somandal commented on code in PR #16857:
URL: https://github.com/apache/pinot/pull/16857#discussion_r2412042193
##########
pinot-controller/src/main/java/org/apache/pinot/controller/helix/core/minion/PinotTaskManager.java:
##########
@@ -239,40 +254,79 @@ public Map<String, String> createTask(String taskType,
String tableName, @Nullab
// Example usage in BaseTaskGenerator.getNumSubTasks()
taskConfigs.put(MinionConstants.TRIGGERED_BY,
CommonConstants.TaskTriggers.ADHOC_TRIGGER.name());
- List<PinotTaskConfig> pinotTaskConfigs =
taskGenerator.generateTasks(tableConfig, taskConfigs);
- if (pinotTaskConfigs.isEmpty()) {
- LOGGER.warn("No ad-hoc task generated for task type: {}", taskType);
- continue;
+ // Acquire distributed lock before proceeding with ad-hoc task generation
+ // Need locking to protect against:
+ // 1. Race conditions with periodic task generation
+ // 2. Multiple simultaneous ad-hoc requests
+ // 3. Leadership changes during task generation
+ DistributedTaskLockManager.TaskLock lock = null;
+ boolean taskCreationSuccess = true;
+ if (_distributedTaskLockManager != null) {
+ lock = _distributedTaskLockManager.acquireLock(tableNameWithType);
+ if (lock == null) {
+ String message = String.format("Could not acquire table level
distributed lock for ad-hoc task type: %s, "
+ + "table: %s. Another controller is likely generating tasks
for this type. Please try again later.",
+ taskType, tableNameWithType);
+ LOGGER.warn(message);
+ throw new RuntimeException(message);
+ }
+ LOGGER.info("Acquired table level distributed lock for ad-hoc task
type: {} on table: {}", taskType,
+ tableNameWithType);
}
- int maxNumberOfSubTasks = taskGenerator.getMaxAllowedSubTasksPerTask();
- if (pinotTaskConfigs.size() > maxNumberOfSubTasks) {
- String message = String.format(
- "Number of tasks generated for task type: %s for table: %s is %d,
which is greater than the "
- + "maximum number of tasks to schedule: %d. This is "
- + "controlled by the cluster config %s which is set based on
controller's performance.", taskType,
- tableName, pinotTaskConfigs.size(), maxNumberOfSubTasks,
MinionConstants.MAX_ALLOWED_SUB_TASKS_KEY);
- message += "Optimise the task config or reduce tableMaxNumTasks to
avoid the error";
- // We throw an exception to notify the user
- // This is to ensure that the user is aware of the task generation
limit
- throw new RuntimeException(message);
+
+ try {
+ List<PinotTaskConfig> pinotTaskConfigs =
taskGenerator.generateTasks(tableConfig, taskConfigs);
+ if (pinotTaskConfigs.isEmpty()) {
+ LOGGER.warn("No ad-hoc task generated for task type: {}, for table:
{}", taskType, tableNameWithType);
+ continue;
+ }
+ int maxNumberOfSubTasks = taskGenerator.getMaxAllowedSubTasksPerTask();
+ if (pinotTaskConfigs.size() > maxNumberOfSubTasks) {
+ String message = String.format(
+ "Number of tasks generated for task type: %s for table: %s is
%d, which is greater than the "
+ + "maximum number of tasks to schedule: %d. This is
controlled by the cluster config %s which is set "
+ + "based on controller's performance.", taskType,
tableNameWithType, pinotTaskConfigs.size(),
+ maxNumberOfSubTasks, MinionConstants.MAX_ALLOWED_SUB_TASKS_KEY);
+ message += "Optimise the task config or reduce tableMaxNumTasks to
avoid the error";
+ // We throw an exception to notify the user
+ // This is to ensure that the user is aware of the task generation
limit
+ taskCreationSuccess = false;
+ throw new RuntimeException(message);
+ }
+ pinotTaskConfigs.forEach(pinotTaskConfig ->
pinotTaskConfig.getConfigs()
+ .computeIfAbsent(MinionConstants.TRIGGERED_BY, k ->
CommonConstants.TaskTriggers.ADHOC_TRIGGER.name()));
+ addDefaultsToTaskConfig(pinotTaskConfigs);
+ LOGGER.info("Submitting ad-hoc task for task type: {} with task
configs: {}", taskType, pinotTaskConfigs);
+ _controllerMetrics.addMeteredTableValue(taskType,
ControllerMeter.NUMBER_ADHOC_TASKS_SUBMITTED, 1);
+ responseMap.put(tableNameWithType,
+ _helixTaskResourceManager.submitTask(parentTaskName,
pinotTaskConfigs, minionInstanceTag,
+ taskGenerator.getTaskTimeoutMs(minionInstanceTag),
+
taskGenerator.getNumConcurrentTasksPerInstance(minionInstanceTag),
+ taskGenerator.getMaxAttemptsPerTask(minionInstanceTag)));
+ } finally {
+ if (!responseMap.containsKey(tableNameWithType)) {
+ LOGGER.warn("No task submitted for tableNameWithType: {}",
tableNameWithType);
+ taskCreationSuccess = false;
+ }
+ if (lock != null) {
+ _distributedTaskLockManager.releaseLock(lock, taskCreationSuccess);
Review Comment:
removed this - was an artifact of the earlier -State node
##########
pinot-controller/src/main/java/org/apache/pinot/controller/helix/core/minion/DistributedTaskLockManager.java:
##########
@@ -0,0 +1,423 @@
+/**
+ * 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.pinot.controller.helix.core.minion;
+
+import com.google.common.annotations.VisibleForTesting;
+import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.List;
+import java.util.UUID;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+import javax.annotation.Nullable;
+import org.apache.helix.AccessOption;
+import org.apache.helix.store.zk.ZkHelixPropertyStore;
+import org.apache.helix.zookeeper.datamodel.ZNRecord;
+import org.apache.pinot.common.metadata.ZKMetadataProvider;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+
+/**
+ * Manages distributed locks for minion task generation using ZooKeeper
ephemeral sequential nodes.
