Improve core logging performance

nwoltman · nwoltman · commit 0af3f1607f8b · 2016-11-10T12:32:53.000-05:00
Allow V8 to optimize functions by not leaking the arguments object.
This results in a performance improvement of about 20%.
diff --git a/lib/layouts.js b/lib/layouts.js
@@ -33,7 +33,7 @@ function wrapErrorsWithInspect(items) {
         if (semver.satisfies(process.version, '>=6')) {
           return util.format(item);
         } else {
-          return util.format(item) + '\n' + item.stack;           
+          return util.format(item) + '\n' + item.stack;
         }
       } };
     } else {
@@ -43,7 +43,14 @@ function wrapErrorsWithInspect(items) {
 }
 
 function formatLogData(logData) {
-  var data = Array.isArray(logData) ? logData : Array.prototype.slice.call(arguments);
+  var data = logData;
+  if (!Array.isArray(data)) {
+    var numArgs = arguments.length;
+    data = new Array(numArgs);
+    for (var i = 0; i < numArgs; i++) {
+      data[i] = arguments[i];
+    }
+  }
   return util.format.apply(util, wrapErrorsWithInspect(data));
 }
 
diff --git a/lib/logger.js b/lib/logger.js
@@ -82,7 +82,10 @@ function addLevelMethods(level) {
   Logger.prototype[levelMethod] = function () {
     if (logWritesEnabled && this.isLevelEnabled(level)) {
       var numArgs = arguments.length;
-      var args = Array.prototype.slice.call(arguments);
+      var args = new Array(numArgs);
+      for (var i = 0; i < numArgs; i++) {
+        args[i] = arguments[i];
+      }
       this._log(level, args);
     }
   };
