Add option, so the user can choose to call libsass synchronously. This can alleviate some pressure from the cpu and the memory when rendering large or many files.

README.md

@@ -42,6 +42,10 @@ Pass in your own callback to be called upon successful compilaton by node-sass.
 
 Pass in your own callback to be called upon a sass error from node-sass. The callback has the form `callback(err)`, where err is the error string generated by libsass. Note: this *does* prevent an actual `gulpPluginError` object from being created.
 
+#### `sync: true`
+
+If you pass `sync: true` into the options hash, sass.renderSync will be called, instead of sass.render. This should help when memory and/or cpu usage is getting very high when rendering many and/or big files.
+
 ## Source Maps
 
 gulp-sass now generates *inline* source maps if you pass `sourceComments: 'map'` as an option. Note that gulp-sass won't actually do anything when passing `sourceMap: filepath`. Enjoy your source maps!

index.js

@@ -47,10 +47,7 @@ module.exports = function (options) {
                           "/*# sourceMappingURL=data:application/json;base64," +
                           sourceMap + "*/");
       }
-
-      file.path      = ext(file.path, '.css');
-      file.contents  = new Buffer(css);
-      cb(null, file);
+      handleOutput(css, file, cb);
     };
 
     opts.error = function (err) {
@@ -67,7 +64,17 @@ module.exports = function (options) {
       return cb(new gutil.PluginError('gulp-sass', err));
     };
 
-    sass.render(opts);
+	if ( opts.sync ) {
+		try {
+			var output = sass.renderSync(opts);
+			opts.success(output, null);
+			handleOutput(output, file, cb);
+		} catch(err) {
+			opts.error(err);
+		}
+	} else {
+		sass.render(opts);
+	}
 
     if (addedLocalDirPath) opts.includePaths.pop();
 
@@ -76,6 +83,12 @@ module.exports = function (options) {
   return map(nodeSass);
 };
 
+function handleOutput(output, file, cb) {
+	file.path = ext(file.path, '.css');
+	file.contents = new Buffer(output);
+	cb(null, file);
+}
+
 function getSourcesContent (sources) {
   sourcesContent = [];
 

test/test.js

@@ -58,6 +58,26 @@ test('compile a single sass file', function (t) {
   stream.write(sassFile);
 });
 
+test('compile a single sass file synchronously', function (t) {
+  var sassFile = createVinyl('mixins.scss');
+
+  var stream = gsass({sync: true});
+  stream.on('data', function (cssFile) {
+    t.ok(cssFile, 'cssFile should exist');
+    t.ok(cssFile.path, 'cssFile.path should exist');
+    t.ok(cssFile.relative, 'cssFile.relative should exist');
+    t.ok(cssFile.contents, 'cssFile.contents should exist');
+    t.equal(cssFile.path, path.join(__dirname, 'scss', 'mixins.css'));
+    t.equal(
+      fs.readFileSync(path.join(__dirname, 'ref/mixins.css'), 'utf8'),
+      cssFile.contents.toString(),
+      'file compiles correctly to css'
+    );
+    t.end();
+  })
+  stream.write(sassFile);
+});
+
 test('compile multiple sass files', function (t) {
   var files = [
     createVinyl('inheritance.scss'),
@@ -94,6 +114,19 @@ test('emit error on sass errors', function (t) {
   stream.write(errorFile);
 });
 
+test('emit error on sass errors when using sync true', function (t) {
+  var stream = gsass({sync: true});
+  var errorFile = createVinyl('somefile.sass',
+    new Buffer('body { font \'Comic Sans\'; }'));
+  stream.on('error', function (err) {
+    t.equal(err.message,
+            'source string:1: error: property "font" must be followed by a \':\'\n'
+    );
+    t.end();
+  });
+  stream.write(errorFile);
+});
+
 test('call custom error callback when opts.onError is given', function (t) {
   var stream = gsass({ onError: function (err) {
     t.equal(err,