Skip to content

Golang Garbage Collection (GC)

The Go programming language employs a concurrent garbage collector (GC) to manage memory. This means that memory management in Go is handled automatically by the runtime, relieving developers from manual memory management tasks.

Key Features of Golang GC:

  • Concurrent Operation:

  • The garbage collector runs concurrently with the Go program itself, which means it operates alongside the main program threads without significant interruption.

  • Tricolor Mark and Sweep:

  • The GC uses a tricolor algorithm to perform its operations. It divides objects into three color categories: white, grey, and black.

    • White: Unvisited objects
    • Grey: Visited but not yet marked children
    • Black: Visited and marked, with all children also marked

  • Tri-Color Invariant:

  • At any point in time, there are no white-to-black edges. In other words, there are no pointers from marked objects to unmarked objects.

GC Phases:

  1. Mark Phase:
  • Traverses the object graph, starting from the roots (global variables, stack frames, etc.), marking reachable objects as grey.
  1. Sweep Phase:
  • Frees memory of unmarked (white) objects.
  1. Scavenge Phase (Optional): - This phase is specific to Go’s two-generational garbage collector. It focuses on collecting short-lived objects (young generation) quickly.

Generational Garbage Collection (Optional):

Go employs a two-generational garbage collector which divides objects into young and old generations.

  • Young Generation:

  • Contains recently allocated objects. This generation is garbage collected more frequently (scavenged) as short-lived objects tend to die young.

  • Old Generation:

  • Contains objects that have survived multiple garbage collection cycles. It is garbage collected less frequently.

GC Tuning (Advanced):

  • Go provides some knobs and options to fine-tune the garbage collector. However, it’s important to note that manual tuning is rarely necessary for most applications.

  • If you do need to fine-tune, consider adjusting GOGC environment variables or using runtime functions like debug.SetGCPercent().

Benefits of Concurrent GC in Go:

  • Automatic Memory Management:

  • Developers don’t need to manually allocate or free memory, reducing the risk of memory leaks.

  • Reduced GC Pauses:

  • The concurrent nature of the GC means that it can work alongside the main program threads, minimizing the impact on application responsiveness.

  • Improved Developer Productivity:

  • Developers can focus more on writing code and less on memory management intricacies.

  • Reduced Risk of Memory Bugs:

  • With manual memory management comes the risk of bugs like segmentation faults and memory leaks, which are largely mitigated in Go.