fix: don't cache the intermediate locals for application

lib/application.js

@@ -11,7 +11,6 @@ const { assign } = require('utility');
 const KEYS = Symbol('Application#keys');
 const HELPER = Symbol('Application#Helper');
 const LOCALS = Symbol('Application#locals');
-const LOCALS_LIST = Symbol('Application#localsList');
 const BIND_EVENTS = Symbol('Application#bindEvents');
 const WARN_CONFUSED_CONFIG = Symbol('Application#warnConfusedConfig');
 const EGG_LOADER = Symbol.for('egg#loader');
@@ -76,18 +75,15 @@ class Application extends EggApplication {
     if (!this[LOCALS]) {
       this[LOCALS] = {};
     }
-    if (this[LOCALS_LIST] && this[LOCALS_LIST].length) {
-      assign(this[LOCALS], this[LOCALS_LIST]);
-      this[LOCALS_LIST] = null;
-    }
     return this[LOCALS];
   }
 
   set locals(val) {
-    if (!this[LOCALS_LIST]) {
-      this[LOCALS_LIST] = [];
+    if (!this[LOCALS]) {
+      this[LOCALS] = {};
     }
-    this[LOCALS_LIST].push(val);
+
+    assign(this[LOCALS], val);
   }
 
   /**

test/app/extend/application.test.js

@@ -77,6 +77,32 @@ describe('test/app/extend/application.test.js', () => {
         .get('/app_same_ref')
         .expect('true');
     });
+
+    it('should app.locals not OOM', () => {
+      return app.httpRequest()
+        .get('/app_locals_oom')
+        .expect('ok');
+    });
+  });
+
+  describe('app.locals.foo = bar', () => {
+    let app;
+    before(() => {
+      app = utils.app('apps/app-locals-getter');
+      return app.ready();
+    });
+    after(() => app.close());
+
+    it('should work', () => {
+      return app.httpRequest()
+        .get('/test')
+        .expect({
+          locals: {
+            foo: 'bar',
+            abc: '123',
+          },
+        });
+    });
   });
 
   describe('app.createAnonymousContext()', () => {

test/fixtures/apps/app-locals-getter/app/router.js

@@ -0,0 +1,11 @@
+'use strict';
+
+module.exports = app => {
+  app.get('/test', function* () {
+    this.app.locals.foo = 'bar';
+    this.locals.abc = '123';
+    this.body = {
+      locals: this.locals,
+    };
+  });
+};

test/fixtures/apps/app-locals-getter/config/config.default.js

@@ -0,0 +1 @@
+exports.keys = 'foo';

test/fixtures/apps/app-locals-getter/package.json

@@ -0,0 +1,3 @@
+{
+  "name": "app-locals-getter"
+}

test/fixtures/apps/locals/app/router.js

@@ -14,6 +14,16 @@ module.exports = app => {
     this.body = app1 === app2;
   });
 
+  app.get('/app_locals_oom', function*() {
+    for (let i = 0; i < 1000; i++) {
+      app.locals = {
+        // 10MB
+        buff: Buffer.alloc(10 * 1024 * 1024).toString()
+      };
+    }
+    this.body = 'ok';
+  });
+
   app.get('/ctx_same_ref', function*() {
     let ctx1, ctx2;
     this.locals = {