guozhangwang commented on code in PR #12044:
URL: https://github.com/apache/kafka/pull/12044#discussion_r850797609
##########
clients/src/test/java/org/apache/kafka/common/utils/ExponentialBackoffTest.java:
##########
@@ -20,30 +20,42 @@
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertTrue;
public class ExponentialBackoffTest {
@Test
public void testExponentialBackoff() {
- long scaleFactor = 100;
+ long scaleFactor = 3000;
int ratio = 2;
- long backoffMax = 2000;
- double jitter = 0.2;
+ long backoffMax = 60 * 1000;
+ double jitter = 0.02;
ExponentialBackoff exponentialBackoff = new ExponentialBackoff(
scaleFactor, ratio, backoffMax, jitter
);
- for (int i = 0; i <= 100; i++) {
- for (int attempts = 0; attempts <= 10; attempts++) {
- if (attempts <= 4) {
- assertEquals(scaleFactor * Math.pow(ratio, attempts),
- exponentialBackoff.backoff(attempts),
- scaleFactor * Math.pow(ratio, attempts) * jitter);
- } else {
- assertTrue(exponentialBackoff.backoff(attempts) <=
backoffMax * (1 + jitter));
- }
- }
- }
+
+ int numAttempts = 0;
+ System.out.println(String.format("backoff with num attempts = %s is
%s", numAttempts, exponentialBackoff.backoff(numAttempts)));
Review Comment:
Is this println intentional? Also we seems do not have any assertions
anymore.
##########
streams/src/main/java/org/apache/kafka/streams/processor/internals/TaskScheduler.java:
##########
@@ -0,0 +1,161 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.kafka.streams.processor.internals;
+
+import org.apache.kafka.common.utils.ExponentialBackoff;
+import org.apache.kafka.common.utils.LogContext;
+import org.apache.kafka.streams.processor.TaskId;
+
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+import org.slf4j.Logger;
+
+import static
org.apache.kafka.streams.processor.internals.TopologyMetadata.UNNAMED_TOPOLOGY;
+
+/**
+ * Multi-threaded class that tracks the status of active tasks being processed
and decides if/when they can
+ * be executed.
+ *
+ * Note: A single instance of this class is shared between all StreamThreads,
so it must be thread-safe
+ */
+public class TaskScheduler {
+ // Reaches the maximum backoff interval in about 5 attempts, at which point
+ private static final long INITIAL_BACKOFF_MS = 3 * 1000L; // wait 3s
after the first task failure
+ private static final int RETRY_BACKOFF_EXP_BASE = 2;
+ private static final long MAXIMUM_BACKOFF_MS = 60 * 1000L; // back off up
to a maximum of 1 minute between retries
+ private static final double RETRY_BACKOFF_JITTER = 0.02;
+
+ // Once an individual task has been failing consistently for the past 30s
or more, we "extend" the backoff to all
+ // other tasks in that topology, to avoid letting different subtopologies
become too far out of sync and potentially
+ // missing for example the output of a join where only one side is blocked
upstream due to task errors
+ private static final long EXTEND_TASK_BACKOFF_TO_FULL_TOPOLOGY_MS = 30 *
1000L;
+
+ enum TaskStatus {
+ RUNNING, // the task and its topology are healthy and able to be
processed
+ BACKOFF, // the task and/or its topology are unhealthy, task has
remaining backoff time to wait before a retry
+ RETRIABLE // the task and/or its topology are still considered
unhealthy but are ready to be retried
+ }
+
+ private final ExponentialBackoff taskBackoff = new ExponentialBackoff(
+ INITIAL_BACKOFF_MS,
+ RETRY_BACKOFF_EXP_BASE,
+ MAXIMUM_BACKOFF_MS,
+ RETRY_BACKOFF_JITTER
