Go: String & Conversion Optimization

Illustration created for “A Journey With Go”, made from the original Go Gopher, created by Renee French.

ℹ️ This article is based on Go 1.14.

In Go, converting an array of bytes to a string could involve a memory allocation along with a copy of the converted string. However, converting bytes to a string just to satisfy a code constraint, such as a comparison in a switch statement or as a key in a map, is definitely a waste of CPU time. Let’s review some cases and the optimizations done.

Conversion

The conversion from an array of bytes to a string involves:

• An allocation for the new string on the heap if the variable outlives the current stack frame.
• A copy of the bytes to the string.

For more details about the escape analysis, I suggest reading my article “Go: Introduction to the Escape Analysis.”

Here is a simple program that goes through those two steps:

Here is a diagram of that conversion: