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]>

Author: mscdex

lib/module.js

@@ -165,10 +165,11 @@ Module._findPath = function(request, paths, isMain){
 returnfalse;
 }
 
-constcacheKey=JSON.stringify({request: request,paths: paths});
-if(Module._pathCache[cacheKey]){
-returnModule._pathCache[cacheKey];
-}
+varcacheKey=request+'\x00'+
+(paths.length===1 ? paths[0] : paths.join('\x00'));
+varentry=Module._pathCache[cacheKey];
+if(entry)
+returnentry;
 
 varexts;
 vartrailingSlash=request.length>0&&