What is escape analysis in Go?
Escape analysis is a compile-time optimization where the Go compiler decides whether a variable can live on the stack (fast, automatically freed) or must be heap-allocated (GC-managed) based on its lifetime.
The compiler performs escape analysis to minimize heap allocations, reducing GC pressure. A variable escapes to the heap when its lifetime exceeds the function frame or when its size is dynamically determined.
- 1
Returned by pointer: the caller holds the reference, variable must outlive the function
- 2
Stored in an interface: concrete type is hidden, compiler cannot track lifetime statically
- 3
Captured by a goroutine closure: goroutine may outlive the creating function
- 4
Size unknown at compile time: dynamic slices and maps
- 5
Too large for the stack: objects exceeding the stack size limit