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