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KAFKA-6752: Enable unclean leader election metric #4838

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Merged
junrao merged 2 commits into from
Apr 11, 2018
Merged

KAFKA-6752: Enable unclean leader election metric #4838

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KAFKA-6752: Enable unclean leader election metric
omkreddy Apr 8, 2018
4441b9d
Address review comments
omkreddy Apr 11, 2018
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5 changes: 3 additions & 2 deletions core/src/main/scala/kafka/controller/PartitionStateMachine.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -362,7 +362,7 @@ class PartitionStateMachine(config: KafkaConfig,
if (leaderIsrAndControllerEpochOpt.nonEmpty) {
val leaderIsrAndControllerEpoch = leaderIsrAndControllerEpochOpt.get
val isr = leaderIsrAndControllerEpoch.leaderAndIsr.isr
val leaderOpt = PartitionLeaderElectionAlgorithms.offlinePartitionLeaderElection(assignment, isr, liveReplicas.toSet, uncleanLeaderElectionEnabled)
val leaderOpt = PartitionLeaderElectionAlgorithms.offlinePartitionLeaderElection(assignment, isr, liveReplicas.toSet, uncleanLeaderElectionEnabled, controllerContext)
val newLeaderAndIsrOpt = leaderOpt.map { leader =>
val newIsr = if (isr.contains(leader)) isr.filter(replica => controllerContext.isReplicaOnline(replica, partition))
else List(leader)
Expand Down Expand Up @@ -435,9 +435,10 @@ class PartitionStateMachine(config: KafkaConfig,
}

object PartitionLeaderElectionAlgorithms {
def offlinePartitionLeaderElection(assignment: Seq[Int], isr: Seq[Int], liveReplicas: Set[Int], uncleanLeaderElectionEnabled: Boolean): Option[Int] = {
def offlinePartitionLeaderElection(assignment: Seq[Int], isr: Seq[Int], liveReplicas: Set[Int], uncleanLeaderElectionEnabled: Boolean, controllerContext: ControllerContext): Option[Int] = {
assignment.find(id => liveReplicas.contains(id) && isr.contains(id)).orElse {
if (uncleanLeaderElectionEnabled) {
controllerContext.stats.uncleanLeaderElectionRate.mark()

@junrao junrao Apr 10, 2018

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We probably only want to mark the metric if assignment.find(liveReplicas.contains) is not empty.

@omkreddy omkreddy Apr 11, 2018

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@junrao Thanks for the review. Updated the PR.

assignment.find(liveReplicas.contains)
} else {
None
Expand Down
26 changes: 19 additions & 7 deletions core/src/test/scala/unit/kafka/controller/PartitionLeaderElectionAlgorithmsTest.scala
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Expand Up @@ -17,10 +17,17 @@
package kafka.controller

import org.junit.Assert._
import org.junit.Test
import org.junit.{Before, Test}
import org.scalatest.junit.JUnitSuite

class PartitionLeaderElectionAlgorithmsTest extends JUnitSuite {
private var controllerContext: ControllerContext = null

@Before
def setUp(): Unit = {
controllerContext = new ControllerContext
controllerContext.stats.removeMetric("UncleanLeaderElectionsPerSec")
}

@Test
def testOfflinePartitionLeaderElection(): Unit = {
Expand All @@ -30,7 +37,8 @@ class PartitionLeaderElectionAlgorithmsTest extends JUnitSuite {
val leaderOpt = PartitionLeaderElectionAlgorithms.offlinePartitionLeaderElection(assignment,
isr,
liveReplicas,
uncleanLeaderElectionEnabled = false)
uncleanLeaderElectionEnabled = false,
controllerContext)
assertEquals(Option(4), leaderOpt)
}

Expand All @@ -42,9 +50,12 @@ class PartitionLeaderElectionAlgorithmsTest extends JUnitSuite {
val leaderOpt = PartitionLeaderElectionAlgorithms.offlinePartitionLeaderElection(assignment,
isr,
liveReplicas,
uncleanLeaderElectionEnabled = false)
uncleanLeaderElectionEnabled = false,
controllerContext)
assertEquals(None, leaderOpt)
assertEquals(0, controllerContext.stats.uncleanLeaderElectionRate.count())
}

@Test
def testOfflinePartitionLeaderElectionLastIsrOfflineUncleanLeaderElectionEnabled(): Unit = {
val assignment = Seq(2, 4)
Expand All @@ -53,19 +64,20 @@ class PartitionLeaderElectionAlgorithmsTest extends JUnitSuite {
val leaderOpt = PartitionLeaderElectionAlgorithms.offlinePartitionLeaderElection(assignment,
isr,
liveReplicas,
uncleanLeaderElectionEnabled = true)
uncleanLeaderElectionEnabled = true,
controllerContext)
assertEquals(Option(4), leaderOpt)
assertEquals(1, controllerContext.stats.uncleanLeaderElectionRate.count())
}

@Test
def testReassignPartitionLeaderElection(): Unit = {
val reassignment = Seq(2, 4)
val isr = Seq(2, 4)
val liveReplicas = Set(4)
val leaderOpt = PartitionLeaderElectionAlgorithms.offlinePartitionLeaderElection(reassignment,
val leaderOpt = PartitionLeaderElectionAlgorithms.reassignPartitionLeaderElection(reassignment,
isr,
liveReplicas,
uncleanLeaderElectionEnabled = false)
liveReplicas)
assertEquals(Option(4), leaderOpt)
}

Expand Down
14 changes: 12 additions & 2 deletions core/src/test/scala/unit/kafka/integration/UncleanLeaderElectionTest.scala
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Expand Up @@ -191,12 +191,17 @@ class UncleanLeaderElectionTest extends ZooKeeperTestHarness {
produceMessage(servers, topic, "second")
assertEquals(List("first", "second"), consumeAllMessages(topic))

//remove any previous unclean election metric
servers.map(server => server.kafkaController.controllerContext.stats.removeMetric("UncleanLeaderElectionsPerSec"))

// shutdown leader and then restart follower
servers.filter(server => server.config.brokerId == leaderId).map(server => shutdownServer(server))
servers.filter(server => server.config.brokerId == followerId).map(server => server.startup())
val followerServer = servers.find(_.config.brokerId == followerId).get
followerServer.startup()

// wait until new leader is (uncleanly) elected
waitUntilLeaderIsElectedOrChanged(zkClient, topic, partitionId, newLeaderOpt = Some(followerId))
assertEquals(1, followerServer.kafkaController.controllerContext.stats.uncleanLeaderElectionRate.count())

produceMessage(servers, topic, "third")

Expand Down Expand Up @@ -224,12 +229,17 @@ class UncleanLeaderElectionTest extends ZooKeeperTestHarness {
produceMessage(servers, topic, "second")
assertEquals(List("first", "second"), consumeAllMessages(topic))

//remove any previous unclean election metric
servers.map(server => server.kafkaController.controllerContext.stats.removeMetric("UncleanLeaderElectionsPerSec"))

// shutdown leader and then restart follower
servers.filter(server => server.config.brokerId == leaderId).map(server => shutdownServer(server))
servers.filter(server => server.config.brokerId == followerId).map(server => server.startup())
val followerServer = servers.find(_.config.brokerId == followerId).get
followerServer.startup()

// verify that unclean election to non-ISR follower does not occur
waitUntilLeaderIsElectedOrChanged(zkClient, topic, partitionId, newLeaderOpt = Some(-1))
assertEquals(0, followerServer.kafkaController.controllerContext.stats.uncleanLeaderElectionRate.count())

// message production and consumption should both fail while leader is down
try {
Expand Down