FrankChen021 commented on code in PR #19687:
URL: https://github.com/apache/druid/pull/19687#discussion_r3720545431
##########
indexing-service/src/main/java/org/apache/druid/indexing/overlord/supervisor/SupervisorManager.java:
##########
@@ -644,6 +648,90 @@ public boolean isAnotherTaskGroupPublishingToPartitions(
}
}
+ /**
+ * Simulates the effects of the {@code costBased} auto-scaler by computing
the optimal
+ * task count under various values of aggregate lag.
+ */
+ public Map<String, Object> simulateAutoscaling(
+ String supervisorId,
+ CostBasedAutoScalerConfig config,
+ int maxProcessingRatePerTask,
+ @Nullable Integer requestedTaskCount
+ )
+ {
+ // Validate that this is a SeekableStreamSupervisor
+ final Pair<Supervisor, SupervisorSpec> supervisorPair =
supervisors.get(supervisorId);
+ if (supervisorPair == null || supervisorPair.rhs == null ||
supervisorPair.lhs == null) {
+ throw NotFound.exception("Invalid supervisor[%s]", supervisorId);
+ } else if (!(supervisorPair.rhs instanceof SeekableStreamSupervisorSpec)) {
+ throw InvalidInput.exception(
+ "Cannot simulate autoscaling for supervisor[%s] of type[%s]",
+ supervisorId, supervisorPair.rhs.getType()
+ );
+ }
+
+ final SeekableStreamSupervisorSpec supervisorSpec =
(SeekableStreamSupervisorSpec) supervisorPair.rhs;
+
+ // Validate the inputs
+ final long criticalLag =
Configs.valueOrDefault(config.getCriticalLagThreshold(), 1_000_000);
+ InvalidInput.conditionalException(
+ criticalLag >= 1000,
+ "Value of critical lag[%d] must be 1000 or more",
+ criticalLag
+ );
+ InvalidInput.conditionalException(
+ maxProcessingRatePerTask >= 100,
+ "Value of maxProcessingRatePerTask[%d] must be 100 events per second
or more",
+ maxProcessingRatePerTask
+ );
+ InvalidInput.conditionalException(
+ requestedTaskCount == null
+ || (requestedTaskCount >= config.getTaskCountMin() &&
requestedTaskCount <= config.getTaskCountMax()),
+ "Value of currentTaskCount[%d] must be within taskCountMin[%d] and
taskCountMax[%d]",
+ requestedTaskCount, config.getTaskCountMin(), config.getTaskCountMax()
+ );
+
+ // Simulate from the supervisor's live task count unless the caller pins
one.
+ final int currentTaskCount = supervisorSpec.getIoConfig().getTaskCount();
+ final int simulationTaskCount = Math.max(
+ config.getTaskCountMin(),
+ Math.min(
+ Configs.valueOrDefault(requestedTaskCount, currentTaskCount),
+ config.getTaskCountMax()
+ )
+ );
+
+ // Use the partition count and task duration from the supervisor spec
+ final int partitionCount = ((SeekableStreamSupervisor<?, ?, ?>)
supervisorPair.lhs).getKnownPartitionCount();
+ final long taskDurationSeconds =
supervisorSpec.getIoConfig().getTaskDuration().getStandardSeconds();
+
+ // Assume that the tasks are fully used since there is some lag
+ final double idleRatio = config.getOptimalTaskIdleRatio();
+
+ // Invoke the cost function for lag in the range [0, 2 *
criticalLagThreshold)
+ final Object[] rows = new Object[200];
+ final int lagStepSize = (int) (criticalLag / 100);
+ final CostBasedAutoScaler autoscaleSimulator =
CostBasedAutoScaler.createSimulator(config, supervisorId);
+ for (int i = 0; i < 200; ++i) {
+ final double observedAggregateLag = (double) lagStepSize * i;
+ final CostMetrics costMetrics = new CostMetrics(
+ observedAggregateLag / partitionCount,
+ observedAggregateLag,
+ simulationTaskCount,
+ partitionCount,
+ idleRatio,
+ taskDurationSeconds,
+ maxProcessingRatePerTask,
+ maxProcessingRatePerTask * 1.0
+ );
+ final int optimalTaskCount =
autoscaleSimulator.computeOptimalTaskCountInternal(costMetrics, true);
Review Comment:
[P2] Suppress every simulator log path
Passing `true` suppresses the normal computation logs, but the high- and
critical-lag branches in `computeOptimalTaskCountInternal` still log
unconditionally. Each request evaluates 200 points; with the standard 0-to-2x
range, 125 of them cross the 0.75x high-lag threshold and emit INFO records.
Guard those branches with `!isSimulation` as well.
##########
indexing-service/src/main/java/org/apache/druid/indexing/overlord/supervisor/SupervisorManager.java:
##########
@@ -644,6 +648,90 @@ public boolean isAnotherTaskGroupPublishingToPartitions(
}
}
+ /**
+ * Simulates the effects of the {@code costBased} auto-scaler by computing
the optimal
+ * task count under various values of aggregate lag.
