test: make tests deterministic with -scheduler=threads

testdata/channel.go

@@ -3,6 +3,7 @@ package main
 import (
 	"runtime"
 	"sync"
+	"sync/atomic"
 	"time"
 )
 
@@ -70,11 +71,13 @@ func main() {
 	// Test multi-receiver.
 	ch = make(chan int)
 	wg.Add(3)
-	go fastreceiver(ch)
-	go fastreceiver(ch)
-	go fastreceiver(ch)
+	var result atomic.Uint32
+	go fastreceiveradd(ch, &result)
+	go fastreceiveradd(ch, &result)
+	go fastreceiveradd(ch, &result)
 	slowsender(ch)
 	wg.Wait()
+	println("sum of sums:", result.Load())
 
 	// Test iterator style channel.
 	ch = make(chan int)
@@ -290,6 +293,16 @@ func fastreceiver(ch chan int) {
 	wg.Done()
 }
 
+func fastreceiveradd(ch chan int, result *atomic.Uint32) {
+	sum := 0
+	for i := 0; i < 2; i++ {
+		n := <-ch
+		sum += n
+	}
+	result.Add(uint32(sum))
+	wg.Done()
+}
+
 func iterator(ch chan int, top int) {
 	for i := 0; i < top; i++ {
 		ch <- i

testdata/channel.txt

@@ -12,9 +12,7 @@ received num: 8
 recv from closed channel: 0 false
 complex128: (+7.000000e+000+1.050000e+001i)
 sum of n: 149
-sum: 25
-sum: 29
-sum: 33
+sum of sums: 87
 sum(100): 4950
 deadlocking
 select no-op

testdata/goroutines.go

@@ -96,8 +96,8 @@ func acquire(m *sync.Mutex) {
 	m.Lock()
 	println("acquired mutex from goroutine")
 	time.Sleep(2 * time.Millisecond)
+	println("releasing mutex from goroutine")
 	m.Unlock()
-	println("released mutex from goroutine")
 }
 
 func sub() {

testdata/goroutines.txt

@@ -19,7 +19,7 @@ closure go call result: 1
 pre-acquired mutex
 releasing mutex
 acquired mutex from goroutine
-released mutex from goroutine
+releasing mutex from goroutine
 re-acquired mutex
 done
 called: Foo.Nowait