useSession's useEffect incompatible with React's strict mode

[christoph-pflueger]

Environment

System: OS: Linux 5.10 Ubuntu 20.04.4 LTS (Focal Fossa) CPU: (12) x64 Intel(R) Core(TM) i7-5930K CPU @ 3.50GHz Memory: 9.57 GB / 15.58 GB Container: Yes Shell: 5.0.17 - /bin/bash Binaries: Node: 16.15.1 - ~/.nvm/versions/node/v16.15.1/bin/node Yarn: 1.22.15 - ~/.nvm/versions/node/v16.15.1/bin/yarn npm: 8.11.0 - ~/.nvm/versions/node/v16.15.1/bin/npm npmPackages: next: 12.1.6 => 12.1.6 next-auth: ^4.6.1 => 4.6.1 react: 18.2.0 => 18.2.0

Reproduction URL

n/a

Describe the issue

As everybody knows, in React's strict mode, useEffects are run twice in development to reveal side effects. This causes useSession's useEffect to execute two requests instead of one.

How to reproduce

Should be self-explanatory.

Expected behavior

It should only perform one request, even in development using React's strict mode.

[balazsorban44]

This causes useSession's useEffect to execute two requests instead of one.

Can you describe the issue this is causing you?

[christoph-pflueger]

This causes useSession's useEffect to execute two requests instead of one.

Can you describe the issue this is causing you?

I noticed it as I was debugging another issue and wasted some time until I realized that I didn't cause two requests. So nothing major at the moment.

But the reason useEffect runs twice since React 18 is to prepare for future features, that may depend on useEffect only running once. It could be ignored for now, but a simple flag w/ useRef doesn't sound like much of an effort - unless I'm missing something.

[balazsorban44]

Yeah, I guess we could do something like https://beta.reactjs.org/learn/synchronizing-with-effects#fetching-data

But this is more of an optimization than a bug, especially since the production build won't have this behavior.

Feel free to open a PR.

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