+ */
+ public Map<String, Object> simulateAutoscaling(
+ String supervisorId,
+ CostBasedAutoScalerConfig config,
+ int maxProcessingRatePerTask,
+ @Nullable Integer requestedTaskCount
+ )
+ {
+ // Validate that this is a SeekableStreamSupervisor
+ final Pair<Supervisor, SupervisorSpec> supervisorPair =
supervisors.get(supervisorId);
+ if (supervisorPair == null || supervisorPair.rhs == null ||
supervisorPair.lhs == null) {
+ throw NotFound.exception("Invalid supervisor[%s]", supervisorId);
+ } else if (!(supervisorPair.rhs instanceof SeekableStreamSupervisorSpec)) {
+ throw InvalidInput.exception(
+ "Cannot simulate autoscaling for supervisor[%s] of type[%s]",
+ supervisorId, supervisorPair.rhs.getType()
+ );
+ }
+
+ final SeekableStreamSupervisorSpec supervisorSpec =
(SeekableStreamSupervisorSpec) supervisorPair.rhs;
+
+ // Validate the inputs
+ final long criticalLag =
Configs.valueOrDefault(config.getCriticalLagThreshold(), 1_000_000);
+ InvalidInput.conditionalException(
+ criticalLag >= 1000,
+ "Value of critical lag[%d] must be 1000 or more",
+ criticalLag
+ );
+ InvalidInput.conditionalException(
+ maxProcessingRatePerTask >= 100,
+ "Value of maxProcessingRatePerTask[%d] must be 100 events per second
or more",
+ maxProcessingRatePerTask
+ );
+ InvalidInput.conditionalException(
Review Comment:
[P2] Reject non-positive task-count bounds
The simulation config accepts `taskCountMin=0`, and a positive live task
count then reaches `computeValidTaskCounts`, which divides by `taskCountMin`
and returns HTTP 500. Restore validation that both task-count bounds are at
least one before running the simulation.
##########
indexing-service/src/main/java/org/apache/druid/indexing/overlord/supervisor/SupervisorManager.java:
##########
@@ -644,6 +648,90 @@ public boolean isAnotherTaskGroupPublishingToPartitions(
}
}
+ /**
+ * Simulates the effects of the {@code costBased} auto-scaler by computing
the optimal
+ * task count under various values of aggregate lag.
+ */
+ public Map<String, Object> simulateAutoscaling(
+ String supervisorId,
+ CostBasedAutoScalerConfig config,
+ int maxProcessingRatePerTask,
+ @Nullable Integer requestedTaskCount
+ )
+ {
+ // Validate that this is a SeekableStreamSupervisor
+ final Pair<Supervisor, SupervisorSpec> supervisorPair =
supervisors.get(supervisorId);
+ if (supervisorPair == null || supervisorPair.rhs == null ||
supervisorPair.lhs == null) {
+ throw NotFound.exception("Invalid supervisor[%s]", supervisorId);
+ } else if (!(supervisorPair.rhs instanceof SeekableStreamSupervisorSpec)) {
+ throw InvalidInput.exception(
+ "Cannot simulate autoscaling for supervisor[%s] of type[%s]",
+ supervisorId, supervisorPair.rhs.getType()
+ );
+ }
+
+ final SeekableStreamSupervisorSpec supervisorSpec =
(SeekableStreamSupervisorSpec) supervisorPair.rhs;
+
+ // Validate the inputs
+ final long criticalLag =
Configs.valueOrDefault(config.getCriticalLagThreshold(), 1_000_000);
+ InvalidInput.conditionalException(
+ criticalLag >= 1000,
+ "Value of critical lag[%d] must be 1000 or more",
+ criticalLag
+ );
+ InvalidInput.conditionalException(
+ maxProcessingRatePerTask >= 100,
+ "Value of maxProcessingRatePerTask[%d] must be 100 events per second
or more",
+ maxProcessingRatePerTask
+ );
+ InvalidInput.conditionalException(
+ requestedTaskCount == null
+ || (requestedTaskCount >= config.getTaskCountMin() &&
requestedTaskCount <= config.getTaskCountMax()),
+ "Value of currentTaskCount[%d] must be within taskCountMin[%d] and
taskCountMax[%d]",
+ requestedTaskCount, config.getTaskCountMin(), config.getTaskCountMax()
+ );
+
+ // Simulate from the supervisor's live task count unless the caller pins
one.
+ final int currentTaskCount = supervisorSpec.getIoConfig().getTaskCount();
+ final int simulationTaskCount = Math.max(
+ config.getTaskCountMin(),
+ Math.min(
+ Configs.valueOrDefault(requestedTaskCount, currentTaskCount),
+ config.getTaskCountMax()
+ )
+ );
+
+ // Use the partition count and task duration from the supervisor spec
+ final int partitionCount = ((SeekableStreamSupervisor<?, ?, ?>)
supervisorPair.lhs).getKnownPartitionCount();
Review Comment:
[P2] Reject unavailable live partition topology
`getKnownPartitionCount()` is zero during startup and temporarily after
repartitioning clears assignments. In that state every simulated point returns
`CANNOT_COMPUTE` (`taskCount=-1`) in an otherwise successful response,
producing a bogus chart. Return a retryable or invalid-input error until a
positive live partition count is available.
