React Server side + Nodejs setInterval memory leaks

Question

In my universal react application, I'm having a react component containing setInterval in componentWillMount and clearInterval in componentWillUnmount.

Fortunately, componentWillUnmount not called on the server.

componentWillMount(){
    this.checker = setInterval(this.checkForSubscription, 2000);
}

componentWillUnmount(){
    clearInterval(this.checker);
}

I'm suffering from crashes and memory leaks on my express server. I created heapdumps and analysis those on chrome memory tool.

Unfortunately, got no success to find memory leaks. So, when I remove the setInterval from server side logic by checking typeof for window object. I do not create any crash since then. So, I want to know the code above is the cause of memory leaks and why?

Denis Rybalka · Accepted Answer · 2017-12-25 19:41:03Z

1

You can safely migrate you method to componenDidMount which is not called on server

componentDidlMount(){
    this.checker = setInterval(this.checkForSubscription, 2000);
}

componentWillUnmount(){
    clearInterval(this.checker);
}

what you can also do is using more packages like can-use-dom

import canUseDOM from 'can-use-dom';
componentWillMount(){
    canUseDOM && this.checker = setInterval(this.checkForSubscription, 2000);
}

componentWillUnmount(){
    clearInterval(this.checker);
}

If you are using webpack you can just define an env variable in config

   new webpack.DefinePlugin({
      'process.env': {
        BROWSER: JSON.stringify(true),
      },
    }),

and use condition process.env.BROWSER && "your code"

answered Dec 25, 2017 at 19:41

Denis Rybalka

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2 Comments

Anurag Jain Over a year ago

I can handle this with ease by checking the existence of the window object. My question is, will it create a memory leak on node server since componentWillUnmount is not called on the server?

Denis Rybalka Over a year ago

No, all 3 examples will not create any memory leaks

Anurag Jain · Accepted Answer · 2018-01-15 16:24:51Z

0

I found it my own. The problem with above code is that it cannot call clearInterval on the server side since componentWillUnmount has not called on the server. So, it causes a memory leak on server.

Once I set the check for the existence of window object, it only called on the client side. So, no server crash since then.

answered Jan 15, 2018 at 16:24

Anurag Jain

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