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go/test/chan/select2.go
Carl Shapiro 1c45f98fa3 test/chan: avoid wrap-around in memstats comparison
The select2.go test assumed that the memory allocated between
its two samplings of runtime.ReadMemStats is strictly
increasing.  To avoid failing the tests when this is not true,
a greater-than check is introduced before computing the
difference in allocated memory.

R=golang-dev, r, cshapiro
CC=golang-dev
https://golang.org/cl/13701046
2013-09-20 17:27:56 -07:00

55 lines
1.0 KiB
Go

// run
// Copyright 2010 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Test that selects do not consume undue memory.
package main
import "runtime"
func sender(c chan int, n int) {
for i := 0; i < n; i++ {
c <- 1
}
}
func receiver(c, dummy chan int, n int) {
for i := 0; i < n; i++ {
select {
case <-c:
// nothing
case <-dummy:
panic("dummy")
}
}
}
func main() {
runtime.MemProfileRate = 0
c := make(chan int)
dummy := make(chan int)
// warm up
go sender(c, 100000)
receiver(c, dummy, 100000)
runtime.GC()
memstats := new(runtime.MemStats)
runtime.ReadMemStats(memstats)
alloc := memstats.Alloc
// second time shouldn't increase footprint by much
go sender(c, 100000)
receiver(c, dummy, 100000)
runtime.GC()
runtime.ReadMemStats(memstats)
// Be careful to avoid wraparound.
if memstats.Alloc > alloc && memstats.Alloc-alloc > 1.1e5 {
println("BUG: too much memory for 100,000 selects:", memstats.Alloc-alloc)
}
}