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KAFKA-6054: Add 'version probing' to Kafka Streams rebalance #4636

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merged 19 commits into from
May 31, 2018
Merged

KAFKA-6054: Add 'version probing' to Kafka Streams rebalance #4636

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3f2647f
KAFKA-6054: Add Kafka Streams rebalance metadata 'version probing'
mjsax Mar 18, 2018
ef378a6
Github comments
mjsax Apr 20, 2018
a45f26b
x
mjsax Apr 20, 2018
c8484ec
Remove versionProbingFlag from TaskManager
mjsax Apr 20, 2018
0804910
Fix system test Kafka version
mjsax May 7, 2018
82a6758
Rebased
mjsax May 16, 2018
0037e74
Send empty assignment only to version-probing instance
mjsax May 20, 2018
622aa0a
Some code cleanup
mjsax May 20, 2018
a51b12d
Updates assignment strategy for version-probing phase
mjsax May 22, 2018
6793c2f
System tests
mjsax May 22, 2018
1671fe6
Do real rolling bounce test
mjsax May 23, 2018
3a7c513
Updated version probing protocol and adjusted system test
mjsax May 25, 2018
9ef1dfb
fix unit tests
mjsax May 25, 2018
6a077ec
Fix checkstyle
mjsax May 25, 2018
7b01cae
Fixed system test
mjsax May 25, 2018
e3035e8
Github comment
mjsax May 25, 2018
e6d576f
Github comments
mjsax May 30, 2018
5c0853e
Fix checkstyle
mjsax May 30, 2018
0a87bd5
fix system test
mjsax May 31, 2018
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108 changes: 91 additions & 17 deletions streams/src/main/java/org/apache/kafka/streams/StreamsConfig.java
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28 changes: 14 additions & 14 deletions streams/src/main/java/org/apache/kafka/streams/processor/internals/AssignedTasks.java
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Original file line number Diff line number Diff line change
Expand Up @@ -40,15 +40,15 @@ abstract class AssignedTasks<T extends Task> {
private final Logger log;
private final String taskTypeName;
private final TaskAction<T> commitAction;
private Map<TaskId, T> created = new HashMap<>();
private Map<TaskId, T> suspended = new HashMap<>();
private Map<TaskId, T> restoring = new HashMap<>();
private Set<TopicPartition> restoredPartitions = new HashSet<>();
private Set<TaskId> previousActiveTasks = new HashSet<>();
private final Map<TaskId, T> created = new HashMap<>();
private final Map<TaskId, T> suspended = new HashMap<>();
private final Map<TaskId, T> restoring = new HashMap<>();
private final Set<TopicPartition> restoredPartitions = new HashSet<>();
private final Set<TaskId> previousActiveTasks = new HashSet<>();
// IQ may access this map.
Map<TaskId, T> running = new ConcurrentHashMap<>();
private Map<TopicPartition, T> runningByPartition = new HashMap<>();
Map<TopicPartition, T> restoringByPartition = new HashMap<>();
final Map<TaskId, T> running = new ConcurrentHashMap<>();
private final Map<TopicPartition, T> runningByPartition = new HashMap<>();
final Map<TopicPartition, T> restoringByPartition = new HashMap<>();

AssignedTasks(final LogContext logContext,
final String taskTypeName) {
Expand Down Expand Up @@ -176,7 +176,7 @@ private RuntimeException closeNonRunningTasks(final Collection<T> tasks) {

private RuntimeException suspendTasks(final Collection<T> tasks) {
final AtomicReference<RuntimeException> firstException = new AtomicReference<>(null);
for (Iterator<T> it = tasks.iterator(); it.hasNext(); ) {
for (final Iterator<T> it = tasks.iterator(); it.hasNext(); ) {
final T task = it.next();
try {
task.suspend();
Expand Down Expand Up @@ -249,10 +249,10 @@ boolean maybeResumeSuspendedTask(final TaskId taskId, final Set<TopicPartition>

