amogh-jahagirdar commented on code in PR #14444: URL: https://github.com/apache/iceberg/pull/14444#discussion_r2481758787
########## core/src/main/java/org/apache/iceberg/ScanTasksIterable.java: ########## @@ -0,0 +1,276 @@ +/* + * 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.iceberg; + +import java.io.IOException; +import java.util.List; +import java.util.Map; +import java.util.NoSuchElementException; +import java.util.concurrent.BlockingQueue; +import java.util.concurrent.ConcurrentLinkedQueue; +import java.util.concurrent.ExecutorService; +import java.util.concurrent.LinkedBlockingQueue; +import java.util.concurrent.TimeUnit; +import java.util.concurrent.atomic.AtomicBoolean; +import java.util.concurrent.atomic.AtomicInteger; +import java.util.function.Supplier; +import org.apache.iceberg.catalog.TableIdentifier; +import org.apache.iceberg.io.CloseableIterable; +import org.apache.iceberg.io.CloseableIterator; +import org.apache.iceberg.relocated.com.google.common.annotations.VisibleForTesting; +import org.apache.iceberg.rest.ErrorHandlers; +import org.apache.iceberg.rest.ParserContext; +import org.apache.iceberg.rest.RESTClient; +import org.apache.iceberg.rest.ResourcePaths; +import org.apache.iceberg.rest.requests.FetchScanTasksRequest; +import org.apache.iceberg.rest.responses.FetchScanTasksResponse; +import org.apache.iceberg.util.ThreadPools; + +class ScanTasksIterable implements CloseableIterable<FileScanTask> { + + private static final int DEFAULT_TASK_QUEUE_CAPACITY = 1000; + + private static final long QUEUE_POLL_TIMEOUT_MS = 100; + + private static final int WORKER_POOL_SIZE = Math.max(1, ThreadPools.WORKER_THREAD_POOL_SIZE / 4); + + private final BlockingQueue<FileScanTask> taskQueue; + + private final ConcurrentLinkedQueue<String> planTasks; + + private final AtomicInteger activeWorkers = new AtomicInteger(0); + + private final AtomicBoolean shutdown = new AtomicBoolean(false); + + private final ExecutorService executorService; + + private final RESTClient client; + private final ResourcePaths resourcePaths; + private final TableIdentifier tableIdentifier; + private final Supplier<Map<String, String>> headers; + private final Map<Integer, PartitionSpec> specsById; + private final boolean caseSensitive; + private final Supplier<Boolean> cancellationCallback; + + ScanTasksIterable( + List<String> initialPlanTasks, + List<FileScanTask> initialFileScanTasks, + RESTClient client, + ResourcePaths resourcePaths, + TableIdentifier tableIdentifier, + Supplier<Map<String, String>> headers, + ExecutorService executorService, + Map<Integer, PartitionSpec> specsById, + boolean caseSensitive, + Supplier<Boolean> cancellationCallback) { + + this.taskQueue = new LinkedBlockingQueue<>(DEFAULT_TASK_QUEUE_CAPACITY); + this.planTasks = new ConcurrentLinkedQueue<>(); + + this.client = client; + this.resourcePaths = resourcePaths; + this.tableIdentifier = tableIdentifier; + this.headers = headers; + this.executorService = executorService; + this.specsById = specsById; + this.caseSensitive = caseSensitive; + this.cancellationCallback = cancellationCallback; + + if (initialFileScanTasks != null && !initialFileScanTasks.isEmpty()) { + for (FileScanTask task : initialFileScanTasks) { + try { + taskQueue.put(task); + } catch (InterruptedException e) { + Thread.currentThread().interrupt(); + throw new RuntimeException("Interrupted while adding initial tasks", e); + } + } + } + + if (initialPlanTasks != null && !initialPlanTasks.isEmpty()) { + planTasks.addAll(initialPlanTasks); + } + + submitFixedWorkers(); + } + + private void submitFixedWorkers() { + if (planTasks.isEmpty()) { + return; + } + + int numWorkers = Math.min(WORKER_POOL_SIZE, planTasks.size()); + + for (int i = 0; i < numWorkers; i++) { + executorService.execute(new PlanTaskWorker()); + } + } + + @Override + public CloseableIterator<FileScanTask> iterator() { + return new ScanTasksIterator(); + } + + @Override + public void close() throws IOException {} + + private class PlanTaskWorker implements Runnable { + + @Override + public void run() { + activeWorkers.incrementAndGet(); + + try { + while (true) { + if (shutdown.get()) { + return; + } + + String planTask = planTasks.poll(); + if (planTask == null) { + return; + } + + processPlanTask(planTask); + } + + } catch (InterruptedException e) { + Thread.currentThread().interrupt(); + } catch (Exception e) { + throw new RuntimeException("Worker failed processing planTask", e); + } finally { + int remaining = activeWorkers.decrementAndGet(); Review Comment: So I agree we need some form of reference counting on active workers or state tracking on plan tasks that are being "expanded" but not complete yet. one of the reasons I went with fork join pool in my approach was that I thought reference counting would be insufficient to preventing premature exit. I think my doubt was that it was possible for this line to decrement to 0, and before the execution of new plan task worker, the client consumer thread