I'm wondering if there is any perf benchmark on raw objects vs pointers to objects.
Most of the answers/ docs that I've found basically rephrase the guidelines from the official documentation: ... If the receiver is large, a big struct for instance, it will be much cheaper to use a pointer receiver.
My question is simply what means "large" / "big"? Is a pointer on a string overkill ? what about a struct with two strings, what about a struct 3 string fields??
I think we deal with this use case quite often so it's a fair question to ask. Some advise to don't mind the performance issue but maybe some people want to use the right notation whenever they have to chance even if the performance gain is not signifiant. After all a pointer is not that expensive (i.e. one additional keystroke).
To quote the official golang documentation
...the consideration of efficiency. If the receiver is large, a big struct for instance, it will be much cheaper to use a pointer receiver.
An example where it doesn't make sense to use a pointer is for reference types (slices, maps, and channels)
As mentioned in this thread:
The concept of a reference just means something that serves the purpose of referring you to something. It's not magical.
A pointer is a simple reference that tells you where to look.
A slice tells you where to start looking and how far.
Maps and channels also just tell you where to look, but the data they reference and the operations they support on it are more complex.The point is that all the actually data is stored indirectly and all you're holding is information on how to access it.
As a result, in many cases you don't need to add another layer of indirection, unless you want a double indirection for some reason.
As twotwotwo details in "Pointers vs. values in parameters and return values", strings, interface values, and function values are also implemented with pointers.
As a consequence, you would rarely need a to use a pointer on those objects.
It's very hard to give you exact conditions since there can be different performance goals. As a rule of thumb, by default, all objects larger than 128 bits should be passed by pointer. Possible exceptions of the rule:
you are writing latency sensitive server, so you want to minimise garbage collection pressure. In order to achieve that your Request struct has byte[8] field instead of pointer to Data struct which holds byte[8]. One allocation instead of two.
etc.