private void addToRestoring(final T task) {
restoring.put(task.id(), task);
for (TopicPartition topicPartition : task.partitions()) {
for (final TopicPartition topicPartition : task.partitions()) {
restoringByPartition.put(topicPartition, task);
}
for (TopicPartition topicPartition : task.changelogPartitions()) {
for (final TopicPartition topicPartition : task.changelogPartitions()) {
restoringByPartition.put(topicPartition, task);
}
}
Expand All @@ -264,10 +264,10 @@ private void transitionToRunning(final T task) {
log.debug("transitioning {} {} to running", taskTypeName, task.id());
running.put(task.id(), task);
task.initializeTopology();
for (TopicPartition topicPartition : task.partitions()) {
for (final TopicPartition topicPartition : task.partitions()) {
runningByPartition.put(topicPartition, task);
}
for (TopicPartition topicPartition : task.changelogPartitions()) {
for (final TopicPartition topicPartition : task.changelogPartitions()) {
runningByPartition.put(topicPartition, task);
}
}
Expand Down Expand Up @@ -356,7 +356,7 @@ int commit() {
void applyToRunningTasks(final TaskAction<T> action) {
RuntimeException firstException = null;

for (Iterator<T> it = running().iterator(); it.hasNext(); ) {
for (final Iterator<T> it = running().iterator(); it.hasNext(); ) {
final T task = it.next();
try {
action.apply(task);
Expand Down
36 changes: 28 additions & 8 deletions streams/src/main/java/org/apache/kafka/streams/processor/internals/StreamThread.java
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Original file line number Diff line number Diff line change
Expand Up @@ -62,14 +62,15 @@
import java.util.Set;
import java.util.UUID;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicInteger;

import static java.util.Collections.singleton;

public class StreamThread extends Thread {

private final static int UNLIMITED_RECORDS = -1;
private static final AtomicInteger STREAM_THREAD_ID_SEQUENCE = new AtomicInteger(1);
private final static AtomicInteger STREAM_THREAD_ID_SEQUENCE = new AtomicInteger(1);

/**
* Stream thread states are the possible states that a stream thread can be in.
Expand Down Expand Up @@ -264,7 +265,9 @@ public void onPartitionsAssigned(final Collection<TopicPartition> assignment) {
if (streamThread.setState(State.PARTITIONS_ASSIGNED) == null) {
return;
}
taskManager.createTasks(assignment);
if (!streamThread.versionProbingFlag.get()) {
taskManager.createTasks(assignment);
}
} catch (final Throwable t) {
log.error(
"Error caught during partition assignment, " +
Expand Down Expand Up @@ -298,7 +301,11 @@ public void onPartitionsRevoked(final Collection<TopicPartition> assignment) {
final long start = time.milliseconds();
try {
// suspend active tasks
taskManager.suspendTasksAndState();
if (streamThread.versionProbingFlag.get()) {
streamThread.versionProbingFlag.set(false);
} else {
taskManager.suspendTasksAndState();
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I'm probably missing something and brought this up before, but above in onPartitionsAssigned we create tasks with the assignment when not version probing. But in onPartitionsRevoked if we are version probing we flip the version probing flag, hence on assignment we create tasks. Why don't we flip the version probing flag in onPartitionedAssigned as an else statement on line 270 so we are only every suspending and creating tasks during non-version probing rebalances?

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onPartitionsAssigned: if version probing flag is set, it means assignment is empty and we want to trigger a new rebalance. If we call taskManager.createTasks(assignment);, we would close suspended task and that is what we do not want to do at this point, because we hope to get those task assigned after the second rebalance.

onPartitionsRevoked: if version probing flag is set, we don't want to suspend tasks either. Tasks are already suspended but if we call taskManager.suspendTasksAndState(); again, we loose the information about currently suspended tasks (but we need to keep this information; ie, we avoid an incorrect internal metadata update here).

