 	onfile?: ({ file, size, status }: { file: string, size: number, status: number }) => void;
 };
@@ -44,6 +45,7 @@ async function _export({
 	export_dir = '__sapper__/export',
 	basepath = '',
 	timeout = 5000,
+	concurrent = 8,
 	oninfo = noop,
 	onfile = noop
 }: Opts = {}) {
@@ -87,6 +89,7 @@ async function _export({
 
 	const seen = new Set();
 	const saved = new Set();
+	const q = yootils.queue(concurrent);
 
 	function save(url: string, status: number, type: string, body: string) {
 		const { pathname } = resolve(origin, url);
@@ -162,8 +165,6 @@ async function _export({
 				if (pathname !== '/service-worker-index.html') {
 					const cleaned = clean_html(body);
 
-					const q = yootils.queue(8);
-
 					const base_match = /<base ([\s\S]+?)>/m.exec(cleaned);
 					const base_href = base_match && get_href(base_match[1]);
 					const base = resolve(url.href, base_href);
@@ -183,8 +184,6 @@ async function _export({
 							}
 						}
 					}
-
-					await q.close();
 				}
 			}
 		}
@@ -203,6 +202,7 @@ async function _export({
 
 	return ports.wait(port)
 		.then(() => handle(root))
+		.then(() => q.close())
 		.then(() => handle(resolve(root.href, 'service-worker-index.html')))
 		.then(() => proc.kill())
 		.catch(err => {