+ );
+
+ // map of topologies experiencing errors/currently under backoff
+ private final ConcurrentHashMap<String, NamedTopologyMetadata>
topologyNameToErrorMetadata = new ConcurrentHashMap<>();
+ private final boolean hasNamedTopologies;
+
+ public TaskScheduler(final Set<String> allTopologyNames) {
+ this.hasNamedTopologies = !(allTopologyNames.size() == 1 &&
allTopologyNames.contains(UNNAMED_TOPOLOGY));
+ }
+
+ public TaskStatus getTaskStatus(final Task task, final long now) {
+ final String topologyName = task.id().topologyName();
+ if (!hasNamedTopologies) {
+ // TODO implement error handling/backoff for non-named topologies
(needs KIP)
+ return TaskStatus.RUNNING;
+ } else {
+ final NamedTopologyMetadata metadata =
topologyNameToErrorMetadata.get(topologyName);
+ if (metadata == null) {
+ return TaskStatus.RUNNING;
+ } else {
+ return metadata.getTaskStatus(task, now);
+ }
+ }
+ }
+
+ public void registerTaskError(final Task task, final long now) {
+ if (hasNamedTopologies) {
+ final String topologyName = task.id().topologyName();
+ // Only need to register this error if the task is currently
healthy
+ if (!topologyNameToErrorMetadata.containsKey(topologyName)) {
+ final NamedTopologyMetadata namedTopologyMetadata = new
NamedTopologyMetadata(topologyName);
+ namedTopologyMetadata.registerTaskError(task, now);
+ topologyNameToErrorMetadata.put(topologyName,
namedTopologyMetadata);
+ }
+ }
+ }
+
+ public void registerTaskSuccess(final Task task) {
+ if (hasNamedTopologies && task.id().topologyName() != null) {
+ final NamedTopologyMetadata topologyMetadata =
topologyNameToErrorMetadata.get(task.id().topologyName());
+ if (topologyMetadata != null) {
+ topologyMetadata.registerRetrySuccess(task);
+ }
+ }
+ }
+
+ private class NamedTopologyMetadata {
+ private final Logger log;
+ private final Map<TaskId, ErrorMetadata> tasksToErrorTime = new
ConcurrentHashMap<>();
+
+ public NamedTopologyMetadata(final String topologyName) {
+ final LogContext logContext = new
LogContext(String.format("topology-name [%s] ", topologyName));
+ this.log = logContext.logger(NamedTopologyMetadata.class);
+ }
+
+ public TaskStatus getTaskStatus(final Task task, final long now) {
+ final ErrorMetadata errorMetadata =
tasksToErrorTime.get(task.id());
+ if (errorMetadata != null) {
+ ++errorMetadata.numAttempts;
+
+ final long remainingBackoffMs = now -
errorMetadata.firstErrorTimeMs + taskBackoff.backoff(errorMetadata.numAttempts);
Review Comment:
The logic here seems incorrect to me: the remaining backoff should be
```
taskBackoff.backoff(errorMetadata.numAttempts) - (now -
errorMetadata.firstErrorTimeM)
= taskBackoff.backoff(errorMetadata.numAttempts) - now +
errorMetadata.firstErrorTimeM
```
right?
##########
streams/src/main/java/org/apache/kafka/streams/processor/internals/TaskScheduler.java:
##########
@@ -0,0 +1,161 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.kafka.streams.processor.internals;
+
+import org.apache.kafka.common.utils.ExponentialBackoff;
+import org.apache.kafka.common.utils.LogContext;
+import org.apache.kafka.streams.processor.TaskId;
+
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+import org.slf4j.Logger;
+
+import static
org.apache.kafka.streams.processor.internals.TopologyMetadata.UNNAMED_TOPOLOGY;
+
+/**
+ * Multi-threaded class that tracks the status of active tasks being processed
and decides if/when they can
+ * be executed.
