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Posted to commits@druid.apache.org by "abhishekrb19 (via GitHub)" <gi...@apache.org> on 2026/02/20 22:45:02 UTC
[PR] Extend server priorities to Peon servers (druid)
abhishekrb19 opened a new pull request, #19040:
URL: https://github.com/apache/druid/pull/19040
Fixes https://github.com/apache/druid/issues/19018
This change introduces `serverPriorityToReplicaCount` allowing operators to control the number of replicas per server priority. This ties into Druid’s query prioritization and [routing](https://druid.apache.org/docs/latest/configuration/#query-routing) strategies for Peon servers, similar to how it works for Historicals and Brokers.
This enables cluster operators to configure and isolate Peon replicas for mixed workload use cases in high SLA environments. For example, some replicas can be configured to handle queries of all priorities, while others may only respond to specific priority ranges.
Approach:
To support this, a new `serverPriorityToReplicaCount` property is added to the supervisor’s `ioConfig`.
The `SeekableStreamSupervisor` assigns priorities to `SeekableStreamIndexTask`s as they are created for a group. Similarly they're removed from internal bookkeeping when the tasks terminate. The `ForkingTaskRunner` then passes the appropriate server priority when initializing the Peon server. In the absence of this configuration, Peons continue to run with the default priority 0.
`serverPriorityToReplicaCount` is optional and is compatible with the existing `replicas` property if specified.
Note: I’ve intentionally excluded Kinesis and Rabbit supervisors for now to limit the scope and testing. These should be straightforward to add in a follow-up once this implementation is reviewed.
TODO: Add additional tests and documentation.
This PR has:
- [ ] been self-reviewed.
- [ ] using the [concurrency checklist](https://github.com/apache/druid/blob/master/dev/code-review/concurrency.md) (Remove this item if the PR doesn't have any relation to concurrency.)
- [ ] added documentation for new or modified features or behaviors.
- [ ] a release note entry in the PR description.
- [ ] added Javadocs for most classes and all non-trivial methods. Linked related entities via Javadoc links.
- [ ] added or updated version, license, or notice information in [licenses.yaml](https://github.com/apache/druid/blob/master/dev/license.md)
- [ ] added comments explaining the "why" and the intent of the code wherever would not be obvious for an unfamiliar reader.
- [ ] added unit tests or modified existing tests to cover new code paths, ensuring the threshold for [code coverage](https://github.com/apache/druid/blob/master/dev/code-review/code-coverage.md) is met.
- [ ] added integration tests.
- [ ] been tested in a test Druid cluster.
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Re: [PR] Extend server priorities to realtime indexing tasks for query isolation (druid)
Posted by "aho135 (via GitHub)" <gi...@apache.org>.
aho135 commented on code in PR #19040:
URL: https://github.com/apache/druid/pull/19040#discussion_r2874791674
##########
docs/ingestion/supervisor.md:
##########
@@ -65,6 +65,7 @@ For configuration properties specific to Kafka and Kinesis, see [Kafka I/O confi
|`lateMessageRejectionPeriod`|ISO 8601 period|Configures tasks to reject messages with timestamps earlier than this period before the task was created. For example, if this property is set to `PT1H` and the supervisor creates a task at `2016-01-01T12:00Z`, Druid drops messages with timestamps earlier than `2016-01-01T11:00Z`. This may help prevent concurrency issues if your data stream has late messages and you have multiple pipelines that need to operate on the same segments, such as a streaming and a nightly batch ingestion pipeline. You can specify only one of the late message rejection properties.|No||
|`earlyMessageRejectionPeriod`|ISO 8601 period|Configures tasks to reject messages with timestamps later than this period after the task reached its task duration. For example, if this property is set to `PT1H`, the task duration is set to `PT1H` and the supervisor creates a task at `2016-01-01T12:00Z`, Druid drops messages with timestamps later than `2016-01-01T14:00Z`. Tasks sometimes run past their task duration, such as in cases of supervisor failover.|No||
|`stopTaskCount`|Integer|Limits the number of ingestion tasks Druid can cycle at any given time. If not set, Druid can cycle all tasks at the same time. If set to a value less than `taskCount`, your cluster needs fewer available slots to run the supervisor. You can save costs by scaling down your ingestion tier, but this can lead to slower cycle times and lag. See [`stopTaskCount`](#stoptaskcount) for more information.|No|`taskCount` value|
