Why are goroutines more lightweight than OS threads in Go?

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Why are goroutines more lightweight than OS threads in Go?

Asked on Oct 17, 2025

Answer

Goroutines in Go are more lightweight than OS threads because they are managed by the Go runtime, which allows them to have a smaller memory footprint and faster context switching. The Go scheduler multiplexes thousands of goroutines onto a smaller number of OS threads, optimizing resource usage and enabling efficient concurrency.

Example Concept: Goroutines are lightweight because they start with a small stack size (typically 2KB) that grows and shrinks dynamically, unlike OS threads that require a fixed stack size (usually 1MB). The Go runtime handles scheduling, allowing for quick context switches between goroutines without involving the OS kernel, reducing overhead and improving performance for concurrent applications.

Additional Comment:

Goroutines are created using the "go" keyword, making it easy to run functions concurrently.
The Go runtime's scheduler is responsible for managing goroutines, providing efficient load balancing.
Goroutines communicate via channels, which are safe and efficient for passing data between them.
Unlike OS threads, goroutines do not require a separate system call to switch contexts, reducing latency.

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