+ *
+ * Note: A single instance of this class is shared between all StreamThreads,
so it must be thread-safe
+ */
+public class TaskScheduler {
+ // Reaches the maximum backoff interval in about 5 attempts, at which point
+ private static final long INITIAL_BACKOFF_MS = 3 * 1000L; // wait 3s
after the first task failure
+ private static final int RETRY_BACKOFF_EXP_BASE = 2;
+ private static final long MAXIMUM_BACKOFF_MS = 60 * 1000L; // back off up
to a maximum of 1 minute between retries
+ private static final double RETRY_BACKOFF_JITTER = 0.02;
+
+ // Once an individual task has been failing consistently for the past 30s
or more, we "extend" the backoff to all
+ // other tasks in that topology, to avoid letting different subtopologies
become too far out of sync and potentially
+ // missing for example the output of a join where only one side is blocked
upstream due to task errors
+ private static final long EXTEND_TASK_BACKOFF_TO_FULL_TOPOLOGY_MS = 30 *
1000L;
+
+ enum TaskStatus {
+ RUNNING, // the task and its topology are healthy and able to be
processed
+ BACKOFF, // the task and/or its topology are unhealthy, task has
remaining backoff time to wait before a retry
+ RETRIABLE // the task and/or its topology are still considered
unhealthy but are ready to be retried
+ }
+
+ private final ExponentialBackoff taskBackoff = new ExponentialBackoff(
+ INITIAL_BACKOFF_MS,
+ RETRY_BACKOFF_EXP_BASE,
+ MAXIMUM_BACKOFF_MS,
+ RETRY_BACKOFF_JITTER
+ );
+
+ // map of topologies experiencing errors/currently under backoff
+ private final ConcurrentHashMap<String, NamedTopologyMetadata>
topologyNameToErrorMetadata = new ConcurrentHashMap<>();
+ private final boolean hasNamedTopologies;
+
+ public TaskScheduler(final Set<String> allTopologyNames) {
+ this.hasNamedTopologies = !(allTopologyNames.size() == 1 &&
allTopologyNames.contains(UNNAMED_TOPOLOGY));
+ }
+
+ public TaskStatus getTaskStatus(final Task task, final long now) {
+ final String topologyName = task.id().topologyName();
+ if (!hasNamedTopologies) {
+ // TODO implement error handling/backoff for non-named topologies
(needs KIP)
+ return TaskStatus.RUNNING;
+ } else {
+ final NamedTopologyMetadata metadata =
topologyNameToErrorMetadata.get(topologyName);
+ if (metadata == null) {
+ return TaskStatus.RUNNING;
+ } else {
+ return metadata.getTaskStatus(task, now);
+ }
+ }
+ }
+
+ public void registerTaskError(final Task task, final long now) {
+ if (hasNamedTopologies) {
+ final String topologyName = task.id().topologyName();
+ // Only need to register this error if the task is currently
healthy
+ if (!topologyNameToErrorMetadata.containsKey(topologyName)) {
+ final NamedTopologyMetadata namedTopologyMetadata = new
NamedTopologyMetadata(topologyName);
+ namedTopologyMetadata.registerTaskError(task, now);
+ topologyNameToErrorMetadata.put(topologyName,
namedTopologyMetadata);
+ }
+ }
+ }
+
+ public void registerTaskSuccess(final Task task) {
+ if (hasNamedTopologies && task.id().topologyName() != null) {
+ final NamedTopologyMetadata topologyMetadata =
topologyNameToErrorMetadata.get(task.id().topologyName());
+ if (topologyMetadata != null) {
+ topologyMetadata.registerRetrySuccess(task);
+ }
+ }
+ }
+
+ private class NamedTopologyMetadata {
+ private final Logger log;
+ private final Map<TaskId, ErrorMetadata> tasksToErrorTime = new
ConcurrentHashMap<>();
+
+ public NamedTopologyMetadata(final String topologyName) {
+ final LogContext logContext = new
LogContext(String.format("topology-name [%s] ", topologyName));
+ this.log = logContext.logger(NamedTopologyMetadata.class);
+ }
+
+ public TaskStatus getTaskStatus(final Task task, final long now) {
+ final ErrorMetadata errorMetadata =
tasksToErrorTime.get(task.id());
+ if (errorMetadata != null) {
+ ++errorMetadata.numAttempts;
+
+ final long remainingBackoffMs = now -
errorMetadata.firstErrorTimeMs + taskBackoff.backoff(errorMetadata.numAttempts);
+
+ if (remainingBackoffMs > 0) {
Review Comment:
If my previous comment is reasonable, this should be `remainingBackoffMs <=
0` right?
##########
streams/src/main/java/org/apache/kafka/streams/processor/internals/TopologyMetadata.java:
##########
@@ -166,8 +166,8 @@ public void unregisterThread(final String threadName) {
maybeNotifyTopologyVersionListeners();
}
- public TaskExecutionMetadata taskExecutionMetadata() {
- return taskExecutionMetadata;
+ public TaskScheduler taskExecutionMetadata() {
Review Comment:
nit: rename the function too?