+|`serverPriorityToReplicas`|Object (`Map<Integer, Integer>`)|Map of server priorities to the number of replicas per priority. When set, each task replica is assigned a server priority that corresponds to `druid.server.priority` on the Peon process to enable query isolation for mixed workloads using [query routing strategies](../configuration/index.md#query-routing). If not configured, the `replicas` setting applies and all task replicas are assigned a default priority of 0.<br/><br/>For example, setting `serverPriorityToReplicas` to `{"1": 2, "0": 1}` creates 2 task replicas with `druid.server.priority=1` and 1 task replica with `druid.server.priority=0` per task group. This configuration scales proportionally with `taskCount`. For example, if `taskCount` is set to 5, this results in 15 total tasks - 10 tasks with priority 1 and 5 tasks with priority 0.|No|null|
Review Comment:
```suggestion
|`serverPriorityToReplicas`|Object (`Map<Integer, Integer>`)|Map of server priorities to the number of replicas per priority. When set, each task replica is assigned a server priority that corresponds to `druid.server.priority` on the Peon process to enable query isolation for mixed workloads using [query routing strategies](../configuration/index.md#query-routing). If not configured, the `replicas` setting applies and all task replicas are assigned a default priority of 0.<br/><br/>For example, setting `replicas` to 3 and `serverPriorityToReplicas` to `{"1": 2, "0": 1}` creates 2 task replicas with `druid.server.priority=1` and 1 task replica with `druid.server.priority=0` per task group. This configuration scales proportionally with `taskCount`. For example, if `taskCount` is set to 5, this results in 15 total tasks - 10 tasks with priority 1 and 5 tasks with priority 0.|No|null|
```
This helps make it more clear that the sum of Replicas has to equal configured `replicas`
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Re: [PR] Extend server priorities to realtime indexing tasks for query isolation (druid)
Posted by "abhishekrb19 (via GitHub)" <gi...@apache.org>.
abhishekrb19 commented on code in PR #19040:
URL: https://github.com/apache/druid/pull/19040#discussion_r2876125797
##########
indexing-service/src/main/java/org/apache/druid/indexing/seekablestream/supervisor/SeekableStreamSupervisor.java:
##########
@@ -276,6 +277,25 @@ Set<String> taskIds()
return tasks.keySet();
}
+ /**
+ * Removes a task from {@link #tasks} and {@link #taskIdToServerPriority}.
+ */
+ void removeTask(String taskId)
+ {
+ tasks.remove(taskId);
+ taskIdToServerPriority.remove(taskId);
+ }
+
+ /**
+ * Removes a task from {@link #tasks} using the provided iterator and also removes the corresponding entry
+ * in {@link #taskIdToServerPriority}. Useful when removing tasks during iteration.
+ */
+ void removeTask(Iterator<Entry<String, TaskData>> taskDataIterator, String taskId)
+ {
+ taskDataIterator.remove();
Review Comment:
This is already an iterator from `tasks.keySet()`, so it does remove the entry from `tasks`. I’ve updated the javadoc to clarify that and added a test as well
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Re: [PR] Extend server priorities to realtime indexing tasks for query isolation (druid)
Posted by "abhishekrb19 (via GitHub)" <gi...@apache.org>.
abhishekrb19 commented on code in PR #19040:
URL: https://github.com/apache/druid/pull/19040#discussion_r2875276730
##########
extensions-core/kafka-indexing-service/src/test/java/org/apache/druid/indexing/kafka/supervisor/KafkaSupervisorTest.java:
##########
@@ -5244,6 +5272,112 @@ public void test_autoScaler_doesNotRepeatScaleDownActions_ifTasksAreStillPublish
Assert.assertFalse(supervisor.getPartitionOffsets().isEmpty());
}
+ @Test
+ public void testComputeUnassignedServerPriorities_whenMultipleReplicasPerPriorityIsSet()
+ {
+ final Map<String, Object> consumerProperties = KafkaConsumerConfigs.getConsumerProperties();
+ consumerProperties.put("bootstrap.servers", kafkaHost);
+
+ final KafkaSupervisorIOConfig kafkaSupervisorIOConfig = new KafkaSupervisorIOConfig(
+ topic,
+ null,
+ INPUT_FORMAT,
+ null,
Review Comment:
Yeah, it's verified in this test `SeekableStreamSupervisorIOConfigTest#testMismatchBetweenReplicasAndServerPriorityReplicasThrowsException()`
(In terms of structure, I added most tests to the seekable stream package for code coverage, since it serves as the base implementation and added a subset of those tests to the specific supervisor types)
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Re: [PR] Extend server priorities to realtime indexing tasks for query isolation (druid)
Posted by "abhishekrb19 (via GitHub)" <gi...@apache.org>.
