[GitHub] markusthoemmes closed pull request #3272: improve loadbalancer's schedule algorithm

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markusthoemmes closed pull request #3272: improve loadbalancer's schedule algorithm
URL: https://github.com/apache/incubator-openwhisk/pull/3272
 
 
   

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diff --git a/core/controller/src/main/scala/whisk/core/loadBalancer/ContainerPoolBalancer.scala b/core/controller/src/main/scala/whisk/core/loadBalancer/ContainerPoolBalancer.scala
index 193ed8da9f..a5327b0907 100644
--- a/core/controller/src/main/scala/whisk/core/loadBalancer/ContainerPoolBalancer.scala
+++ b/core/controller/src/main/scala/whisk/core/loadBalancer/ContainerPoolBalancer.scala
@@ -18,6 +18,7 @@
 package whisk.core.loadBalancer
 
 import java.nio.charset.StandardCharsets
+import java.util.concurrent.ThreadLocalRandom
 
 import akka.actor.{ActorSystem, Props}
 import akka.cluster.Cluster
@@ -343,7 +344,11 @@ object ContainerPoolBalancer extends LoadBalancerProvider {
         .find(_._3 < invokerBusyThreshold)
         .orElse(invokerProgression.find(_._3 < invokerBusyThreshold * 2))
         .orElse(invokerProgression.find(_._3 < invokerBusyThreshold * 3))
-        .orElse(invokerProgression.headOption)
+        .orElse(
+          if (invokerProgression.isEmpty)
+            None
+          else
+            Some(invokerProgression(ThreadLocalRandom.current().nextInt(invokerProgression.size))))
         .map(_._1)
     } else None
   }
diff --git a/tests/src/test/scala/whisk/core/loadBalancer/test/ContainerPoolBalancerObjectTests.scala b/tests/src/test/scala/whisk/core/loadBalancer/test/ContainerPoolBalancerObjectTests.scala
index 60eda84a79..fd3252d1c8 100644
--- a/tests/src/test/scala/whisk/core/loadBalancer/test/ContainerPoolBalancerObjectTests.scala
+++ b/tests/src/test/scala/whisk/core/loadBalancer/test/ContainerPoolBalancerObjectTests.scala
@@ -143,11 +143,14 @@ class ContainerPoolBalancerObjectTests extends FlatSpec with Matchers {
     ContainerPoolBalancer.schedule(invs, 16, hash) shouldBe Some(InstanceId(0))
   }
 
-  it should "choose the home invoker if all invokers are overloaded even above the muliplied threshold" in {
-    val invs = IndexedSeq((InstanceId(0), Healthy, 51), (InstanceId(1), Healthy, 50), (InstanceId(2), Healthy, 49))
-    val hash = 0 // home is 0, stepsize is 1
-
-    ContainerPoolBalancer.schedule(invs, 16, hash) shouldBe Some(InstanceId(0))
+  it should "choose the random invoker if all invokers are overloaded even above the muliplied threshold" in {
+    val invs = IndexedSeq((InstanceId(0), Healthy, 33), (InstanceId(1), Healthy, 33), (InstanceId(2), Healthy, 33))
+    val invokerBusyThreshold = 11
+    val hash = 0
+    val bruteResult = (0 to 100) map { _ =>
+      ContainerPoolBalancer.schedule(invs, invokerBusyThreshold, hash).get.toInt
+    }
+    bruteResult should contain allOf (0, 1, 2)
   }
 
   it should "transparently work with partitioned sets of invokers" in {


 

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