fix: memory leak related to logging within server-side rendering (#520)

src/server/isomorphic.ts

@@ -10,7 +10,7 @@ import { createApp, IApp } from '@/app/app';
 import { IState } from '@/app/state';
 import { IAppConfig } from '@/app/config/IAppConfig';
 import { PersistCookieStorage } from '@vuesion/addon-vuex-persist/dist/PersistCookieStorage';
-import { Logger } from './utils/Logger';
+import { createLogger } from '@/server/utils/createLogger';
 import { initHttpService } from '@shared/services/HttpService/HttpService';
 
 export interface IServerContext {
@@ -128,11 +128,17 @@ export default (context: IServerContext) => {
           resolve(app);
         }
       } catch (e) {
+        // Only create logger when necessary and make sure to clean up resources
+        // as we're running this in a new V8 context for every request.
+        // See also https://github.com/winstonjs/winston/issues/512 and https://ssr.vuejs.org/api/#runinnewcontext.
+        const Logger = createLogger();
         Logger.warn(
           'error in prefetch for route: %s; error: %s',
           router.currentRoute.fullPath,
           JSON.stringify(e, Object.getOwnPropertyNames(e)),
         );
+        Logger.clear();
+        Logger.close();
 
         reject(e);
       }

src/server/utils/Logger.ts

@@ -1,25 +1,3 @@
-import * as winston from 'winston';
+import { createLogger } from '@/server/utils/createLogger';
 
-export const Logger: winston.Logger = winston.createLogger({
-  transports: [
-    new winston.transports.File({
-      filename: 'logs/error.log',
-      level: 'error',
-      maxFiles: 5,
-      maxsize: 10485760,
-      format: winston.format.combine(winston.format.splat(), winston.format.json()),
-    }),
-    new winston.transports.File({
-      filename: 'logs/all.log',
-      maxFiles: 5,
-      maxsize: 10485760,
-      format: winston.format.combine(winston.format.splat(), winston.format.json()),
-    }),
-    new winston.transports.Console({
-      level: 'debug',
-      handleExceptions: true,
-      format: winston.format.combine(winston.format.splat(), winston.format.colorize(), winston.format.simple()),
-    }),
-  ],
-  exitOnError: false,
-});
+export const Logger = createLogger();

src/server/utils/createLogger.ts

@@ -0,0 +1,27 @@
+import * as winston from 'winston';
+
+export const createLogger = () => {
+  return winston.createLogger({
+    transports: [
+      new winston.transports.File({
+        filename: 'logs/error.log',
+        level: 'error',
+        maxFiles: 5,
+        maxsize: 10485760,
+        format: winston.format.combine(winston.format.splat(), winston.format.json()),
+      }),
+      new winston.transports.File({
+        filename: 'logs/all.log',
+        maxFiles: 5,
+        maxsize: 10485760,
+        format: winston.format.combine(winston.format.splat(), winston.format.json()),
+      }),
+      new winston.transports.Console({
+        level: 'debug',
+        handleExceptions: true,
+        format: winston.format.combine(winston.format.splat(), winston.format.colorize(), winston.format.simple()),
+      }),
+    ],
+    exitOnError: false,
+  });
+};