What is Golang’s gc?

The operating environment of this article: Windows 10 system, Go1.20.4 version, Dell G3 computer.

Golang’s gc refers to the garbage collection (Garbage Collection) mechanism. Garbage collection is an automatic memory management technology that is responsible for automatically detecting and releasing no longer used memory resources when the program is running, thereby reducing the programmer's burden of manual memory management.

Golang garbage collection mechanism is a concurrent garbage collector based on the mark-sweep algorithm. It uses a three-color marking method to divide objects in the heap into three states: white, gray and black. White indicates that the object has not been scanned, gray indicates that the object has been scanned but its reference objects have not been scanned, and black indicates that both the object and its reference objects have been scanned.

Golang’s garbage collector has the following characteristics:

Concurrency mark: When garbage collection is performed, the garbage collector will execute concurrently with the application, minimizing the impact of the program. It uses a concurrent marking algorithm to mark objects in the heap through multiple threads to improve the efficiency of garbage collection.

Three-color marking: Golang's garbage collector uses a three-color marking method to divide objects into different states to avoid missing and mislabeling. Through the conversion of three states: white, gray and black, it is ensured that all objects can be marked and recycled correctly.

Incremental marking: In order to reduce the pause time of garbage collection, Golang's garbage collector uses an incremental marking algorithm. It divides the marking process into multiple stages, inserting some application execution time between each stage to reduce interference to the application.

Memory allocation: Golang’s garbage collector is also responsible for memory allocation and release. It uses a generational algorithm to divide the heap into different generations, and each generation has its own recycling strategy. Through generational recycling, objects with different life cycles can be recycled more efficiently.

Adjustable parameters: Golang's garbage collector provides some adjustable parameters to optimize according to different application scenarios. For example, the frequency and threshold of garbage collection can be adjusted by setting GOGC parameters to balance the efficiency of garbage collection and the impact on the application.

Summary

Golang’s garbage collector is an efficient, concurrent and reliable automatic memory management technology. It realizes automatic memory recycling through algorithms such as concurrent marking, three-color marking, incremental marking, and generational recycling, reducing the burden on programmers and improving application performance and stability.

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