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backoff runtime errors in kubelet sync loop #60246

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Feb 27, 2018
Merged

backoff runtime errors in kubelet sync loop #60246

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13 changes: 12 additions & 1 deletion pkg/kubelet/kubelet.go
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,7 @@ import (
"context"
"crypto/tls"
"fmt"
"math"
"net"
"net/http"
"net/url"
Expand Down Expand Up @@ -1759,12 +1760,22 @@ func (kl *Kubelet) syncLoop(updates <-chan kubetypes.PodUpdate, handler SyncHand
housekeepingTicker := time.NewTicker(housekeepingPeriod)
defer housekeepingTicker.Stop()
plegCh := kl.pleg.Watch()
const (
base = 100 * time.Millisecond
max = 5 * time.Second
factor = 2
)
duration := base
for {
if rs := kl.runtimeState.runtimeErrors(); len(rs) != 0 {
glog.Infof("skipping pod synchronization - %v", rs)
time.Sleep(5 * time.Second)
// exponential backoff
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Could wait.ExponentialBackoff be used here?

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Unfortunately wait.ExponentialBackoff exits after a fixed number of steps, while we want to loop forever if necessary.

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I'm not sure about this. Even though you check aggressively here, the other part which updates runtimeErrors still works at its original rate, e.g. updateRuntimeUp is still called every 5 seconds...

I can imagine this may help in some way, but are we sure this is the right place to put the backoff?

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This helps the generic case of runtimeErrors. We can certainly add more specific backoffs and/or implement a channel-signaling mechanism in the future to further improve startup performance.

time.Sleep(duration)
duration = time.Duration(math.Min(float64(max), factor*float64(duration)))
continue
}
// reset backoff if we have a success
duration = base

kl.syncLoopMonitor.Store(kl.clock.Now())
if !kl.syncLoopIteration(updates, handler, syncTicker.C, housekeepingTicker.C, plegCh) {
Expand Down