Memory leak in app created from this boilerplate

[dongrh214]

Bug report

We have some problem on our server. After some time of execution we have an out of memory error on our server.
So I tried to reproduce on my computer. I create a clean project just use nextjs-starter. and build it.run it using pm2, after one three to see if the memory increase.
Here is the memory evolution :

pm2 monit show like this:

Describe the bug

you can see the heap size awaly increasing when i use loadtest request

To Reproduce

1. git clone https://github.com/iaincollins/nextjs-starter

2. cd nextjs-starter

3. npm i

4. add pm2.config.js file

     const pkg = require("./package.json");
   
     module.exports = {
          apps: [
              {
                   name: pkg.name,
                   script: "index.js",
                   instances: 1,
                   exec_mode: "cluster",
                   watch: false,
                   node_args: "--inspect --expose-gc",
                   max_memory_restart: "1500M",
                   env: {
                        NODE_ENV: "development",
                        BUILD_ENV: "test",
                        RUNTIME_ENV: "test",
                   },
                   env_test: {
                        NODE_ENV: "production",
                        BUILD_ENV: "test",
                        RUNTIME_ENV: "test",
                  },
             },
         ],
   };
   

5. npm run build

6. pm2 start pm2.config.js

7. loadtest -c 30 --rps 20 http://localhost:80

8. you can use pm2 monit or chrome://inspect See error
   I also use express test, it is ok!

system information

 OS: macOS
 Version of pm2: 4.2.1
 Version of loadtest: 4.1.0

Additional context

  use pm2 log see node inspect port