abhishekrb19 commented on code in PR #19040:
URL: https://github.com/apache/druid/pull/19040#discussion_r2873858671
##########
indexing-service/src/main/java/org/apache/druid/indexing/seekablestream/supervisor/SeekableStreamSupervisorIOConfig.java:
##########
@@ -119,6 +121,28 @@ public SeekableStreamSupervisorIOConfig(
}
this.idleConfig = idleConfig;
+ this.serverPriorityToReplicas = serverPriorityToReplicas;
+ if (this.serverPriorityToReplicas != null) {
+ final int serverPriorityReplicas = this.serverPriorityToReplicas.values().stream().mapToInt(Integer::intValue).sum();
Review Comment:
Yep, good point. I’ve made the validation check stricter to use >= 0 since the existing `replicas` can be set to 0
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Re: [PR] Extend server priorities to realtime indexing tasks for query isolation (druid)
Posted by "abhishekrb19 (via GitHub)" <gi...@apache.org>.
abhishekrb19 commented on code in PR #19040:
URL: https://github.com/apache/druid/pull/19040#discussion_r2862091030
##########
indexing-service/src/main/java/org/apache/druid/indexing/seekablestream/supervisor/SeekableStreamSupervisorIOConfig.java:
##########
@@ -119,6 +121,21 @@ public SeekableStreamSupervisorIOConfig(
}
this.idleConfig = idleConfig;
+ this.serverPriorityToReplicas = serverPriorityToReplicas;
+ if (this.serverPriorityToReplicas != null) {
+ final int replicaCount = this.serverPriorityToReplicas.values().stream().mapToInt(Integer::intValue).sum();
+ if (replicas != null && replicas != replicaCount) {
+ throw InvalidInput.exception(
Review Comment:
This would be triggered only if someone unintentionally sets conflicting values that cause ambiguity. I wanted to keep the behavior straightforward for end users rather than document any precedence rules in such cases. I've updated the error message accordingly, please let me know if that makes sense.
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Re: [PR] Extend server priorities to realtime indexing tasks for query isolation (druid)
Posted by "jtuglu1 (via GitHub)" <gi...@apache.org>.
jtuglu1 commented on code in PR #19040:
URL: https://github.com/apache/druid/pull/19040#discussion_r2875707861
##########
indexing-service/src/main/java/org/apache/druid/indexing/seekablestream/supervisor/SeekableStreamSupervisor.java:
##########
@@ -276,6 +277,25 @@ Set<String> taskIds()
return tasks.keySet();
}
+ /**
+ * Removes a task from {@link #tasks} and {@link #taskIdToServerPriority}.
+ */
+ void removeTask(String taskId)
+ {
+ tasks.remove(taskId);
+ taskIdToServerPriority.remove(taskId);
+ }
+
+ /**
+ * Removes a task from {@link #tasks} using the provided iterator and also removes the corresponding entry
+ * in {@link #taskIdToServerPriority}. Useful when removing tasks during iteration.
+ */
+ void removeTask(Iterator<Entry<String, TaskData>> taskDataIterator, String taskId)
+ {
+ taskDataIterator.remove();
Review Comment:
Do we not need to remove taskId from `tasks`? If not, can we document why not?
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Re: [PR] Extend server priorities to realtime indexing tasks for query isolation (druid)
Posted by "aho135 (via GitHub)" <gi...@apache.org>.
aho135 commented on code in PR #19040:
URL: https://github.com/apache/druid/pull/19040#discussion_r2874952416
##########
extensions-core/kafka-indexing-service/src/test/java/org/apache/druid/indexing/kafka/supervisor/KafkaSupervisorTest.java:
##########
@@ -5244,6 +5272,112 @@ public void test_autoScaler_doesNotRepeatScaleDownActions_ifTasksAreStillPublish
Assert.assertFalse(supervisor.getPartitionOffsets().isEmpty());
}
+ @Test
+ public void testComputeUnassignedServerPriorities_whenMultipleReplicasPerPriorityIsSet()
+ {
+ final Map<String, Object> consumerProperties = KafkaConsumerConfigs.getConsumerProperties();
+ consumerProperties.put("bootstrap.servers", kafkaHost);
+
+ final KafkaSupervisorIOConfig kafkaSupervisorIOConfig = new KafkaSupervisorIOConfig(
+ topic,
+ null,
+ INPUT_FORMAT,
+ null,
Review Comment:
Did you want to enforce `replicas = sum of Replicas configured in serverPriorityToReplicas`?
