A "Hello, Go!" program is deceptively simple. Let’s dissect what actually happens in memory when you run it. Spoiler: Go’s design philosophy—simplicity with precision—shines here.

The Program 

package main  

import "fmt"  

func main() {  
    msg := "Hello, Go!"  
    fmt.Println(msg)  
}

Memory Segments: A Visual Guide

Here’s how Go and your OS organize memory during execution:

+-------------------+   Lowest Address  
|      Code         |  
|-------------------|  
| main()            |  // Your compiled function  
| fmt.Println       |  // Machine code for printing  
| runtime setup     |  // Goroutines, GC initialization  
+-------------------+  
|      Data         |  
|-------------------|  
| "Hello, Go!"      |  // Immutable string (stored here at compile time)  
+-------------------+  
|      Stack        |  ↓ Grows downward  
|-------------------|  
| main() frame      |  
|   msg (pointer) → |  // Points to the Data segment  
+-------------------+  
|      Heap         |  ↑ Grows upward  
|-------------------|  
| (Temporary data)  |  // fmt.Println may use this for buffers  
+-------------------+   Highest Address

Breakdown of the Segments

1. Code Segment

  • What’s there: Compiled instructions for main(), fmt.Println, and Go’s runtime (e.g., garbage collector).
  • Why it matters: Read-only, shared across all goroutines. No redundancy.

2. Data Segment

  • What’s there: The string "Hello, Go!" (immutable). Global variables live here too.
  • Key Go behavior: Strings are read-only. Reusing msg elsewhere? It points to the same data.

3. Stack

  • What’s there: The msg variable (a pointer to the data segment) and main()’s execution context.
  • Why it’s fast: Stack allocations are just pointer adjustments. No garbage collection needed.

4. Heap

  • What’s there: Temporary buffers (e.g., fmt.Println’s internal work).
  • The nuance: In this example, the heap isn’t directly used by your code, but Go’s runtime might dip into it.

Why This Simplicity Is Revolutionary

  • No manual memory management: Unlike C/C++, you don’t malloc or free.
  • No hidden JVM/CLR: Unlike Java/C#, Go binaries are self-contained. The runtime is embedded, not a separate process.
  • Performance by default: Stacks for speed, heaps for flexibility, and a GC that stays out of your way.

The Deep Implications

  1. Strings are cheap: Since they’re immutable and stored in the data segment, copying a string only copies its pointer.
  2. Function calls are lightweight: Stacks grow/shrink dynamically per goroutine. No "stack overflow" fears (unless you’re doing recursion gone wild).
  3. The heap isn’t your enemy: Go’s GC is optimized for low latency. Most small programs (like this one) won’t notice it.

What This Teaches New Gophers

  • Trust the compiler: Go makes smart decisions about where to store data.
  • Start simple, scale later: This program’s memory footprint is microscopic, but the same principles apply to billion-request systems.

Fun Fact: The entire Go runtime (including GC) adds ~2MB to your binary. That’s why a "Hello, Go!" executable is ~2MB.