LakshSingla commented on code in PR #14808: URL: https://github.com/apache/druid/pull/14808#discussion_r1306937152
########## server/src/main/java/org/apache/druid/server/SubqueryLimitUtils.java: ########## @@ -0,0 +1,132 @@ +/* + * 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.druid.server; + +import org.apache.druid.error.InvalidInput; +import org.apache.druid.java.util.common.logger.Logger; +import org.apache.druid.query.lookup.LookupExtractor; +import org.apache.druid.query.lookup.LookupExtractorFactoryContainer; +import org.apache.druid.query.lookup.LookupExtractorFactoryContainerProvider; + +public class SubqueryLimitUtils +{ + private static final double SUBQUERY_MEMORY_BYTES_FRACTION = 0.5; + private static final Logger log = new Logger(SubqueryLimitUtils.class); + + + public static final String UNLIMITED_LIMIT_VALUE = "unlimited"; + public static final String AUTO_LIMIT_VALUE = "auto"; + + public static final Long UNLIMITED_LIMIT_REPRESENTATION = -1L; + + private final long autoLimitBytes; + + public SubqueryLimitUtils( + final LookupExtractorFactoryContainerProvider lookupManager, + final long maxMemoryInJvm, + final int brokerNumHttpConnections + ) + { + autoLimitBytes = computeLimitBytesForAuto(lookupManager, maxMemoryInJvm, brokerNumHttpConnections); + } + + public long convertSubqueryLimitStringToLong(final String maxSubqueryLimit) + { + if (UNLIMITED_LIMIT_VALUE.equalsIgnoreCase(maxSubqueryLimit)) { + return UNLIMITED_LIMIT_REPRESENTATION; + } + if (AUTO_LIMIT_VALUE.equalsIgnoreCase(maxSubqueryLimit)) { + return autoLimitBytes; + } + + long retVal; + try { + retVal = Long.parseLong(maxSubqueryLimit); + } + catch (NumberFormatException e) { + throw InvalidInput.exception( + e, + "Unable to parse the provided maxSubqueryLimit [%s] to a valid number. Valid values for the " + + "maxSubqueryLimits can be 'auto', 'unlimited' or a positive number representing bytes to reserve.", + maxSubqueryLimit + ); + } + + // This can happen if the provided number is greater than Longs.MAX_VALUE + if (retVal < 0) { + throw InvalidInput.exception("Limit too large"); + } + + return retVal; + } + + /** + * Computes the byte limit when 'auto' is passed as a parameter. This computes the total heap space available + * for the subquery inlining by getting a fraction of the total heap space in JVM, removing the size of the lookups, + * and dividing it by the maximum concurrent queries that can run. Maximum concurrent queries that Druid can + * run is usually limited by its broker's http threadpool size + */ + private static long computeLimitBytesForAuto( + final LookupExtractorFactoryContainerProvider lookupManager, + final long maxMemoryInJvm, + final int brokerNumHttpConnections + ) + { + long memoryInJvmWithoutLookups = maxMemoryInJvm - computeLookupFootprint(lookupManager); + long memoryInJvmForSubqueryResultsInlining = (long) (memoryInJvmWithoutLookups * SUBQUERY_MEMORY_BYTES_FRACTION); + long memoryInJvmForSubqueryResultsInliningPerQuery = memoryInJvmForSubqueryResultsInlining + / brokerNumHttpConnections; + return Math.max(memoryInJvmForSubqueryResultsInliningPerQuery, 1L); + } + + /** + * Computes the size occupied by the lookups. If the size of the lookup cannot be computed, it skips over the lookup + */ + private static long computeLookupFootprint(final LookupExtractorFactoryContainerProvider lookupManager) + { + + if (lookupManager == null || lookupManager.getAllLookupNames() == null) { + log.warn("Failed to get the lookupManager for estimating lookup size. Skipping."); + return 0; + } + + int lookupCount = 0; + long lookupFootprint = 0; + + for (final String lookupName : lookupManager.getAllLookupNames()) { + final LookupExtractorFactoryContainer container = lookupManager.get(lookupName).orElse(null); + + if (container != null) { + try { + final LookupExtractor extractor = container.getLookupExtractorFactory().get(); Review Comment: 1. Lookups are usually loaded completely on the startup for querying processes. The behavior is handled by the flag - `enableLookupSyncOnStartup` which ensures that it is ideally set to true for the brokers. 2. Considering that a single entry takes about 100 bytes in the map table, a 100KB lookup would have about 1000 entries. Iterating over it a single time should be fine I think. For larger lookups, however, say unusual cases where the size of the lookup is over a limit, we can have some heuristics instead. 3. Since we do `estimateHeapFootprint` for every MSQ query, I think it should be relatively safe to include one time at the broker startup time. WDYT? -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
