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Add backoff package and fix Consul CPU usage #635

Merged
merged 8 commits into from
Apr 2, 2018
Merged

Add backoff package and fix Consul CPU usage #635

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924501a
Add backoff package
Dec 3, 2017
12eacfb
Merge branch 'master' into n/backoff
Mar 19, 2018
0ad6586
Revert "Add backoff package"
Mar 19, 2018
99319fb
Get rid of external package and update exponential
Mar 19, 2018
8c60620
Add instancer backoff
Mar 19, 2018
10620f3
Fix old exponential name
Mar 19, 2018
9e8371f
Add doc comment
Mar 31, 2018
dc88158
Fixup & respond to review
Apr 1, 2018
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6 changes: 6 additions & 0 deletions sd/consul/instancer.go
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Original file line number Diff line number Diff line change
Expand Up @@ -3,12 +3,14 @@ package consul
import (
"fmt"
"io"
"time"

consul "github.com/hashicorp/consul/api"

"github.com/go-kit/kit/log"
"github.com/go-kit/kit/sd"
"github.com/go-kit/kit/sd/internal/instance"
"github.com/go-kit/kit/util/conn"
)

const defaultIndex = 0
Expand Down Expand Up @@ -59,6 +61,7 @@ func (s *Instancer) loop(lastIndex uint64) {
var (
instances []string
err error
d time.Duration = 10 * time.Millisecond
)
for {
instances, lastIndex, err = s.getInstances(lastIndex, s.quitc)
Expand All @@ -67,9 +70,12 @@ func (s *Instancer) loop(lastIndex uint64) {
return // stopped via quitc
case err != nil:
s.logger.Log("err", err)
time.Sleep(d)
d = conn.Exponential(d)
s.cache.Update(sd.Event{Err: err})
default:
s.cache.Update(sd.Event{Instances: instances})
d = 10 * time.Millisecond
}
}
}
Expand Down
11 changes: 9 additions & 2 deletions util/conn/manager.go
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,7 @@ package conn

import (
"errors"
"math/rand"
"net"
"time"

Expand Down Expand Up @@ -103,7 +104,7 @@ func (m *Manager) loop() {
case conn = <-connc:
if conn == nil {
// didn't work
backoff = exponential(backoff) // wait longer
backoff = Exponential(backoff) // wait longer
reconnectc = m.after(backoff) // try again
} else {
// worked!
Expand Down Expand Up @@ -132,12 +133,18 @@ func dial(d Dialer, network, address string, logger log.Logger) net.Conn {
return conn
}

func exponential(d time.Duration) time.Duration {
// Exponential takes a duration and returns another one that is twice as long, +/- 50%. It is
// used to provide backoff for operations that may fail and should avoid thundering herds.
// See https://aws.amazon.com/blogs/architecture/exponential-backoff-and-jitter/ for rationale
func Exponential(d time.Duration) time.Duration {
d *= 2
jitter := rand.Float64() + 0.5
d = time.Duration(int64(float64(d.Nanoseconds()) * jitter))
if d > time.Minute {
d = time.Minute
}
return d

}

// ErrConnectionUnavailable is returned by the Manager's Write method when the
Expand Down