##########
streams/src/main/java/org/apache/kafka/streams/processor/internals/TaskScheduler.java:
##########
@@ -0,0 +1,161 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.kafka.streams.processor.internals;
+
+import org.apache.kafka.common.utils.ExponentialBackoff;
+import org.apache.kafka.common.utils.LogContext;
+import org.apache.kafka.streams.processor.TaskId;
+
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+import org.slf4j.Logger;
+
+import static
org.apache.kafka.streams.processor.internals.TopologyMetadata.UNNAMED_TOPOLOGY;
+
+/**
+ * Multi-threaded class that tracks the status of active tasks being processed
and decides if/when they can
+ * be executed.
+ *
+ * Note: A single instance of this class is shared between all StreamThreads,
so it must be thread-safe
+ */
+public class TaskScheduler {
+ // Reaches the maximum backoff interval in about 5 attempts, at which point
+ private static final long INITIAL_BACKOFF_MS = 3 * 1000L; // wait 3s
after the first task failure
+ private static final int RETRY_BACKOFF_EXP_BASE = 2;
+ private static final long MAXIMUM_BACKOFF_MS = 60 * 1000L; // back off up
to a maximum of 1 minute between retries
+ private static final double RETRY_BACKOFF_JITTER = 0.02;
+
+ // Once an individual task has been failing consistently for the past 30s
or more, we "extend" the backoff to all
+ // other tasks in that topology, to avoid letting different subtopologies
become too far out of sync and potentially
+ // missing for example the output of a join where only one side is blocked
upstream due to task errors
+ private static final long EXTEND_TASK_BACKOFF_TO_FULL_TOPOLOGY_MS = 30 *
1000L;
+
+ enum TaskStatus {
+ RUNNING, // the task and its topology are healthy and able to be
processed
+ BACKOFF, // the task and/or its topology are unhealthy, task has
remaining backoff time to wait before a retry
+ RETRIABLE // the task and/or its topology are still considered
unhealthy but are ready to be retried
+ }
+
+ private final ExponentialBackoff taskBackoff = new ExponentialBackoff(
+ INITIAL_BACKOFF_MS,
+ RETRY_BACKOFF_EXP_BASE,
+ MAXIMUM_BACKOFF_MS,
+ RETRY_BACKOFF_JITTER
+ );
+
+ // map of topologies experiencing errors/currently under backoff
+ private final ConcurrentHashMap<String, NamedTopologyMetadata>
topologyNameToErrorMetadata = new ConcurrentHashMap<>();
+ private final boolean hasNamedTopologies;
+
+ public TaskScheduler(final Set<String> allTopologyNames) {
+ this.hasNamedTopologies = !(allTopologyNames.size() == 1 &&
allTopologyNames.contains(UNNAMED_TOPOLOGY));
+ }
+
+ public TaskStatus getTaskStatus(final Task task, final long now) {
+ final String topologyName = task.id().topologyName();
+ if (!hasNamedTopologies) {
+ // TODO implement error handling/backoff for non-named topologies
(needs KIP)
+ return TaskStatus.RUNNING;
+ } else {
+ final NamedTopologyMetadata metadata =
topologyNameToErrorMetadata.get(topologyName);
+ if (metadata == null) {
+ return TaskStatus.RUNNING;
+ } else {
+ return metadata.getTaskStatus(task, now);
+ }
+ }
+ }
+
+ public void registerTaskError(final Task task, final long now) {
+ if (hasNamedTopologies) {
+ final String topologyName = task.id().topologyName();
+ // Only need to register this error if the task is currently
healthy
+ if (!topologyNameToErrorMetadata.containsKey(topologyName)) {
+ final NamedTopologyMetadata namedTopologyMetadata = new
NamedTopologyMetadata(topologyName);
+ namedTopologyMetadata.registerTaskError(task, now);
+ topologyNameToErrorMetadata.put(topologyName,
namedTopologyMetadata);
+ }
+ }
+ }
+
