Make TestApply_parallelism more reliable

Wait for our expected number of goroutines to be staged and ready, then
allow Run() to complete. Use a high-water-mark counter to ensure we
never exceeded the max expected concurrent goroutines at any point
during the run.
This commit is contained in:
James Bardin 2016-10-17 18:26:16 -04:00
parent f86198c155
commit 54d50c90b1
1 changed files with 66 additions and 18 deletions

View File

@ -12,7 +12,6 @@ import (
"reflect"
"strings"
"sync"
"sync/atomic"
"testing"
"time"
@ -59,24 +58,57 @@ func TestApply(t *testing.T) {
}
}
// high water mark counter
type hwm struct {
sync.Mutex
val int
max int
}
func (t *hwm) Inc() {
t.Lock()
defer t.Unlock()
t.val++
if t.val > t.max {
t.max = t.val
}
}
func (t *hwm) Dec() {
t.Lock()
defer t.Unlock()
t.val--
}
func (t *hwm) Max() int {
t.Lock()
defer t.Unlock()
return t.max
}
func TestApply_parallelism(t *testing.T) {
provider := testProvider()
statePath := testTempFile(t)
par := 4
// This blocks all the appy functions. We close it when we exit so
// they end quickly after this test finishes.
block := make(chan struct{})
defer close(block)
// signal how many goroutines have started
started := make(chan int, 100)
runCount := &hwm{}
var runCount uint64
provider.ApplyFn = func(
i *terraform.InstanceInfo,
s *terraform.InstanceState,
d *terraform.InstanceDiff) (*terraform.InstanceState, error) {
// Increment so we're counting parallelism
atomic.AddUint64(&runCount, 1)
// Block until we're done
started <- 1
runCount.Inc()
defer runCount.Dec()
// Block here to stage up our max number of parallel instances
<-block
return nil, nil
@ -90,30 +122,46 @@ func TestApply_parallelism(t *testing.T) {
},
}
par := uint64(5)
args := []string{
"-state", statePath,
fmt.Sprintf("-parallelism=%d", par),
testFixturePath("parallelism"),
}
// Run in a goroutine. We still try to catch any errors and
// get them on the error channel.
errCh := make(chan string, 1)
// Run in a goroutine. We can get any errors from the ui.OutputWriter
doneCh := make(chan int, 1)
go func() {
if code := c.Run(args); code != 0 {
errCh <- ui.OutputWriter.String()
}
doneCh <- c.Run(args)
}()
timeout := time.After(5 * time.Second)
// ensure things are running
for i := 0; i < par; i++ {
select {
case <-time.After(1000 * time.Millisecond):
case err := <-errCh:
t.Fatalf("err: %s", err)
case <-timeout:
t.Fatal("timeout waiting for all goroutines to start")
case <-started:
}
}
// a little extra sleep, since we can't ensure all goroutines from the walk have
// really started
time.Sleep(100 * time.Millisecond)
close(block)
select {
case res := <-doneCh:
if res != 0 {
t.Fatal(ui.OutputWriter.String())
}
case <-timeout:
t.Fatal("timeout waiting from Run()")
}
// The total in flight should equal the parallelism
if rc := atomic.LoadUint64(&runCount); rc != par {
t.Fatalf("Expected parallelism: %d, got: %d", par, rc)
if runCount.Max() != par {
t.Fatalf("Expected parallelism: %d, got: %d", par, runCount.Max())
}
}