Number of goroutines
- Go course
- Intermediate
- Lesson 5/80
- 4 min
Learn to launch many goroutines and concurrency.
Many goroutines
Starting many goroutines in Go is easy: write go f(i) in a loop. Each runs independently and the scheduler spreads them across cores.
Hundreds of thousands of goroutines can live at once; the memory cost is in kilobytes. This is the key trait that separates goroutines from OS threads.
But if goroutines access shared data a data race occurs. You must protect it with sync.Mutex or a channel. go test -race detects races.
Goroutine cost
A goroutine starts with about 2 KB of stack. When it fills Go doubles it automatically (growing stack). This avoids memory issues even with deep recursion.
Comparison: a Linux thread reserves 8 MB of stack. 100k threads need 800 GB; 100k goroutines run with about 200 MB.
This efficiency makes Go a top choice for concurrent server programs.
Practice Launch many goroutines
Inside main, add a go work() call inside a loop and print many started with fmt.Println.
Starter code
package main
import "fmt"
func main() {
// buraya yaz
}Sample solution
package main
import "fmt"
func work() {
fmt.Println("çoklu başladı")
}
func main() {
for i := 0; i < 3; i++ {
go work()
}
fmt.Println("çoklu başladı")
}Expected output
çoklu başladı
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 How is a data race detected?
- go run -v
- go vet
- go build -race
- go test -race Correct answer
Explanation: go vet does static analysis, not race detection.
2 Goroutine stack size
A goroutine starts with about ____ of stack.A goroutine starts with about 2 KB of stack.Explanation: 8 MB is for OS threads.
3 Match cost concepts
| Term | Meaning |
|---|---|
goroutine |
2 KB |
OS thread |
8 MB |
growing stack |
Auto-grows |
data race |
Race |