Github user arina-ielchiieva commented on a diff in the pull request: https://github.com/apache/drill/pull/928#discussion_r142946871 --- Diff: exec/java-exec/src/main/java/org/apache/drill/exec/work/foreman/rm/DistributedQueryQueue.java --- @@ -0,0 +1,342 @@ +/* + * 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.drill.exec.work.foreman.rm; + +import java.util.concurrent.TimeUnit; + +import javax.xml.bind.annotation.XmlRootElement; + +import org.apache.drill.exec.ExecConstants; +import org.apache.drill.exec.coord.ClusterCoordinator; +import org.apache.drill.exec.coord.DistributedSemaphore; +import org.apache.drill.exec.coord.DistributedSemaphore.DistributedLease; +import org.apache.drill.exec.proto.UserBitShared.QueryId; +import org.apache.drill.exec.proto.helper.QueryIdHelper; +import org.apache.drill.exec.server.DrillbitContext; +import org.apache.drill.exec.server.options.SystemOptionManager; + +/** + * Distributed query queue which uses a Zookeeper distributed semaphore to + * control queuing across the cluster. The distributed queue is actually two + * queues: one for "small" queries, another for "large" queries. Query size is + * determined by the Planner's estimate of query cost. + * <p> + * This queue is configured using system options: + * <dl> + * <dt><tt>exec.queue.enable</tt> + * <dt> + * <dd>Set to true to enable the distributed queue.</dd> + * <dt><tt>exec.queue.large</tt> + * <dt> + * <dd>The maximum number of large queries to admit. Additional + * queries wait in the queue.</dd> + * <dt><tt>exec.queue.small</tt> + * <dt> + * <dd>The maximum number of small queries to admit. Additional + * queries wait in the queue.</dd> + * <dt><tt>exec.queue.threshold</tt> + * <dt> + * <dd>The cost threshold. Queries below this size are small, at + * or above this size are large..</dd> + * <dt><tt>exec.queue.timeout_millis</tt> + * <dt> + * <dd>The maximum time (in milliseconds) a query will wait in the + * queue before failing.</dd> + * </dl> + * <p> + * The above values are refreshed every five seconds. This aids performance + * a bit in systems with very high query arrival rates. + */ + +public class DistributedQueryQueue implements QueryQueue { + private static final org.slf4j.Logger logger = org.slf4j.LoggerFactory.getLogger(DistributedQueryQueue.class); + + private class DistributedQueueLease implements QueueLease { + private final QueryId queryId; + private DistributedLease lease; + private final String queueName; + + /** + * Memory allocated to the query. Though all queries in the queue use + * the same memory allocation rules, those rules can change at any time + * as the user changes system options. This value captures the value + * calculated at the time that this lease was granted. + */ + private long queryMemory; + + public DistributedQueueLease(QueryId queryId, String queueName, + DistributedLease lease, long queryMemory) { + this.queryId = queryId; + this.queueName = queueName; + this.lease = lease; + this.queryMemory = queryMemory; + } + + @Override + public String toString() { + return String.format("Lease for %s queue to query %s", + queueName, QueryIdHelper.getQueryId(queryId)); + } + + @Override + public long queryMemoryPerNode() { return queryMemory; } + + @Override + public void release() { + DistributedQueryQueue.this.release(this); + } + + @Override + public String queueName() { return queueName; } + } + + /** + * Exposes a snapshot of internal state information for use in status + * reporting, such as in the UI. + */ + + @XmlRootElement + public static class ZKQueueInfo { + public final int smallQueueSize; + public final int largeQueueSize; + public final double queueThreshold; + public final long memoryPerNode; + public final long memoryPerSmallQuery; + public final long memoryPerLargeQuery; + + public ZKQueueInfo(DistributedQueryQueue queue) { + smallQueueSize = queue.configSet.smallQueueSize; + largeQueueSize = queue.configSet.largeQueueSize; + queueThreshold = queue.configSet.queueThreshold; + memoryPerNode = queue.memoryPerNode; + memoryPerSmallQuery = queue.memoryPerSmallQuery; + memoryPerLargeQuery = queue.memoryPerLargeQuery; + } + } + + public interface StatusAdapter { + boolean inShutDown(); + } + + /** + * Holds runtime configuration options. Allows polling the options + * for changes, and easily detecting changes. + */ + + private static class ConfigSet { + private final long queueThreshold; + private final long queueTimeout; + private final int largeQueueSize; + private