##########
indexing-service/src/main/java/org/apache/druid/indexing/overlord/supervisor/SupervisorResource.java:
##########
@@ -534,6 +537,31 @@ public Response terminateAll(@Context final
HttpServletRequest req)
);
}
+ @POST
+ @Path("/{id}/autoscaler/simulate")
+ @Consumes(MediaType.APPLICATION_JSON)
+ @Produces(MediaType.APPLICATION_JSON)
+ @ResourceFilters(SupervisorResourceFilter.class)
Review Comment:
[P2] Authorize simulation as read-only
`SupervisorResourceFilter` maps every POST to `Action.WRITE`, so read-only
users who can inspect this supervisor receive 403 for a computation that
changes no state. The prior authorization finding remains unresolved; use an
explicit datasource READ authorization path for this endpoint.
##########
indexing-service/src/main/java/org/apache/druid/indexing/overlord/supervisor/SupervisorManager.java:
##########
@@ -644,6 +648,90 @@ public boolean isAnotherTaskGroupPublishingToPartitions(
}
}
+ /**
+ * Simulates the effects of the {@code costBased} auto-scaler by computing
the optimal
+ * task count under various values of aggregate lag.
+ */
+ public Map<String, Object> simulateAutoscaling(
+ String supervisorId,
+ CostBasedAutoScalerConfig config,
+ int maxProcessingRatePerTask,
+ @Nullable Integer requestedTaskCount
+ )
+ {
+ // Validate that this is a SeekableStreamSupervisor
+ final Pair<Supervisor, SupervisorSpec> supervisorPair =
supervisors.get(supervisorId);
+ if (supervisorPair == null || supervisorPair.rhs == null ||
supervisorPair.lhs == null) {
+ throw NotFound.exception("Invalid supervisor[%s]", supervisorId);
+ } else if (!(supervisorPair.rhs instanceof SeekableStreamSupervisorSpec)) {
+ throw InvalidInput.exception(
+ "Cannot simulate autoscaling for supervisor[%s] of type[%s]",
+ supervisorId, supervisorPair.rhs.getType()
+ );
+ }
+
+ final SeekableStreamSupervisorSpec supervisorSpec =
(SeekableStreamSupervisorSpec) supervisorPair.rhs;
+
+ // Validate the inputs
+ final long criticalLag =
Configs.valueOrDefault(config.getCriticalLagThreshold(), 1_000_000);
+ InvalidInput.conditionalException(
+ criticalLag >= 1000,
+ "Value of critical lag[%d] must be 1000 or more",
+ criticalLag
+ );
+ InvalidInput.conditionalException(
+ maxProcessingRatePerTask >= 100,
+ "Value of maxProcessingRatePerTask[%d] must be 100 events per second
or more",
+ maxProcessingRatePerTask
+ );
+ InvalidInput.conditionalException(
+ requestedTaskCount == null
+ || (requestedTaskCount >= config.getTaskCountMin() &&
requestedTaskCount <= config.getTaskCountMax()),
+ "Value of currentTaskCount[%d] must be within taskCountMin[%d] and
taskCountMax[%d]",
+ requestedTaskCount, config.getTaskCountMin(), config.getTaskCountMax()
+ );
+
+ // Simulate from the supervisor's live task count unless the caller pins
one.
+ final int currentTaskCount = supervisorSpec.getIoConfig().getTaskCount();
+ final int simulationTaskCount = Math.max(
+ config.getTaskCountMin(),
+ Math.min(
+ Configs.valueOrDefault(requestedTaskCount, currentTaskCount),
+ config.getTaskCountMax()
+ )
+ );
+
+ // Use the partition count and task duration from the supervisor spec
+ final int partitionCount = ((SeekableStreamSupervisor<?, ?, ?>)
supervisorPair.lhs).getKnownPartitionCount();
+ final long taskDurationSeconds =
supervisorSpec.getIoConfig().getTaskDuration().getStandardSeconds();
+
+ // Assume that the tasks are fully used since there is some lag
+ final double idleRatio = config.getOptimalTaskIdleRatio();
+
+ // Invoke the cost function for lag in the range [0, 2 *
criticalLagThreshold)
+ final Object[] rows = new Object[200];
+ final int lagStepSize = (int) (criticalLag / 100);
Review Comment:
[P3] Preserve the long critical-lag range
`criticalLagThreshold` is a `long`, but casting its step to `int` overflows
once the threshold exceeds 214,748,364,700. Valid larger thresholds therefore
produce wrapped negative or truncated lag points. Keep `lagStepSize` as `long`
or `double`.
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