+ public void registerTaskSuccess(final Task task) {
+ if (hasNamedTopologies && task.id().topologyName() != null) {
+ final NamedTopologyMetadata topologyMetadata =
topologyNameToErrorMetadata.get(task.id().topologyName());
+ if (topologyMetadata != null) {
+ topologyMetadata.registerRetrySuccess(task);
+ }
+ }
+ }
+
+ private class NamedTopologyMetadata {
+ private final Logger log;
+ private final Map<TaskId, ErrorMetadata> tasksToErrorTime = new
ConcurrentHashMap<>();
+
+ public NamedTopologyMetadata(final String topologyName) {
+ final LogContext logContext = new
LogContext(String.format("topology-name [%s] ", topologyName));
+ this.log = logContext.logger(NamedTopologyMetadata.class);
+ }
+
+ public TaskStatus getTaskStatus(final Task task, final long now) {
+ final ErrorMetadata errorMetadata =
tasksToErrorTime.get(task.id());
+ if (errorMetadata != null) {
+ ++errorMetadata.numAttempts;
+
+ final long remainingBackoffMs = now -
errorMetadata.firstErrorTimeMs + taskBackoff.backoff(errorMetadata.numAttempts);
+
+ if (remainingBackoffMs > 0) {
+ log.info("Task {} is ready to re-attempt processing, retry
attempt count is {}",
+ task.id(), errorMetadata.numAttempts);
+ return TaskStatus.RETRIABLE;
+ } else {
+ log.debug("Skip processing for task {} with remaining
backoff time = {}ms",
+ task.id(), remainingBackoffMs);
+ return TaskStatus.BACKOFF;
+ }
+ } else {
+ // TODO: implement full backoff for unhealthy topologies with
high-frequency task errors
+
+ return TaskStatus.RUNNING;
+ }
+ }
+
+ public synchronized void registerTaskError(final Task task, final long
now) {
Review Comment:
Why these two functions are synchronized but not `getTaskStatus` above? I
feel the `synchronized` here and below are not necessary.
##########
streams/src/main/java/org/apache/kafka/streams/processor/internals/TaskScheduler.java:
##########
@@ -0,0 +1,161 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.kafka.streams.processor.internals;
+
+import org.apache.kafka.common.utils.ExponentialBackoff;
+import org.apache.kafka.common.utils.LogContext;
+import org.apache.kafka.streams.processor.TaskId;
+
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+import org.slf4j.Logger;
+
+import static
org.apache.kafka.streams.processor.internals.TopologyMetadata.UNNAMED_TOPOLOGY;
+
+/**
+ * Multi-threaded class that tracks the status of active tasks being processed
and decides if/when they can
+ * be executed.
+ *
+ * Note: A single instance of this class is shared between all StreamThreads,
so it must be thread-safe
+ */
+public class TaskScheduler {
+ // Reaches the maximum backoff interval in about 5 attempts, at which point
+ private static final long INITIAL_BACKOFF_MS = 3 * 1000L; // wait 3s
after the first task failure
+ private static final int RETRY_BACKOFF_EXP_BASE = 2;
+ private static final long MAXIMUM_BACKOFF_MS = 60 * 1000L; // back off up
to a maximum of 1 minute between retries
+ private static final double RETRY_BACKOFF_JITTER = 0.02;
+
+ // Once an individual task has been failing consistently for the past 30s
or more, we "extend" the backoff to all
+ // other tasks in that topology, to avoid letting different subtopologies
become too far out of sync and potentially
+ // missing for example the output of a join where only one side is blocked
upstream due to task errors
+ private static final long EXTEND_TASK_BACKOFF_TO_FULL_TOPOLOGY_MS = 30 *
1000L;
+
+ enum TaskStatus {
+ RUNNING, // the task and its topology are healthy and able to be
processed
+ BACKOFF, // the task and/or its topology are unhealthy, task has