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Re: [PR] Extend server priorities to realtime indexing tasks for query isolation (druid)
Posted by "abhishekrb19 (via GitHub)" <gi...@apache.org>.
abhishekrb19 merged PR #19040:
URL: https://github.com/apache/druid/pull/19040
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Re: [PR] Extend server priorities to Peon servers (druid)
Posted by "github-advanced-security[bot] (via GitHub)" <gi...@apache.org>.
github-advanced-security[bot] commented on code in PR #19040:
URL: https://github.com/apache/druid/pull/19040#discussion_r2835441319
##########
indexing-service/src/main/java/org/apache/druid/indexing/seekablestream/supervisor/SeekableStreamSupervisor.java:
##########
@@ -4508,7 +4549,8 @@
TreeMap<Integer, Map<PartitionIdType, SequenceOffsetType>> sequenceOffsets,
SeekableStreamIndexTaskIOConfig taskIoConfig,
SeekableStreamIndexTaskTuningConfig taskTuningConfig,
- RowIngestionMetersFactory rowIngestionMetersFactory
+ RowIngestionMetersFactory rowIngestionMetersFactory,
Review Comment:
## Useless parameter
The parameter 'rowIngestionMetersFactory' is never used.
[Show more details](https://github.com/apache/druid/security/code-scanning/10822)
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Re: [PR] Extend server priorities to realtime indexing tasks for query isolation (druid)
Posted by "jtuglu1 (via GitHub)" <gi...@apache.org>.
jtuglu1 commented on code in PR #19040:
URL: https://github.com/apache/druid/pull/19040#discussion_r2875707861
##########
indexing-service/src/main/java/org/apache/druid/indexing/seekablestream/supervisor/SeekableStreamSupervisor.java:
##########
@@ -276,6 +277,25 @@ Set<String> taskIds()
return tasks.keySet();
}
+ /**
+ * Removes a task from {@link #tasks} and {@link #taskIdToServerPriority}.
+ */
+ void removeTask(String taskId)
+ {
+ tasks.remove(taskId);
+ taskIdToServerPriority.remove(taskId);
+ }
+
+ /**
+ * Removes a task from {@link #tasks} using the provided iterator and also removes the corresponding entry
+ * in {@link #taskIdToServerPriority}. Useful when removing tasks during iteration.
+ */
+ void removeTask(Iterator<Entry<String, TaskData>> taskDataIterator, String taskId)
+ {
+ taskDataIterator.remove();
Review Comment:
do we not need to remove taskId from `tasks`?
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Re: [PR] Extend server priorities to realtime indexing tasks for query isolation (druid)
Posted by "abhishekrb19 (via GitHub)" <gi...@apache.org>.
abhishekrb19 commented on PR #19040:
URL: https://github.com/apache/druid/pull/19040#issuecomment-3988026508
Thanks for the reviews @aho135 and @jtuglu1! Jesse, please feel free to share any feedback even after the PR is merged and I can address it in a follow-up.
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Re: [PR] Extend server priorities to realtime indexing tasks for query isolation (druid)
Posted by "github-advanced-security[bot] (via GitHub)" <gi...@apache.org>.
github-advanced-security[bot] commented on code in PR #19040:
URL: https://github.com/apache/druid/pull/19040#discussion_r2839536791
##########
indexing-service/src/test/java/org/apache/druid/indexing/seekablestream/supervisor/SeekableStreamSupervisorStateTest.java:
##########
@@ -2773,6 +2805,93 @@
verifyAll();
}
+ @Test
+ public void testComputeUnassignedServerPriorities_whenMultipleReplicasPerPriorityIsSet()
+ {
+ final SeekableStreamSupervisorIOConfig ioConfig = new SeekableStreamSupervisorIOConfig(
+ STREAM,
+ new JsonInputFormat(new JSONPathSpec(true, List.of()), Map.of(), false, false, false),
+ null,
+ 1,
+ new Period("PT1H"),
+ new Period("P1D"),
+ new Period("PT30S"),
+ true,
+ new Period("PT30M"),
+ null,
+ null,
+ null,
+ LagAggregator.DEFAULT,
+ null,
+ null,
+ null,
+ Map.of(
+ 10, 2,
+ 20, 3
+ )
+ ){};
+
+ Assert.assertEquals(5, (int) ioConfig.getReplicas());
+
+ EasyMock.reset(spec);
+ EasyMock.expect(spec.getId()).andReturn(SUPERVISOR_ID).anyTimes();
+ EasyMock.expect(spec.getSupervisorStateManagerConfig()).andReturn(supervisorConfig).anyTimes();
+ EasyMock.expect(spec.getDataSchema()).andReturn(getDataSchema()).anyTimes();
Review Comment:
## Deprecated method or constructor invocation
Invoking [SeekableStreamSupervisorSpec.getDataSchema](1) should be avoided because it has been deprecated.
