How Does Golang Gc Work So Fast

Go Programming

As a developer who has worked extensively with Golang, I have always been fascinated by the efficiency and speed of its garbage collector (GC) compared to other programming languages. In this article, I’ll delve into the inner workings of Golang’s GC and explore why it is able to work so fast.

Understanding Golang Garbage Collection

Golang’s garbage collection is a concurrent and parallel process, which means it can run alongside the application code without causing significant interruptions. This is achieved through a technique known as “tricolor marking” where objects are divided into three colors: white, grey, and black. The GC starts with all objects marked white, and during the marking phase, it traverses the object graph, marking objects grey when they are discovered and then black when their references have been processed. This allows the GC to efficiently identify and collect unreachable memory without halting the application for extended periods.

Furthermore, Golang’s GC is generational, meaning it divides memory into multiple generations based on the age of the objects. Younger objects are more likely to be garbage, so Golang’s GC focuses primarily on collecting garbage from the younger generations, which significantly reduces the amount of memory that needs to be scanned.

Memory Management in Golang

One of the key factors contributing to Golang’s fast GC is its efficient memory management. Golang uses a technique called “write barrier” to keep track of pointer updates. When a pointer to an object is updated, the write barrier ensures that the GC is aware of the change, making the marking phase more effective and reducing the need for extensive scanning of memory.

Golang also employs a technique called “stack copying” during the garbage collection process. This involves copying the entire stack to a new location, which allows the GC to easily identify and update pointers, leading to faster and more efficient memory reclamation.


In conclusion, Golang’s garbage collection works so fast due to its concurrent and parallel nature, tricolor marking, generational approach, efficient memory management, and clever techniques like write barrier and stack copying. These factors collectively contribute to Golang’s ability to efficiently reclaim memory without causing significant performance overhead. As a developer, understanding the inner workings of Golang’s GC can provide valuable insights into writing efficient and scalable applications.