improve RemoveParentModulesPlugin performance

sokra · sokra · commit 4daaf6cd3308 · 2018-05-01T10:41:26.000+02:00
diff --git a/lib/optimize/RemoveParentModulesPlugin.js b/lib/optimize/RemoveParentModulesPlugin.js
@@ -29,7 +29,7 @@ class RemoveParentModulesPlugin {
 		compiler.hooks.compilation.tap("RemoveParentModulesPlugin", compilation => {
 			const handler = (chunks, chunkGroups) => {
 				const queue = new Queue();
-				const availableModulesMap = new Map();
+				const availableModulesMap = new WeakMap();
 
 				for (const chunkGroup of compilation.entrypoints.values()) {
 					// initialize available modules for chunks without parents
@@ -81,7 +81,10 @@ class RemoveParentModulesPlugin {
 						chunkGroup => availableModulesMap.get(chunkGroup)
 					);
 					if (availableModulesSets.some(s => s === undefined)) continue; // No info about this chunk group
-					const availableModules = intersect(availableModulesSets);
+					const availableModules =
+						availableModulesSets.length === 1
+							? availableModulesSets[0]
+							: intersect(availableModulesSets);
 					const numberOfModules = chunk.getNumberOfModules();
 					const toRemove = new Set();
 					if (numberOfModules < availableModules.size) {