The flow is the following:

  • trigger first rebalance
  • onPartitionsRevoke -> version probing flag not set: suspend tasks regularly
  • onPartitionAssigned -> version probing flag set by StreamsPartitionsAssignor: we skip task creation as we will rebalance again (we cannot reset the flag here, because we need it in the next step)
  • trigger second rebalance
  • onPartitionsRevoke -> version probing flag is still set; we can reset the flag and skip suspending tasks to preserve metadata
  • onPartitionAssigned -> version probing flag not set: we do regular assignment and start processing

Does this make sense?

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yep - thanks for the clarification

}
} catch (final Throwable t) {
log.error(
"Error caught during partition revocation, " +
Expand Down Expand Up @@ -555,6 +562,7 @@ static class StreamsMetricsThreadImpl extends StreamsMetricsImpl {
private final String logPrefix;
private final TaskManager taskManager;
private final StreamsMetricsThreadImpl streamsMetrics;
private final AtomicBoolean versionProbingFlag;

private long lastCommitMs;
private long timerStartedMs;
Expand Down Expand Up @@ -647,6 +655,8 @@ public static StreamThread create(final InternalTopologyBuilder builder,
final String applicationId = config.getString(StreamsConfig.APPLICATION_ID_CONFIG);
final Map<String, Object> consumerConfigs = config.getMainConsumerConfigs(applicationId, threadClientId);
consumerConfigs.put(StreamsConfig.InternalConfig.TASK_MANAGER_FOR_PARTITION_ASSIGNOR, taskManager);
final AtomicBoolean versionProbingFlag = new AtomicBoolean();
consumerConfigs.put(StreamsConfig.InternalConfig.VERSION_PROBING_FLAG, versionProbingFlag);
String originalReset = null;
if (!builder.latestResetTopicsPattern().pattern().equals("") || !builder.earliestResetTopicsPattern().pattern().equals("")) {
originalReset = (String) consumerConfigs.get(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG);
Expand All @@ -666,7 +676,8 @@ public static StreamThread create(final InternalTopologyBuilder builder,
streamsMetrics,
builder,
threadClientId,
logContext);
logContext,
versionProbingFlag);
}

public StreamThread(final Time time,
Expand All @@ -679,7 +690,8 @@ public StreamThread(final Time time,
final StreamsMetricsThreadImpl streamsMetrics,
final InternalTopologyBuilder builder,
final String threadClientId,
final LogContext logContext) {
final LogContext logContext,
final AtomicBoolean versionProbingFlag) {
super(threadClientId);

this.stateLock = new Object();
Expand All @@ -696,6 +708,7 @@ public StreamThread(final Time time,
this.restoreConsumer = restoreConsumer;
this.consumer = consumer;
this.originalReset = originalReset;
this.versionProbingFlag = versionProbingFlag;

this.pollTimeMs = config.getLong(StreamsConfig.POLL_MS_CONFIG);
this.commitTimeMs = config.getLong(StreamsConfig.COMMIT_INTERVAL_MS_CONFIG);
Expand Down Expand Up @@ -750,19 +763,26 @@ private void runLoop() {
while (isRunning()) {
try {
recordsProcessedBeforeCommit = runOnce(recordsProcessedBeforeCommit);
if (versionProbingFlag.get()) {
log.info("Version probing detected. Triggering new rebalance.");
enforceRebalance();
}
} catch (final TaskMigratedException ignoreAndRejoinGroup) {
log.warn("Detected task {} that got migrated to another thread. " +
"This implies that this thread missed a rebalance and dropped out of the consumer group. " +
"Will try to rejoin the consumer group. Below is the detailed description of the task:\n{}",
ignoreAndRejoinGroup.migratedTask().id(), ignoreAndRejoinGroup.migratedTask().toString(">"));

// re-subscribe to enforce a rebalance in the next poll call
consumer.unsubscribe();
consumer.subscribe(builder.sourceTopicPattern(), rebalanceListener);
enforceRebalance();
}
}
}

private void enforceRebalance() {
consumer.unsubscribe();
consumer.subscribe(builder.sourceTopicPattern(), rebalanceListener);
}

/**
* @throws IllegalStateException If store gets registered after initialized is already finished
* @throws StreamsException If the store's change log does not contain the partition
Expand Down