package time
-import (
- "errors"
- "runtime"
-)
-
func init() {
// force US/Pacific for time zone tests
ForceUSPacificForTesting()
//
// This test has to be in internal_test.go since it fiddles with
// unexported data structures.
-func CheckRuntimeTimerOverflow() error {
+func CheckRuntimeTimerOverflow() {
// We manually create a runtimeTimer to bypass the overflow
// detection logic in NewTimer: we're testing the underlying
// runtime.addtimer function.
}
startTimer(r)
- timeout := 100 * Millisecond
- switch runtime.GOOS {
- // Allow more time for gobuilder to succeed.
- case "windows":
- timeout = Second
- case "plan9":
- // TODO(0intro): We don't know why it is needed.
- timeout = 3 * Second
- }
-
- // Start a goroutine that should send on t.C before the timeout.
+ // Start a goroutine that should send on t.C right away.
t := NewTimer(1)
defer func() {
startTimer(r)
}()
- // Try to receive from t.C before the timeout. It will succeed
- // iff the previous sleep was able to finish. We're forced to
- // spin and yield after trying to receive since we can't start
- // any more timers (they might hang due to the same bug we're
- // now testing).
- stop := Now().Add(timeout)
- for {
- select {
- case <-t.C:
- return nil // It worked!
- default:
- if Now().After(stop) {
- return errors.New("runtime timer stuck: overflow in addtimer")
- }
- // Issue 6874. This test previously called runtime.Gosched to try to yield
- // to the goroutine servicing t, however the scheduler has a bias towards the
- // previously running goroutine in an idle system. Combined with high load due
- // to all CPUs busy running tests t's goroutine could be delayed beyond the
- // timeout window.
- //
- // Calling runtime.GC() reduces the worst case lantency for scheduling t by 20x
- // under the current Go 1.3 scheduler.
- runtime.GC()
- }
- }
+ // If the test fails, we will hang here until the timeout in the testing package
+ // fires, which is 10 minutes. It would be nice to catch the problem sooner,
+ // but there is no reliable way to guarantee that timerproc schedules without
+ // doing something involving timerproc itself. Previous failed attempts have
+ // tried calling runtime.Gosched and runtime.GC, but neither is reliable.
+ // So we fall back to hope: We hope we don't hang here.
+ <-t.C
}