yashmayya commented on code in PR #14574:
URL: https://github.com/apache/pinot/pull/14574#discussion_r1886880302
##########
pinot-broker/src/main/java/org/apache/pinot/broker/requesthandler/MultiStageBrokerRequestHandler.java:
##########
@@ -224,67 +227,89 @@ protected BrokerResponse handleRequest(long requestId,
String query, SqlNodeAndO
return new
BrokerResponseNative(QueryException.getException(QueryException.QUOTA_EXCEEDED_ERROR,
errorMessage));
}
- Tracing.ThreadAccountantOps.setupRunner(String.valueOf(requestId),
ThreadExecutionContext.TaskType.MSE);
-
- long executionStartTimeNs = System.nanoTime();
- QueryDispatcher.QueryResult queryResults;
+ Timer queryTimer = new Timer(queryTimeoutMs);
try {
- queryResults =
- _queryDispatcher.submitAndReduce(requestContext,
dispatchableSubPlan, queryTimeoutMs, queryOptions);
- } catch (TimeoutException e) {
- for (String table : tableNames) {
- _brokerMetrics.addMeteredTableValue(table,
BrokerMeter.BROKER_RESPONSES_WITH_TIMEOUTS, 1);
+ // It's fine to block in this thread because we use a separate thread
pool from the main Jersey server to process
+ // these requests.
+ if (!_querySemaphore.tryAcquire(queryTimeoutMs, TimeUnit.MILLISECONDS)) {
+ LOGGER.warn("Timed out waiting to execute request {}: {}", requestId,
query);
+
requestContext.setErrorCode(QueryException.EXECUTION_TIMEOUT_ERROR_CODE);
+ return new
BrokerResponseNative(QueryException.EXECUTION_TIMEOUT_ERROR);
}
- LOGGER.warn("Timed out executing request {}: {}", requestId, query);
+ } catch (InterruptedException e) {
+ LOGGER.warn("Interrupt received while waiting to execute request {}:
{}", requestId, query);
requestContext.setErrorCode(QueryException.EXECUTION_TIMEOUT_ERROR_CODE);
return new BrokerResponseNative(QueryException.EXECUTION_TIMEOUT_ERROR);
Review Comment:
We could either add a debug / info log showing this queueing / throttling
mechanism based wait time per query or add a new metric to show the number of
queries that timed out while waiting to be dispatched (or both). WDYT?
##########
pinot-broker/src/main/java/org/apache/pinot/broker/requesthandler/MultiStageQuerySemaphore.java:
##########
@@ -0,0 +1,174 @@
+/**
+ * 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.broker.requesthandler;
+
+import com.google.common.base.Preconditions;
+import java.util.Collections;
+import java.util.concurrent.Semaphore;
+import java.util.concurrent.TimeUnit;
+import org.apache.helix.HelixAdmin;
+import org.apache.helix.HelixConstants;
+import org.apache.helix.HelixManager;
+import org.apache.helix.model.HelixConfigScope;
+import org.apache.helix.model.builder.HelixConfigScopeBuilder;
+import org.apache.pinot.broker.broker.helix.ClusterChangeHandler;
+import org.apache.pinot.spi.utils.CommonConstants;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+
+/**
+ * This class helps limit the number of multi-stage queries being executed
concurrently. Currently, this limit is
+ * applied at the broker level, but could be moved to the server level in the
future.
+ */
+public class MultiStageQuerySemaphore extends Semaphore implements
ClusterChangeHandler {
Review Comment:
Good point, I've split up this class into two new ones -
`MultiStageQueryThrottler` which implements the `ClusterChangeHandler`
interface and `AdjustableSemaphore` which is now a generic util class. I've
preferred to keep the minimal interfaces because I don't feel like the amount
of mocking required for testing here is too high, but I'd be happy to
reconsider if you feel strongly about it.
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