final int smallQueueSize; + private final double largeToSmallRatio; + private final double reserveMemoryRatio; + private final long minimumOperatorMemory; + + public ConfigSet(SystemOptionManager optionManager) { + queueThreshold = optionManager.getOption(ExecConstants.QUEUE_THRESHOLD_SIZE); + queueTimeout = optionManager.getOption(ExecConstants.QUEUE_TIMEOUT); + largeQueueSize = (int) optionManager.getOption(ExecConstants.LARGE_QUEUE_SIZE); + smallQueueSize = (int) optionManager.getOption(ExecConstants.SMALL_QUEUE_SIZE); + largeToSmallRatio = optionManager.getOption(ExecConstants.QUEUE_MEMORY_RATIO); + reserveMemoryRatio = optionManager.getOption(ExecConstants.QUEUE_MEMORY_RESERVE); + minimumOperatorMemory = optionManager.getOption(ExecConstants.MIN_MEMORY_PER_BUFFERED_OP); + } + + @Override + public boolean equals(Object other) { + if (other == null || ! (other instanceof ConfigSet)) { + return false; + } + ConfigSet otherSet = (ConfigSet) other; + return queueThreshold == otherSet.queueThreshold && + queueTimeout == otherSet.queueTimeout && + largeQueueSize == otherSet.largeQueueSize && + smallQueueSize == otherSet.smallQueueSize && + largeToSmallRatio == otherSet.largeToSmallRatio && + reserveMemoryRatio == otherSet.reserveMemoryRatio && + minimumOperatorMemory == otherSet.minimumOperatorMemory; + } + } + + private long memoryPerNode; + private SystemOptionManager optionManager; + private ConfigSet configSet; + private ClusterCoordinator clusterCoordinator; + private long refreshTime; + private long memoryPerSmallQuery; + private long memoryPerLargeQuery; + private final StatusAdapter statusAdapter; + + public DistributedQueryQueue(DrillbitContext context, StatusAdapter adapter) { + statusAdapter = adapter; + optionManager = context.getOptionManager(); + clusterCoordinator = context.getClusterCoordinator(); + } + + @Override + public void setMemoryPerNode(long memoryPerNode) { + this.memoryPerNode = memoryPerNode; + refreshConfig(); + } + + @Override + public long defaultQueryMemoryPerNode(double cost) { + return (cost < configSet.queueThreshold) + ? memoryPerSmallQuery + : memoryPerLargeQuery; + } + + @Override + public long minimumOperatorMemory() { return configSet.minimumOperatorMemory; } + + /** + * This limits the number of "small" and "large" queries that a Drill cluster will run + * simultaneously, if queuing is enabled. If the query is unable to run, this will block + * until it can. Beware that this is called under run(), and so will consume a Thread + * while it waits for the required distributed semaphore. + * + * @param queryId query identifier + * @param totalCost the query plan + * @throws QueryQueueException + * @throws QueueTimeoutException + */ + + @SuppressWarnings("resource") + @Override + public QueueLease enqueue(QueryId queryId, double cost) throws QueryQueueException, QueueTimeoutException { + final String queueName; + DistributedLease lease = null; + long queryMemory; + final DistributedSemaphore distributedSemaphore; + try { + + // Only the refresh and queue computation is synchronized. + + synchronized(this) { + refreshConfig(); + + // get the appropriate semaphore + if (cost >= configSet.queueThreshold) { + distributedSemaphore = clusterCoordinator.getSemaphore("query.large", configSet.largeQueueSize); + queueName = "large"; + queryMemory = memoryPerLargeQuery; + } else { + distributedSemaphore = clusterCoordinator.getSemaphore("query.small", configSet.smallQueueSize); + queueName = "small"; + queryMemory = memoryPerSmallQuery; + } + } + logger.debug("Query {} with cost {} placed into the {} queue.", + QueryIdHelper.getQueryId(queryId), cost, queueName); + + lease = distributedSemaphore.acquire(configSet.queueTimeout, TimeUnit.MILLISECONDS); + } catch (final Exception e) { + logger.error("Unable to acquire slot for query " + + QueryIdHelper.getQueryId(queryId), e); + throw new QueryQueueException("Unable to acquire slot for query.", e); + } + + if (lease == null) { + int timeoutSecs = (int) Math.round(configSet.queueTimeout/1000.0); + logger.warn("Queue timeout: {} after {} seconds.", queueName, timeoutSecs); + throw new QueueTimeoutException(queryId, queueName, timeoutSecs); + } + return new DistributedQueueLease(queryId, queueName, lease, queryMemory); + } + + private synchronized void refreshConfig() { + long now = System.currentTimeMillis(); + if (now < refreshTime) { --- End diff -- The same here. Do we need delay in refresh?
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