os/exec: in TestContextCancel, dump goroutines on failure
If this test fails, we want to know exactly what the os/exec
goroutines are doing. Panicking gives us a goroutine dump,
whereas t.Fatal does not.
While we're here, use exponential backoff instead of a hard-coded 1ms
sleep. We want to give the OS enough time to actually terminate the
subprocess.
For #42061
Change-Id: I3d50a71ac314853c68a935218e7f97ce18b08b5b
Reviewed-on: https://go-review.googlesource.com/c/go/+/368317
Trust: Bryan C. Mills <bcmills@google.com>
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
diff --git a/src/os/exec/exec_test.go b/src/os/exec/exec_test.go
index 6172c78..81de018 100644
--- a/src/os/exec/exec_test.go
+++ b/src/os/exec/exec_test.go
@@ -954,6 +954,10 @@
}
func TestContextCancel(t *testing.T) {
+ // To reduce noise in the final goroutine dump,
+ // let other parallel tests complete if possible.
+ t.Parallel()
+
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
c := helperCommandContext(t, ctx, "cat")
@@ -978,14 +982,25 @@
// Calling cancel should have killed the process, so writes
// should now fail. Give the process a little while to die.
start := time.Now()
+ delay := 1 * time.Millisecond
for {
if _, err := io.WriteString(stdin, "echo"); err != nil {
break
}
+
if time.Since(start) > time.Minute {
- t.Fatal("canceling context did not stop program")
+ // Panic instead of calling t.Fatal so that we get a goroutine dump.
+ // We want to know exactly what the os/exec goroutines got stuck on.
+ panic("canceling context did not stop program")
}
- time.Sleep(time.Millisecond)
+
+ // Back off exponentially (up to 1-second sleeps) to give the OS time to
+ // terminate the process.
+ delay *= 2
+ if delay > 1*time.Second {
+ delay = 1 * time.Second
+ }
+ time.Sleep(delay)
}
if err := c.Wait(); err == nil {
