module: avoid JSON.stringify() for cache key

By avoiding JSON.stringify() and simply joining the strings with a delimiter that does not appear in paths, we can improve cached require() performance by at least 50%. Additionally, this commit removes the last source of permanent function deoptimization (const) for _findPath(). PR-URL: #10789 Reviewed-By: James M Snell <[email protected]> Reviewed-By: Michaël Zasso <[email protected]> Reviewed-By: Michael Dawson <[email protected]> Reviewed-By: Matteo Collina <[email protected]> Reviewed-By: Benjamin Gruenbaum <[email protected]>
nodejs · Mar 11, 2017 · e32425b · e32425b
1 parent 28dc848
commit e32425b
Showing 1 changed file with 5 additions and 4 deletions.
diff --git a/lib/module.js b/lib/module.js
@@ -165,10 +165,11 @@ Module._findPath = function(request, paths, isMain) {
     return false;
   }
 
-  const cacheKey = JSON.stringify({request: request, paths: paths});
-  if (Module._pathCache[cacheKey]) {
-    return Module._pathCache[cacheKey];
-  }
+  var cacheKey = request + '\x00' +
+                (paths.length === 1 ? paths[0] : paths.join('\x00'));
+  var entry = Module._pathCache[cacheKey];
+  if (entry)
+    return entry;
 
   var exts;
   var trailingSlash = request.length > 0 &&