v.io/x/lib/nsync: fix flaky deadline test in condition variables
The tests TestCVDeadline and TestCVCancel use time, since they are
testing a time-dependent feature of condition variables. They
sometimes fail because the scheduler fails to run threads promptly.
This change count how often they miss their deadlines, and fails
the test only if they miss sufficiently several times.
Change-Id: Id7d6032f1e569abe24a6a67f699516c727be511c
diff --git a/nsync/cv_test.go b/nsync/cv_test.go
index 325f861..d546993 100644
--- a/nsync/cv_test.go
+++ b/nsync/cv_test.go
@@ -186,9 +186,11 @@
var cv nsync.CV
// The following two values control how aggressively we police the timeout.
- var tooEarly time.Duration = 1 * time.Millisecond
- var tooLate time.Duration = 35 * time.Millisecond // longer, to accommodate scheduling delays
+ const tooEarly time.Duration = 1 * time.Millisecond
+ const tooLate time.Duration = 35 * time.Millisecond // longer, to accommodate scheduling delays
+ const tooLateAllowed int = 3 // number of iterations permitted to violate tooLate
+ var tooLateViolations int
mu.Lock()
for i := 0; i != 50; i++ {
startTime := time.Now()
@@ -201,10 +203,13 @@
t.Errorf("cvWait() returned %v too early", expectedEndTime.Sub(endTime))
}
if endTime.After(expectedEndTime.Add(tooLate)) {
- t.Errorf("cvWait() returned %v too late", endTime.Sub(expectedEndTime))
+ tooLateViolations++
}
}
mu.Unlock()
+ if tooLateViolations > tooLateAllowed {
+ t.Errorf("cvWait() returned too late %d times", tooLateViolations)
+ }
}
// TestCVCancel() checks cancellations on a CV WaitWithDeadline().
@@ -215,11 +220,13 @@
// The loops below cancel after 87 milliseconds, like the timeout tests above.
// The following two values control how aggressively we police the timeout.
- var tooEarly time.Duration = 1 * time.Millisecond
- var tooLate time.Duration = 35 * time.Millisecond // longer, to accommodate scheduling delays
+ const tooEarly time.Duration = 1 * time.Millisecond
+ const tooLate time.Duration = 35 * time.Millisecond // longer, to accommodate scheduling delays
+ const tooLateAllowed int = 3 // number of iterations permitted to violate tooLate
var futureTime time.Time = time.Now().Add(1 * time.Hour) // a future time, to test cancels with pending timeout
+ var tooLateViolations int
mu.Lock()
for i := 0; i != 50; i++ {
startTime := time.Now()
@@ -236,7 +243,7 @@
t.Errorf("cvWait() returned %v too early", expectedEndTime.Sub(endTime))
}
if endTime.After(expectedEndTime.Add(tooLate)) {
- t.Errorf("cvWait() returned %v too late", endTime.Sub(expectedEndTime))
+ tooLateViolations++
}
// Check that an already cancelled wait returns immediately.
@@ -249,8 +256,11 @@
t.Errorf("cvWait() returned %v too early", endTime.Sub(startTime))
}
if endTime.After(startTime.Add(tooLate)) {
- t.Errorf("cvWait() returned %v too late", endTime.Sub(startTime))
+ tooLateViolations++
}
}
mu.Unlock()
+ if tooLateViolations > tooLateAllowed {
+ t.Errorf("cvWait() returned too late %d times", tooLateViolations)
+ }
}