remaining backoff time to wait before a retry
+ RETRIABLE // the task and/or its topology are still considered
unhealthy but are ready to be retried
+ }
+
+ private final ExponentialBackoff taskBackoff = new ExponentialBackoff(
+ INITIAL_BACKOFF_MS,
+ RETRY_BACKOFF_EXP_BASE,
+ MAXIMUM_BACKOFF_MS,
+ RETRY_BACKOFF_JITTER
+ );
+
+ // map of topologies experiencing errors/currently under backoff
+ private final ConcurrentHashMap<String, NamedTopologyMetadata>
topologyNameToErrorMetadata = new ConcurrentHashMap<>();
+ private final boolean hasNamedTopologies;
+
+ public TaskScheduler(final Set<String> allTopologyNames) {
+ this.hasNamedTopologies = !(allTopologyNames.size() == 1 &&
allTopologyNames.contains(UNNAMED_TOPOLOGY));
+ }
+
+ public TaskStatus getTaskStatus(final Task task, final long now) {
+ final String topologyName = task.id().topologyName();
+ if (!hasNamedTopologies) {
+ // TODO implement error handling/backoff for non-named topologies
(needs KIP)
+ return TaskStatus.RUNNING;
+ } else {
+ final NamedTopologyMetadata metadata =
topologyNameToErrorMetadata.get(topologyName);
+ if (metadata == null) {
+ return TaskStatus.RUNNING;
+ } else {
+ return metadata.getTaskStatus(task, now);
+ }
+ }
+ }
+
+ public void registerTaskError(final Task task, final long now) {
+ if (hasNamedTopologies) {
+ final String topologyName = task.id().topologyName();
+ // Only need to register this error if the task is currently
healthy
+ if (!topologyNameToErrorMetadata.containsKey(topologyName)) {
+ final NamedTopologyMetadata namedTopologyMetadata = new
NamedTopologyMetadata(topologyName);
+ namedTopologyMetadata.registerTaskError(task, now);
+ topologyNameToErrorMetadata.put(topologyName,
namedTopologyMetadata);
+ }
+ }
+ }
+
+ public void registerTaskSuccess(final Task task) {
+ if (hasNamedTopologies && task.id().topologyName() != null) {
+ final NamedTopologyMetadata topologyMetadata =
topologyNameToErrorMetadata.get(task.id().topologyName());
+ if (topologyMetadata != null) {
+ topologyMetadata.registerRetrySuccess(task);
+ }
+ }
+ }
+
+ private class NamedTopologyMetadata {
+ private final Logger log;
+ private final Map<TaskId, ErrorMetadata> tasksToErrorTime = new
ConcurrentHashMap<>();
+
+ public NamedTopologyMetadata(final String topologyName) {
+ final LogContext logContext = new
LogContext(String.format("topology-name [%s] ", topologyName));
+ this.log = logContext.logger(NamedTopologyMetadata.class);
+ }
+
+ public TaskStatus getTaskStatus(final Task task, final long now) {
+ final ErrorMetadata errorMetadata =
tasksToErrorTime.get(task.id());
+ if (errorMetadata != null) {
+ ++errorMetadata.numAttempts;
Review Comment:
I thought we would only increment `numAttempts` when we fail the task
(repeatedly), but not whenever we call `getTaskStatus`. Otherwise the backoff
would keep increasing as we call `getTaskStatus` repeatedly right?
##########
streams/src/main/java/org/apache/kafka/streams/processor/internals/TaskScheduler.java:
##########
@@ -0,0 +1,161 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.kafka.streams.processor.internals;
+
+import org.apache.kafka.common.utils.ExponentialBackoff;
+import org.apache.kafka.common.utils.LogContext;
+import org.apache.kafka.streams.processor.TaskId;
+
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+import org.slf4j.Logger;
+
+import static
org.apache.kafka.streams.processor.internals.TopologyMetadata.UNNAMED_TOPOLOGY;
+
+/**
+ * Multi-threaded class that tracks the status of active tasks being processed
and decides if/when they can
+ * be executed.
