Goroutine vs Thread in Golang

Goroutines and threads are both used for achieving concurrency in programming languages. In Golang, goroutines are the primary mechanism for achieving concurrency, while threads are a lower-level construct that is managed by the operating system.

In this article, we will explore the differences between goroutines and threads in Golang, their benefits and limitations, and when to use each of them.

Goroutines

A goroutine is a lightweight thread managed by the Go runtime. Goroutines allow multiple tasks to be executed concurrently, making it easier to write concurrent programs. Goroutines are more efficient than threads because they use less memory and can be scheduled more quickly. They can also be started and stopped quickly, which makes them ideal for use in applications that require a large number of short-lived tasks.

To create a goroutine, we use the go keyword followed by the function that we want to run concurrently. For example −

Example

package main

import "fmt"

func main() {
   go sayHello()
   fmt.Println("Main function")
}

func sayHello() {
   fmt.Println("Hello")
}

Output

Main function

In this example, the sayHello() function is executed concurrently with the main() function, allowing both to run simultaneously.

Threads

A thread is a lightweight process that is managed by the operating system. Threads are used to achieve concurrency in most programming languages. Threads are created and managed by the operating system, which makes them slower and less efficient than goroutines.

In Golang, threads are used indirectly, through the runtime scheduler. The Go runtime scheduler manages a pool of operating system threads, which are used to execute goroutines. The Go scheduler determines when to create or destroy threads based on the workload and the number of available processors.

To create a thread in Golang, we use the sync package to create a WaitGroup and the go keyword to create a new goroutine. For example −

Example

package main

import (
   "fmt"
   "sync"
)

func main() {
   var wg sync.WaitGroup
   wg.Add(1)

   go func() {
      defer wg.Done()
      fmt.Println("Hello")
   }()

   fmt.Println("Main function")

   wg.Wait()
}

Output

Main function
Hello

In this example, we use a WaitGroup to synchronize the main goroutine and the new goroutine. The WaitGroup ensures that the new goroutine completes before the main goroutine exits.

Goroutines vs Threads

The following table summarizes the main differences between goroutines and threads in Golang −

	Goroutines	Threads
Creation	Lightweight and fast	Heavyweight and slow
Memory usage	Low	High
Scheduling	Managed by the Go runtime	Managed by the operating system
Context switching	Fast	Slow
Concurrency	Safe and easy to use	Complex and error-prone
Scalability	High	Limited by the number of available processors

As shown in the table, goroutines are faster and more efficient than threads because they use less memory and can be scheduled more quickly. Goroutines are also easier to use and safer than threads because they share memory safely by default, and they don't require locks or other synchronization mechanisms.

Threads, on the other hand, are more complex and error-prone because they require explicit synchronization mechanisms to share memory safely. Threads are also slower and less efficient than goroutines because they are managed by the operating system, which adds overhead to the scheduling and context switching.

Conclusion

In conclusion, goroutines and threads are both used for achieving concurrency in programming languages. Goroutines are the primary mechanism for achieving concurrency in Golang, while threads are a lower-level construct that is managed by the operating system.

Goroutines are faster and more efficient than threads, and they are easier to use