From 325664766811cdac02735f97895fef6c4aa7034f Mon Sep 17 00:00:00 2001
From: "Timothy St. Clair" <tstclair@redhat.com>
Date: Fri, 15 Jan 2016 13:54:26 -0600
Subject: [PATCH] Add jitter to housekeeping interval

---
 manager/container.go | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/manager/container.go b/manager/container.go
index 07667218..b6706186 100644
--- a/manager/container.go
+++ b/manager/container.go
@@ -19,6 +19,7 @@ import (
 	"fmt"
 	"io/ioutil"
 	"math"
+	"math/rand"
 	"os/exec"
 	"path"
 	"regexp"
@@ -78,6 +79,17 @@ type containerData struct {
 	collectorManager collector.CollectorManager
 }
 
+// jitter returns a time.Duration between duration and duration + maxFactor * duration,
+// to allow clients to avoid converging on periodic behavior.  If maxFactor is 0.0, a
+// suggested default value will be chosen.
+func jitter(duration time.Duration, maxFactor float64) time.Duration {
+	if maxFactor <= 0.0 {
+		maxFactor = 1.0
+	}
+	wait := duration + time.Duration(rand.Float64()*maxFactor*float64(duration))
+	return wait
+}
+
 func (c *containerData) Start() error {
 	go c.housekeeping()
 	return nil
@@ -356,7 +368,7 @@ func (self *containerData) nextHousekeeping(lastHousekeeping time.Time) time.Tim
 		}
 	}
 
-	return lastHousekeeping.Add(self.housekeepingInterval)
+	return lastHousekeeping.Add(jitter(self.housekeepingInterval, 1.0))
 }
 
 // TODO(vmarmol): Implement stats collecting as a custom collector.