+ *
+ * Note: A single instance of this class is shared between all StreamThreads,
so it must be thread-safe
+ */
+public class TaskScheduler {
+ // Reaches the maximum backoff interval in about 5 attempts, at which point
+ private static final long INITIAL_BACKOFF_MS = 3 * 1000L; // wait 3s
after the first task failure
+ private static final int RETRY_BACKOFF_EXP_BASE = 2;
+ private static final long MAXIMUM_BACKOFF_MS = 60 * 1000L; // back off up
to a maximum of 1 minute between retries
+ private static final double RETRY_BACKOFF_JITTER = 0.02;
+
+ // Once an individual task has been failing consistently for the past 30s
or more, we "extend" the backoff to all
+ // other tasks in that topology, to avoid letting different subtopologies
become too far out of sync and potentially
+ // missing for example the output of a join where only one side is blocked
upstream due to task errors
+ private static final long EXTEND_TASK_BACKOFF_TO_FULL_TOPOLOGY_MS = 30 *
1000L;
+
+ enum TaskStatus {
+ RUNNING, // the task and its topology are healthy and able to be
processed
+ BACKOFF, // the task and/or its topology are unhealthy, task has
remaining backoff time to wait before a retry
+ RETRIABLE // the task and/or its topology are still considered
unhealthy but are ready to be retried
+ }
+
+ private final ExponentialBackoff taskBackoff = new ExponentialBackoff(
+ INITIAL_BACKOFF_MS,
+ RETRY_BACKOFF_EXP_BASE,
+ MAXIMUM_BACKOFF_MS,
+ RETRY_BACKOFF_JITTER
+ );
+
+ // map of topologies experiencing errors/currently under backoff
+ private final ConcurrentHashMap<String, NamedTopologyMetadata>
topologyNameToErrorMetadata = new ConcurrentHashMap<>();
+ private final boolean hasNamedTopologies;
+
+ public TaskScheduler(final Set<String> allTopologyNames) {
+ this.hasNamedTopologies = !(allTopologyNames.size() == 1 &&
allTopologyNames.contains(UNNAMED_TOPOLOGY));
+ }
+
+ public TaskStatus getTaskStatus(final Task task, final long now) {
+ final String topologyName = task.id().topologyName();
+ if (!hasNamedTopologies) {
+ // TODO implement error handling/backoff for non-named topologies
(needs KIP)
+ return TaskStatus.RUNNING;
+ } else {
+ final NamedTopologyMetadata metadata =
topologyNameToErrorMetadata.get(topologyName);
+ if (metadata == null) {
+ return TaskStatus.RUNNING;
+ } else {
+ return metadata.getTaskStatus(task, now);
+ }
+ }
+ }
+
+ public void registerTaskError(final Task task, final long now) {
+ if (hasNamedTopologies) {
+ final String topologyName = task.id().topologyName();
+ // Only need to register this error if the task is currently
healthy
+ if (!topologyNameToErrorMetadata.containsKey(topologyName)) {
+ final NamedTopologyMetadata namedTopologyMetadata = new
NamedTopologyMetadata(topologyName);
+ namedTopologyMetadata.registerTaskError(task, now);
+ topologyNameToErrorMetadata.put(topologyName,
namedTopologyMetadata);
+ }
+ }
+ }
+
+ public void registerTaskSuccess(final Task task) {
+ if (hasNamedTopologies && task.id().topologyName() != null) {
+ final NamedTopologyMetadata topologyMetadata =
topologyNameToErrorMetadata.get(task.id().topologyName());
+ if (topologyMetadata != null) {
+ topologyMetadata.registerRetrySuccess(task);
+ }
+ }
+ }
+
+ private class NamedTopologyMetadata {
+ private final Logger log;
+ private final Map<TaskId, ErrorMetadata> tasksToErrorTime = new
ConcurrentHashMap<>();
+
+ public NamedTopologyMetadata(final String topologyName) {
+ final LogContext logContext = new
LogContext(String.format("topology-name [%s] ", topologyName));
+ this.log = logContext.logger(NamedTopologyMetadata.class);
+ }
+
+ public TaskStatus getTaskStatus(final Task task, final long now) {
+ final ErrorMetadata errorMetadata =
tasksToErrorTime.get(task.id());
+ if (errorMetadata != null) {
+ ++errorMetadata.numAttempts;
+
+ final long remainingBackoffMs = now -
errorMetadata.firstErrorTimeMs + taskBackoff.backoff(errorMetadata.numAttempts);
+
+ if (remainingBackoffMs > 0) {
+ log.info("Task {} is ready to re-attempt processing, retry
attempt count is {}",
+ task.id(), errorMetadata.numAttempts);
+ return TaskStatus.RETRIABLE;
+ } else {
+ log.debug("Skip processing for task {} with remaining
backoff time = {}ms",
+ task.id(), remainingBackoffMs);
+ return TaskStatus.BACKOFF;
+ }
+ } else {
+ // TODO: implement full backoff for unhealthy topologies with
high-frequency task errors
Review Comment:
I'm not sure I follow this TODO here: why it's related to `if (errorMetadata
== null)` condition?
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