Init pool only once per build execution

lib/processors/uglifier.js

@@ -1,3 +1,18 @@
+const workerpool = require("workerpool");
+let _pool;
+
+function pool({buildContext}) {
+	if (!_pool) {
+		_pool = workerpool.pool(__dirname + "/uglifier_worker.js", {
+			workerType: "auto"
+		});
+		buildContext.registerCleanupTask(() => {
+			_pool.terminate();
+			_pool = null;
+		});
+	}
+	return _pool;
+}
 
 /**
  * Minifies the supplied resources.
@@ -8,24 +23,16 @@
  * @param {module:@ui5/fs.Resource[]} parameters.resources List of resources to be processed
  * @returns {Promise<module:@ui5/fs.Resource[]>} Promise resolving with uglified resources
  */
-module.exports = function({resources}) {
-	const workerpool = require("workerpool");
-	const pool = workerpool.pool(__dirname + "/uglifier_worker.js", {
-		workerType: "auto"
-	});
-
+module.exports = function({resources, buildContext}) {
 	return Promise.all(resources.map((resource) => {
 		return resource.getString().then((code) => {
-			return pool.exec("uglify", [{
+			return pool({buildContext}).exec("uglify", [{
 				filePath: resource.getPath(),
 				code
 			}]);
 		}).then((uglifiedCode) => {
 			resource.setString(uglifiedCode);
 			return resource;
 		});
-	})).then((processedResources) => {
-		pool.terminate();
-		return processedResources;
-	});
+	}));
 };

lib/tasks/uglify.js

@@ -11,11 +11,12 @@ const uglifyProcessor = require("../processors/uglifier");
  * @param {string} parameters.options.pattern Pattern to locate the files to be processed
  * @returns {Promise<undefined>} Promise resolving with <code>undefined</code> once data has been written
  */
-module.exports = function({workspace, options}) {
+module.exports = function({workspace, options, buildContext}) {
 	return workspace.byGlobSource(options.pattern)
 		.then((allResources) => {
 			return uglifyProcessor({
-				resources: allResources
+				resources: allResources,
+				buildContext
 			});
 		})
 		.then((processedResources) => {

lib/types/application/ApplicationBuilder.js

@@ -20,7 +20,7 @@ const tasks = { // can't require index.js due to circular dependency
 };
 
 class ApplicationBuilder extends AbstractBuilder {
-	addStandardTasks({resourceCollections, project, log}) {
+	addStandardTasks({resourceCollections, project, log, buildContext}) {
 		if (!project.metadata.namespace) {
 			log.info("Skipping some tasks due to missing application namespace information. If your project contains " +
 					"a Component.js, you might be missing a manifest.json file. " +
@@ -161,6 +161,7 @@ class ApplicationBuilder extends AbstractBuilder {
 		this.addTask("uglify", () => {
 			const uglify = tasks.uglify;
 			return uglify({
+				buildContext,
 				workspace: resourceCollections.workspace,
 				options: {
 					pattern: "/**/*.js"

lib/types/library/LibraryBuilder.js

@@ -200,6 +200,7 @@ class LibraryBuilder extends AbstractBuilder {
 		this.addTask("uglify", () => {
 			const uglify = tasks.uglify;
 			return uglify({
+				buildContext,
 				workspace: resourceCollections.workspace,
 				options: {
 					pattern: "/resources/**/*.js"