1 // run 2 3 // Copyright 2016 The Go Authors. All rights reserved. 4 // Use of this source code is governed by a BSD-style 5 // license that can be found in the LICENSE file. 6 // +build amd64 7 8 package main 9 10 import "runtime" 11 12 type big [10 << 20]byte 13 14 func f(x *big, start int64) { 15 if delta := inuse() - start; delta < 9<<20 { 16 println("after alloc: expected delta at least 9MB, got: ", delta) 17 } 18 runtime.KeepAlive(x) 19 x = nil 20 if delta := inuse() - start; delta > 1<<20 { 21 println("after drop: expected delta below 1MB, got: ", delta) 22 } 23 x = new(big) 24 if delta := inuse() - start; delta < 9<<20 { 25 println("second alloc: expected delta at least 9MB, got: ", delta) 26 } 27 runtime.KeepAlive(x) 28 } 29 30 func main() { 31 x := inuse() 32 f(new(big), x) 33 } 34 35 func inuse() int64 { 36 runtime.GC() 37 var st runtime.MemStats 38 runtime.ReadMemStats(&st) 39 return int64(st.Alloc) 40 } 41
