Add backoff package and fix Consul CPU usage (#635)
* Add backoff package
Justification for jitter and growth factor:
https://aws.amazon.com/blogs/architecture/exponential-backoff-and-jitter/.
Add backoff to the Consul instancer loop.
Fixes https://github.com/go-kit/kit/issues/627.
* Revert "Add backoff package"
This reverts commit 924501ae1fcfadaa27593e9c019283412c513928.
* Get rid of external package and update exponential
* Add instancer backoff
* Fix old exponential name
* Add doc comment
* Fixup & respond to review
Nico Tonozzi authored 6 years ago
Peter Bourgon committed 6 years ago
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import (
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"fmt"
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"io"
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"time"
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consul "github.com/hashicorp/consul/api"
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"github.com/go-kit/kit/log"
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"github.com/go-kit/kit/sd"
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"github.com/go-kit/kit/sd/internal/instance"
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"github.com/go-kit/kit/util/conn"
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)
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const defaultIndex = 0
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var (
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instances []string
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err error
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d time.Duration = 10 * time.Millisecond
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)
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for {
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instances, lastIndex, err = s.getInstances(lastIndex, s.quitc)
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return // stopped via quitc
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case err != nil:
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s.logger.Log("err", err)
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time.Sleep(d)
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d = conn.Exponential(d)
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s.cache.Update(sd.Event{Err: err})
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default:
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s.cache.Update(sd.Event{Instances: instances})
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d = 10 * time.Millisecond
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}
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}
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}
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import (
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"errors"
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"math/rand"
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"net"
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"time"
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case conn = <-connc:
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if conn == nil {
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// didn't work
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backoff = exponential(backoff) // wait longer
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backoff = Exponential(backoff) // wait longer
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reconnectc = m.after(backoff) // try again
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} else {
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// worked!
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return conn
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}
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func exponential(d time.Duration) time.Duration {
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// Exponential takes a duration and returns another one that is twice as long, +/- 50%. It is
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// used to provide backoff for operations that may fail and should avoid thundering herds.
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// See https://aws.amazon.com/blogs/architecture/exponential-backoff-and-jitter/ for rationale
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func Exponential(d time.Duration) time.Duration {
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d *= 2
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jitter := rand.Float64() + 0.5
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d = time.Duration(int64(float64(d.Nanoseconds()) * jitter))
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if d > time.Minute {
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d = time.Minute
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}
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return d
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}
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// ErrConnectionUnavailable is returned by the Manager's Write method when the
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