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test/chan/doubleselect: fix various races

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There were duplicate closes and missing closes,
with the result that the program was rarely testing
as much as it seemed to be.  Now it finishes.

R=r
CC=golang-dev
https://golang.org/cl/4008046
This commit is contained in:
Russ Cox 2011-01-21 15:06:44 -05:00
parent 5b5a674b46
commit 0a5fc261b6
1 changed files with 19 additions and 17 deletions
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36
test/chan/doubleselect.go
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@ -21,6 +21,8 @@ var iterations *int = flag.Int("n", 100000, "number of iterations")
func sender(n int, c1, c2, c3, c4 chan<- int) {
defer close(c1)
defer close(c2)
defer close(c3)
defer close(c4)
for i := 0; i < n; i++ {
select {
@ -35,26 +37,18 @@ func sender(n int, c1, c2, c3, c4 chan<- int) {
// mux receives the values from sender and forwards them onto another channel.
// It would be simplier to just have sender's four cases all be the same
// channel, but this doesn't actually trigger the bug.
func mux(out chan<- int, in <-chan int) {
for {
v := <-in
if closed(in) {
close(out)
break
}
func mux(out chan<- int, in <-chan int, done chan<- bool) {
for v := range in {
out <- v
}
done <- true
}
// recver gets a steam of values from the four mux's and checks for duplicates.
func recver(in <-chan int) {
seen := make(map[int]bool)
for {
v := <-in
if closed(in) {
break
}
for v := range in {
if _, ok := seen[v]; ok {
println("got duplicate value: ", v)
panic("fail")
@ -70,15 +64,23 @@ func main() {
c2 := make(chan int)
c3 := make(chan int)
c4 := make(chan int)
done := make(chan bool)
cmux := make(chan int)
go sender(*iterations, c1, c2, c3, c4)
go mux(cmux, c1)
go mux(cmux, c2)
go mux(cmux, c3)
go mux(cmux, c4)
go mux(cmux, c1, done)
go mux(cmux, c2, done)
go mux(cmux, c3, done)
go mux(cmux, c4, done)
go func() {
<-done
<-done
<-done
<-done
close(cmux)
}()
// We keep the recver because it might catch more bugs in the future.
// However, the result of the bug linked to at the top is that we'll
// end up panicing with: "throw: bad g->status in ready".
// end up panicking with: "throw: bad g->status in ready".
recver(cmux)
print("PASS\n")
}