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JitterUntil should reuse Timer instead of allocating

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Many of our core loops rotate around JitterUntil, which means we create
a lot of garbage at steady state for timers. Add proper timer reuse in
this loop.
This commit is contained in:
Clayton Coleman 2017-03-19 19:01:14 -04:00
parent ae6a5d2bf3
commit 01a23fd0bc
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GPG Key ID: 3D16906B4F1C5CB3
1 changed files with 19 additions and 4 deletions
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23
staging/src/k8s.io/apimachinery/pkg/util/wait/wait.go
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@ -73,8 +73,10 @@ func NonSlidingUntil(f func(), period time.Duration, stopCh <-chan struct{}) {
// Close stopCh to stop. f may not be invoked if stop channel is already
// closed. Pass NeverStop to if you don't want it stop.
func JitterUntil(f func(), period time.Duration, jitterFactor float64, sliding bool, stopCh <-chan struct{}) {
for {
var t *time.Timer
var sawTimeout bool
for {
select {
case <-stopCh:
return
@ -86,9 +88,8 @@ func JitterUntil(f func(), period time.Duration, jitterFactor float64, sliding b
jitteredPeriod = Jitter(period, jitterFactor)
}
var t *time.Timer
if !sliding {
t = time.NewTimer(jitteredPeriod)
t = resetOrReuseTimer(t, jitteredPeriod, sawTimeout)
}
func() {
@ -97,7 +98,7 @@ func JitterUntil(f func(), period time.Duration, jitterFactor float64, sliding b
}()
if sliding {
t = time.NewTimer(jitteredPeriod)
t = resetOrReuseTimer(t, jitteredPeriod, sawTimeout)
}
// NOTE: b/c there is no priority selection in golang
@ -109,6 +110,7 @@ func JitterUntil(f func(), period time.Duration, jitterFactor float64, sliding b
case <-stopCh:
return
case <-t.C:
sawTimeout = true
}
}
}
@ -330,3 +332,16 @@ func poller(interval, timeout time.Duration) WaitFunc {
return ch
})
}
// resetOrReuseTimer avoids allocating a new timer if one is already in use.
// Not safe for multiple threads.
func resetOrReuseTimer(t *time.Timer, d time.Duration, sawTimeout bool) *time.Timer {
if t == nil {
return time.NewTimer(d)
}
if !t.Stop() && !sawTimeout {
<-t.C
}
t.Reset(d)
return t
}