[Show more details](https://github.com/apache/druid/security/code-scanning/10823)
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Re: [PR] Extend server priorities to realtime indexing tasks for query isolation (druid)
Posted by "aho135 (via GitHub)" <gi...@apache.org>.
aho135 commented on code in PR #19040:
URL: https://github.com/apache/druid/pull/19040#discussion_r2874791674
##########
docs/ingestion/supervisor.md:
##########
@@ -65,6 +65,7 @@ For configuration properties specific to Kafka and Kinesis, see [Kafka I/O confi
|`lateMessageRejectionPeriod`|ISO 8601 period|Configures tasks to reject messages with timestamps earlier than this period before the task was created. For example, if this property is set to `PT1H` and the supervisor creates a task at `2016-01-01T12:00Z`, Druid drops messages with timestamps earlier than `2016-01-01T11:00Z`. This may help prevent concurrency issues if your data stream has late messages and you have multiple pipelines that need to operate on the same segments, such as a streaming and a nightly batch ingestion pipeline. You can specify only one of the late message rejection properties.|No||
|`earlyMessageRejectionPeriod`|ISO 8601 period|Configures tasks to reject messages with timestamps later than this period after the task reached its task duration. For example, if this property is set to `PT1H`, the task duration is set to `PT1H` and the supervisor creates a task at `2016-01-01T12:00Z`, Druid drops messages with timestamps later than `2016-01-01T14:00Z`. Tasks sometimes run past their task duration, such as in cases of supervisor failover.|No||
|`stopTaskCount`|Integer|Limits the number of ingestion tasks Druid can cycle at any given time. If not set, Druid can cycle all tasks at the same time. If set to a value less than `taskCount`, your cluster needs fewer available slots to run the supervisor. You can save costs by scaling down your ingestion tier, but this can lead to slower cycle times and lag. See [`stopTaskCount`](#stoptaskcount) for more information.|No|`taskCount` value|
+|`serverPriorityToReplicas`|Object (`Map<Integer, Integer>`)|Map of server priorities to the number of replicas per priority. When set, each task replica is assigned a server priority that corresponds to `druid.server.priority` on the Peon process to enable query isolation for mixed workloads using [query routing strategies](../configuration/index.md#query-routing). If not configured, the `replicas` setting applies and all task replicas are assigned a default priority of 0.<br/><br/>For example, setting `serverPriorityToReplicas` to `{"1": 2, "0": 1}` creates 2 task replicas with `druid.server.priority=1` and 1 task replica with `druid.server.priority=0` per task group. This configuration scales proportionally with `taskCount`. For example, if `taskCount` is set to 5, this results in 15 total tasks - 10 tasks with priority 1 and 5 tasks with priority 0.|No|null|
Review Comment:
```suggestion
|`serverPriorityToReplicas`|Object (`Map<Integer, Integer>`)|Map of server priorities to the number of replicas per priority. When set, each task replica is assigned a server priority that corresponds to `druid.server.priority` on the Peon process to enable query isolation for mixed workloads using [query routing strategies](../configuration/index.md#query-routing). If not configured, the `replicas` setting applies and all task replicas are assigned a default priority of 0.<br/><br/>For example, setting `replicas` to 3 and `serverPriorityToReplicas` to `{"1": 2, "0": 1}` creates 2 task replicas with `druid.server.priority=1` and 1 task replica with `druid.server.priority=0` per task group. This configuration scales proportionally with `taskCount`. For example, if `taskCount` is set to 5, this results in 15 total tasks - 10 tasks with priority 1 and 5 tasks with priority 0.|No|null|
```
This helps make it more clear that the sum or Replicas has to equal configured `replicas`
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