Released memory in importer as early as possible

no issue

- set bigger objects to null as soon as possible
- this will trigger the GC to free memory

core/server/data/importer/importers/data/base.js

@@ -301,7 +301,7 @@ class Base {
 
         let ops = [];
 
-        _.each(this.dataToImport, (obj) => {
+        _.each(this.dataToImport, (obj, index) => {
             ops.push(() => {
                 return models[this.modelName].add(obj, options)
                     .then((importedModel) => {
@@ -321,7 +321,8 @@ class Base {
                             email: importedModel.get('email')
                         });
 
-                        return importedModel;
+                        importedModel = null;
+                        this.dataToImport.splice(index, 1);
                     })
                     .catch((err) => {
                         return this.handleError(err, obj);
@@ -337,7 +338,11 @@ class Base {
          *
          *       Promise.map(.., {concurrency: Int}) was not really improving the end performance for me.
          */
-        return sequence(ops);
+        return sequence(ops).then((response) => {
+            this.dataToImport = null;
+            ops = null;
+            return response;
+        });
     }
 }
 

core/server/data/importer/importers/data/index.js

@@ -125,6 +125,11 @@ DataImporter = {
             return toReturn;
         }).catch(function (errors) {
             return Promise.reject(errors);
+        }).finally(() => {
+            // release memory
+            importers = {};
+            results = null;
+            importData = null;
         });
     }
 };

core/server/models/base/index.js

@@ -1001,44 +1001,7 @@ ghostBookshelf.Model = ghostBookshelf.Model.extend({
                 User: 'users',
                 Tag: 'tags'
             };
-            const reducedFields = options.reducedFields;
+            const exclude = options.exclude;
-            const exclude = {
-                Post: [
-                    'title',
-                    'mobiledoc',
-                    'html',
-                    'plaintext',
-                    'amp',
-                    'codeinjection_head',
-                    'codeinjection_foot',
-                    'meta_title',
-                    'meta_description',
-                    'custom_excerpt',
-                    'og_image',
-                    'og_title',
-                    'og_description',
-                    'twitter_image',
-                    'twitter_title',
-                    'twitter_description',
-                    'custom_template'
-                ],
-                User: [
-                    'bio',
-                    'website',
-                    'location',
-                    'facebook',
-                    'twitter',
-                    'accessibility',
-                    'meta_title',
-                    'meta_description',
-                    'tour'
-                ],
-                Tag: [
-                    'description',
-                    'meta_title',
-                    'meta_description'
-                ]
-            };
             const filter = options.filter;
             const withRelated = options.withRelated;
             const withRelatedFields = options.withRelatedFields;
@@ -1080,10 +1043,10 @@ ghostBookshelf.Model = ghostBookshelf.Model.extend({
             }
 
             // exclude fields if enabled
-            if (reducedFields) {
+            if (exclude) {
                 const toSelect = _.keys(schema.tables[tableNames[modelName]]);
 
-                _.each(exclude[modelName], (key) => {
+                _.each(exclude, (key) => {
                     if (toSelect.indexOf(key) !== -1) {
                         toSelect.splice(toSelect.indexOf(key), 1);
                     }