somandal commented on code in PR #16857:
URL: https://github.com/apache/pinot/pull/16857#discussion_r2414342812
##########
pinot-controller/src/main/java/org/apache/pinot/controller/helix/core/minion/PinotTaskManager.java:
##########
@@ -239,40 +254,76 @@ 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;
+ 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 table. 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
+ 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);
+ }
+ if (lock != null) {
+ _distributedTaskLockManager.releaseLock(lock);
+ }
}
- 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)));
}
if (responseMap.isEmpty()) {
LOGGER.warn("No task submitted for tableName: {}", tableName);
}
return responseMap;
}
+ public boolean forceReleaseLock(String tableNameWithType) {
+ if (_distributedTaskLockManager == null) {
+ LOGGER.info("Distributed task lock manager is disabled, no locks to
release");
Review Comment:
done
##########
pinot-controller/src/main/java/org/apache/pinot/controller/helix/core/minion/DistributedTaskLockManager.java:
##########
@@ -0,0 +1,288 @@
+/**
+ * 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.concurrent.TimeUnit;
+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.apache.pinot.common.metrics.ControllerMetrics;
+import org.apache.pinot.common.metrics.ControllerTimer;
+import org.apache.zookeeper.data.Stat;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+
+/**
+ * Manages distributed locks for minion task generation using ZooKeeper
ephemeral nodes that automatically disappear
+ * when the controller session ends or when the lock is explicitly released.
This approach provides automatic cleanup
+ * and is suitable for long-running task generation.
+ * Locks are at the table level, to ensure that only one type of task can be
generated per table at any given time.
+ * This is to prevent task types which shouldn't run in parallel from being
generated at the same time.
+ * <p>
+ * ZK EPHEMERAL Lock Node:
+ * <ul>
+ * <li>Every lock is created at the table level with the name:
{tableName}-Lock, under the base path
+ * MINION_TASK_METADATA within the PROPERTYSTORE.
+ * <li>If the propertyStore::create() call returns true, that means the
lock node was successfully created and the
+ * lock belongs to the current controller, otherwise it was not. If the
lock node already exists, this will return
+ * false. No clean-up of the lock node is needed if the
propertyStore::create() call returns false.
+ * <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). This property helps ensure
that the lock is released under
+ * controller failure.
+ * </ul>
+ * <p>
+ */
+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_CREATION_TIME_MS = "lockCreationTimeMs";
+
+ private final ZkHelixPropertyStore<ZNRecord> _propertyStore;
+ private final String _controllerInstanceId;
+ private final ControllerMetrics _controllerMetrics;
+
+ public DistributedTaskLockManager(ZkHelixPropertyStore<ZNRecord>
propertyStore, String controllerInstanceId) {
+ _propertyStore = propertyStore;
+ _controllerInstanceId = controllerInstanceId;
+ _controllerMetrics = ControllerMetrics.get();
+ }
+
+ /**
+ * Attempts to acquire a distributed lock at the table level for task
generation using session-based locking.
+ * The lock is at the table level instead of the task level to ensure that
only a single task can be generated for
+ * a given table at any time. Certain tasks depend on other tasks not being
generated at the same time
+ * The lock is held until explicitly released or the controller session ends.
+ *
+ * @param tableNameWithType the table name with type
+ * @return TaskLock object if successful, null if lock could not be acquired
+ */
+ @Nullable
+ public TaskLock acquireLock(String tableNameWithType) {
+ LOGGER.info("Attempting to acquire task generation lock for table: {} by
controller: {}", tableNameWithType,
+ _controllerInstanceId);
+
+ try {
+ // Check if task generation is already in progress
+ if (isTaskGenerationInProgress(tableNameWithType)) {
+ LOGGER.info("Task generation already in progress for: {} by this or
another controller", tableNameWithType);
+ return null;
+ }
+
+ // Try to acquire the lock using ephemeral node
+ TaskLock lock = tryAcquireSessionBasedLock(tableNameWithType);
+ if (lock != null) {
+ LOGGER.info("Successfully acquired task generation lock for table: {}
by controller: {}", tableNameWithType,
+ _controllerInstanceId);
+ return lock;
+ } else {
+ LOGGER.warn("Could not acquire lock for table: {} - another controller
must hold it", tableNameWithType);
+ }
+ } catch (Exception e) {
+ LOGGER.error("Error while trying to acquire task lock for table: {}",
tableNameWithType, e);
+ }
+ return null;
+ }
+
+ private String getLockPath(String tableNameForPath) {
+ return
ZKMetadataProvider.constructPropertyStorePathForMinionTaskGenerationLock(tableNameForPath);
+ }
+
+ /**
+ * Releases a previously acquired session-based lock and marks task
generation as completed.
+ *
+ * @param lock the lock to release
+ * @return true if successfully released, false otherwise
+ */
+ public boolean releaseLock(TaskLock lock) {
+ if (lock == null) {
+ return true;
+ }
+
+ String tableNameWithType = lock.getTableNameWithType();
+ String lockNode = lock.getLockZNodePath();
+
+ // Remove the ephemeral lock node
+ boolean status = true;
+ if (lockNode != null) {
+ try {
+ if (_propertyStore.exists(lockNode, AccessOption.EPHEMERAL)) {
+ status = _propertyStore.remove(lockNode, AccessOption.EPHEMERAL);
+ LOGGER.info("Tried to removed ephemeral lock node: {}, for table: {}
by controller: {}, removal success: {}",
+ lockNode, tableNameWithType, _controllerInstanceId, status);
+ } else {
+ LOGGER.warn("Ephemeral lock node: {} does not exist for table: {},
nothing to remove",
+ lockNode, tableNameWithType);
+ }
+ } catch (Exception e) {
+ status = false;
+ LOGGER.warn("Exception while trying to remove ephemeral lock node:
{}", lockNode, e);
+ }
+ } else {
+ LOGGER.warn("Lock node path seems to be null for task lock: {}, treating
release as a no-op", lock);
+ }
+
+ return status;
+ }
+
+ /**
+ * Force release the lock without checking if any tasks are in progress
+ */
+ public boolean forceReleaseLock(String tableNameWithType) {
+ LOGGER.info("Trying to force release the lock for table: {}",
tableNameWithType);
+ String lockPath = getLockPath(tableNameWithType);
+
+ boolean released = true;
+ if (!_propertyStore.exists(lockPath, AccessOption.EPHEMERAL)) {
+ LOGGER.info("No lock ZNode: {} found for table: {}, nothing to force
release", lockPath, tableNameWithType);
Review Comment:
done
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