package main import ( "bytes" "fmt" "sync" ) var pool = sync.Pool{ // New creates an object when the pool has nothing available to return. // New must return an interface{} to make it flexible. You have to cast // your type after getting it. New: func() interface{} { // Pools often contain things like *bytes.Buffer, which are // temporary and re-usable. return &bytes.Buffer{} }, } func main() { // When getting from a Pool, you need to cast s := pool.Get().(*bytes.Buffer) // We write to the object s.Write([]byte("dirty")) // Then put it back pool.Put(s) // Pools can return dirty results // Get 'another' buffer s = pool.Get().(*bytes.Buffer) // Write to it s.Write([]byte("append")) // At this point, if GC ran, this buffer *might* exist already, in // which case it will contain the bytes of the string "dirtyappend" fmt.Println(s) // So use pools wisely, and clean up after yourself s.Reset() pool.Put(s) // When you clean up, your buffer should be empty s = pool.Get().(*bytes.Buffer) // Defer your Puts to make sure you don't leak! defer pool.Put(s) s.Write([]byte("reset!")) // This prints "reset!", and not "dirtyappendreset!" fmt.Println(s) }