+ * Uses ephemeral nodes that automatically disappear when the controller
session ends.
+ * This approach provides automatic cleanup and is suitable for long-running
task generation.
+ * Locks are held until explicitly released or the controller session
terminates.
+ * Locks are at the table level, to ensure that only one type of task can be
generated per table at any given time.
+ * <p>
+ * ZK EPHEMERAL_SEQUENTIAL Locks (see <a
href="https://zookeeper.apache.org/doc/current/recipes.html#sc_recipes_Locks";>
+ * ZooKeeper Lock Recipe.</a> for more details):
+ * <ul>
+ * <li>Every lock is created with a lock prefix. Lock prefix used:
[controllerName]-lock-[UUID]. The UUID helps
+ * differentiate between requests originating from the same controller at
the same time
+ * <li>When ZK creates the ZNode, it appends a sequence number at the end.
E.g.
+ * [controllerName]-lock-[UUID]-00000001
+ * <li>The sequence number is used to identify the lock winner in case
more than one lock node is created at the
+ * same time. The smallest sequence number always wins
+ * <li>The locks are EPHEMERAL in nature, meaning that once the session
with ZK is lost, the lock is automatically
+ * cleaned up. Scenarios when the ZK session can be lost: a) controller
shutdown, b) controller crash, c) ZK session
+ * expiry (e.g. long GC pauses can cause this)
+ * <li>This implementation does not set up watches as described in the
recipe as the task lock is released whenever
+ * we identify that the lock is already acquired. Do not expect lock
ownership to automatically change for the
+ * time being. If such support is needed in the future, this can be
enhanced to add a watch on the neighboring
+ * lock node
+ * </ul>
+ * <p>
+ * Example of how the locks will work:
+ * <p>
+ * Say we have two controllers, and one controller happens to run 2 threads at
the same time, all of which need to take
+ * the distributed lock. Each thread will create a distributed lock node, and
the "-Lock" ZNode getChildren will return:
+ * <ul>
+ * <li>controller2-lock-xyzwx-00000002
+ * <li>controller1-lock-abcde-00000001
+ * <li>controller1-lock-ab345-00000003
+ * </ul>
+ * <p>
+ * In the above, the controller1 with UUID abcde will win the lock as it has
the smallest sequence number. The other
+ * two threads will clean up their locks and return error that the distributed
lock could not be acquired. Controller1
+ * will proceed with performing its tasks, and when done will release the lock.
+ */
+public class DistributedTaskLockManager {
+ private static final Logger LOGGER =
LoggerFactory.getLogger(DistributedTaskLockManager.class);
+
+ // Lock paths are constructed using ZKMetadataProvider
+ private static final String LOCK_OWNER_KEY = "lockOwner";
+ private static final String LOCK_UUID_KEY = "lockUuid";
+ private static final String LOCK_TIMESTAMP_MILLIS_KEY =
"lockTimestampMillis";
+
+ // Define a custom comparator to compare strings of format
'<controllerName>-lock-<uuid>-<sequenceNumber>' and sort
+ // them by the sequence number at the end
+ private static final Comparator<String> TASK_LOCK_SEQUENCE_ID_COMPARATOR =
(s1, s2) -> {
+ // Regex to find the trailing sequence of digits
+ Pattern p = Pattern.compile("\\d+$");
+
+ // Extract the number from the first string
+ Matcher m1 = p.matcher(s1);
+ long num1 = m1.find() ? Long.parseLong(m1.group()) : 0;
+
+ // Extract the number from the second string
+ Matcher m2 = p.matcher(s2);
+ long num2 = m2.find() ? Long.parseLong(m2.group()) : 0;
+
+ return Long.compare(num1, num2);
+ };
+
+ private final ZkHelixPropertyStore<ZNRecord> _propertyStore;
+ private final String _controllerInstanceId;
+
+ public DistributedTaskLockManager(ZkHelixPropertyStore<ZNRecord>
propertyStore, String controllerInstanceId) {
+ _propertyStore = propertyStore;
+ _controllerInstanceId = controllerInstanceId;
+
+ // Ensure base paths exist
+ ensureBasePaths();
+ }
+
+ /**
+ * Attempts to acquire a distributed lock at the table level for task
generation using session-based locking.
+ * The lock is held until explicitly released or the controller session ends.
Review Comment:
done
##########
pinot-controller/src/main/java/org/apache/pinot/controller/helix/core/minion/PinotTaskManager.java:
##########
@@ -210,6 +224,7 @@ public Map<String, String> createTask(String taskType,
String tableName, @Nullab
if (tableNameWithTypes.isEmpty()) {
throw new TableNotFoundException("'tableName' " + tableName + " is not
found");
}
+ LOGGER.info("Generating tasks for {} tables, list: {}",
tableNameWithTypes.size(), tableNameWithTypes);
Review Comment:
done
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