[DropkickM16]

I think your first point is obvious, but I disagree with your second, at least 'at-scale'.

In the case where you have loose coupling but are representing multiple entities that scale in different ways, microservices allow you to separate concerns and separately scale those concerns relative to their requirements in terms of memory/CPU/disk/network/etc. The best factored code running in a single horizontally-scaled layer will be inefficient if 90% of requests are manipulating entity A, and entities B, C, and D have a lot of intricate business logic but are rarely touched (they are better off if separated and scaled individually)

The overhead you allude to is definitely something to take into account. If you're a 5-20 person startup without a serious need to scale up or lacking people who have built the tools that make microservices easy, you should avoid the issue for now. But ultimately, decoupling services so they can horizontally scale independently is a huge win.

[crdoconnor]

True, but if you prematurely divide your services up based upon what you think their performance requirements might be you will be wrong. That's premature optimization, which is, as we all know, the root of all evil.

If you've loosely coupled your services until the point where it becomes obvious that two parts of the code have markedly different performance requirements and then you decide to split them into two separate services then yes, that could work, provided you understand the trade off you're making.

I don't think that's typically what people mean by 'microservices' however.

There's a good chance it'll still be wasted effort, too. Hardware is cheap. Developers are not. That applies to large businesses and small.

[mfjordvald]

I always saw the point of micro services as not having to figure out the scaling part yet.

If you focus on grouping by purpose rather than what resource they might use then you can keep them on small instances until you better understand what kind of resource they require.

Once you learn their usage pattern you can adapt more quickly (if scale is needed at all) and not have to first split up the code.