How to create a cluster of multiple Raspberry Pis?

Question

Debian

So, good people, I googled on this topic, but I didn’t understand this:
Is it possible to combine several single-board computers into a cluster with power pooling to complete the task?
That is, one system on the first board takes the resources of another board or sends a task to it, part of the task, in short, create a single system based on 4 computers with automatic distribution of resources among the boards to complete the task.
Well, or how does this cluster work in general, I can’t understand the principle, parallel computing or in one thread?
Throw on the topic links to articles, manuals, videos.
I want to build a stand

Answer 1

Can be distributed. This is the task of the application.

Answer 2

Assembling a cluster from a Raspberry Pi only makes sense for fun. For performance, it is more advisable to take a Xeon of some kind not of the newest generation.
How to process data in a cluster depends very much on the application, and there is no general effective solution that will allow you to make a virtual machine with at least 5x performance compared to a single system with a dozen Raspberry Pis.
The principle is the same as you described: something takes data from somewhere, processes it, and sends the result somewhere. It is impossible to say more precisely from such a general question. For example, mining using a pool is one example of how a bunch of computers can work on a common task.
Professional data centers have fast networks, direct memory access and a bunch of other tricks that are not even approximately available on the Raspberry Pi. I think that for training it would make more sense to raise virtual machines on the desktop and set up interaction between them over a virtual network.

Answer 3

Perhaps the most effective method in this case would be to launch separate instances on each piece of hardware that will process data from one network storage (database)