could see that there are no active workers, no leaf tasks, or no plan tasks and then prematurely exit (line 258) when another active worker is about to populate a plan task. I think I'm getting convinced that state is actually not possible because let's say. we decrement active workers to 0, the only possible way for there to be something about to add another plan task is if there is another active worker, which means that active workers would not be set to 0 to begin with. ########## core/src/main/java/org/apache/iceberg/ScanTasksIterable.java: ########## @@ -0,0 +1,276 @@ +/* + * 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.iceberg; + +import java.io.IOException; +import java.util.List; +import java.util.Map; +import java.util.NoSuchElementException; +import java.util.concurrent.BlockingQueue; +import java.util.concurrent.ConcurrentLinkedQueue; +import java.util.concurrent.ExecutorService; +import java.util.concurrent.LinkedBlockingQueue; +import java.util.concurrent.TimeUnit; +import java.util.concurrent.atomic.AtomicBoolean; +import java.util.concurrent.atomic.AtomicInteger; +import java.util.function.Supplier; +import org.apache.iceberg.catalog.TableIdentifier; +import org.apache.iceberg.io.CloseableIterable; +import org.apache.iceberg.io.CloseableIterator; +import org.apache.iceberg.relocated.com.google.common.annotations.VisibleForTesting; +import org.apache.iceberg.rest.ErrorHandlers; +import org.apache.iceberg.rest.ParserContext; +import org.apache.iceberg.rest.RESTClient; +import org.apache.iceberg.rest.ResourcePaths; +import org.apache.iceberg.rest.requests.FetchScanTasksRequest; +import org.apache.iceberg.rest.responses.FetchScanTasksResponse; +import org.apache.iceberg.util.ThreadPools; + +class ScanTasksIterable implements CloseableIterable<FileScanTask> { + + private static final int DEFAULT_TASK_QUEUE_CAPACITY = 1000; + + private static final long QUEUE_POLL_TIMEOUT_MS = 100; + + private static final int WORKER_POOL_SIZE = Math.max(1, ThreadPools.WORKER_THREAD_POOL_SIZE / 4); + + private final BlockingQueue<FileScanTask> taskQueue; + + private final ConcurrentLinkedQueue<String> planTasks; + + private final AtomicInteger activeWorkers = new AtomicInteger(0); + + private final AtomicBoolean shutdown = new AtomicBoolean(false); + + private final ExecutorService executorService; + + private final RESTClient client; + private final ResourcePaths resourcePaths; + private final TableIdentifier tableIdentifier; + private final Supplier<Map<String, String>> headers; + private final Map<Integer, PartitionSpec> specsById; + private final boolean caseSensitive; + private final Supplier<Boolean> cancellationCallback; + + ScanTasksIterable( + List<String> initialPlanTasks, + List<FileScanTask> initialFileScanTasks, + RESTClient client, + ResourcePaths resourcePaths, + TableIdentifier tableIdentifier, + Supplier<Map<String, String>> headers, + ExecutorService executorService, + Map<Integer, PartitionSpec> specsById, + boolean caseSensitive, + Supplier<Boolean> cancellationCallback) { + + this.taskQueue = new LinkedBlockingQueue<>(DEFAULT_TASK_QUEUE_CAPACITY); + this.planTasks = new ConcurrentLinkedQueue<>(); + + this.client = client; + this.resourcePaths = resourcePaths; + this.tableIdentifier = tableIdentifier; + this.headers = headers; + this.executorService = executorService; + this.specsById = specsById; + this.caseSensitive = caseSensitive; + this.cancellationCallback = cancellationCallback; + + if (initialFileScanTasks != null && !initialFileScanTasks.isEmpty()) { + for (FileScanTask task : initialFileScanTasks) { + try { + taskQueue.put(task); + } catch (InterruptedException e) { + Thread.currentThread().interrupt(); + throw new RuntimeException("Interrupted while adding initial tasks", e); + } + } + } + + if (initialPlanTasks != null && !initialPlanTasks.isEmpty()) { + planTasks.addAll(initialPlanTasks); + } + + submitFixedWorkers(); + } + + private void submitFixedWorkers() { + if (planTasks.isEmpty()) { + return; + } + + int numWorkers = Math.min(WORKER_POOL_SIZE, planTasks.size()); + + for (int i = 0; i < numWorkers; i++) { + executorService.execute(new PlanTaskWorker()); + } + } + + @Override + public CloseableIterator<FileScanTask> iterator() { + return new ScanTasksIterator(); + } + + @Override + public void close() throws IOException {} + + private class PlanTaskWorker implements Runnable { + + @Override + public void run() { + activeWorkers.incrementAndGet(); + + try { + while (true) { + if (shutdown.get()) { + return; + } + + String planTask = planTasks.poll(); + if (planTask == null) { + return; + } + + processPlanTask(planTask); + } + + } catch (InterruptedException e) { + Thread.currentThread().interrupt(); + } catch (Exception e) { + throw new RuntimeException("Worker failed processing planTask", e); + } finally { + int remaining = activeWorkers.decrementAndGet(); Review Comment: TLDR, I think this approach should work. -- 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]
