How to write Tp framework to write horizontally scalable programs!

I watched a video yesterday about architecture. The CTO said that as an architect, the most important thing is to design a program that can be horizontally expanded

That is to say, your program can only run on one machine at the beginning, but as the number of users increases, your program must be able to expand the machine at any time. So what kind of ideas can be used to write a program that conforms to this design for the TP framework? Woolen cloth! Seeking advice from experts

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I watched a video yesterday about architecture. The CTO said that as an architect, the most important thing is to design a program that can be horizontally expanded

That is to say, your program can only run on one machine at the beginning, but as the number of users increases, your program must be able to expand the machine at any time. So what kind of ideas can be used to write a program that conforms to this design for the TP framework? Woolen cloth! Seeking advice from experts

There is a stupid way that is simple enough

For example, the SegmengtFault official website has many modules, such as articles, questions, notes, headlines, etc., each of which is designed as an independent project and independent domain name. Do not use modules to separate them. This can be deployed separately on a single server in the early stage, and can be dismantled according to the module load in the later stage. Deployed separately, the separated ones can be further loaded and balanced to facilitate so-called horizontal expansion.

Then you can try some service-oriented architectural thinking in the early stage and split the back-end API by business, so that all clients can call each other's data and avoid copying the same functional code in various places in the project