This is an automated email from the ASF dual-hosted git repository.
findepi pushed a commit to branch 1.6.x
in repository https://gitbox.apache.org/repos/asf/iceberg.git
The following commit(s) were added to refs/heads/1.6.x by this push:
new e18a2fe102 Core: Limit ParallelIterable memory consumption by yielding
in tasks (backport #10691) (#10787)
e18a2fe102 is described below
commit e18a2fe10214f5f3ffa0a317a28af8b2a619817a
Author: Raunaq Morarka <[email protected]>
AuthorDate: Fri Jul 26 21:50:25 2024 +0530
Core: Limit ParallelIterable memory consumption by yielding in tasks
(backport #10691) (#10787)
ParallelIterable schedules 2 * WORKER_THREAD_POOL_SIZE tasks for
processing input iterables. This defaults to 2 * # CPU cores. When one
or some of the input iterables are considerable in size and the
ParallelIterable consumer is not quick enough, this could result in
unbounded allocation inside `ParallelIterator.queue`. This commit bounds
the queue. When queue is full, the tasks yield and get removed from the
executor. They are resumed when consumer catches up.
(cherry picked from commit 7831a8dfc3a2de546ca069f4fc1e7afd03777554)
Co-authored-by: Piotr Findeisen <[email protected]>
---
.../org/apache/iceberg/util/ParallelIterable.java | 222 ++++++++++++++++-----
.../apache/iceberg/util/TestParallelIterable.java | 48 +++++
2 files changed, 215 insertions(+), 55 deletions(-)
diff --git a/core/src/main/java/org/apache/iceberg/util/ParallelIterable.java
b/core/src/main/java/org/apache/iceberg/util/ParallelIterable.java
index d7221e7d45..6486bd7fd4 100644
--- a/core/src/main/java/org/apache/iceberg/util/ParallelIterable.java
+++ b/core/src/main/java/org/apache/iceberg/util/ParallelIterable.java
@@ -20,84 +20,117 @@ package org.apache.iceberg.util;
import java.io.Closeable;
import java.io.IOException;
+import java.io.UncheckedIOException;
+import java.util.ArrayDeque;
+import java.util.Deque;
import java.util.Iterator;
import java.util.NoSuchElementException;
+import java.util.Optional;
+import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
-import java.util.concurrent.Future;
-import org.apache.iceberg.exceptions.RuntimeIOException;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.function.Supplier;
import org.apache.iceberg.io.CloseableGroup;
import org.apache.iceberg.io.CloseableIterable;
import org.apache.iceberg.io.CloseableIterator;
import org.apache.iceberg.relocated.com.google.common.base.Preconditions;
import org.apache.iceberg.relocated.com.google.common.collect.Iterables;
+import org.apache.iceberg.relocated.com.google.common.io.Closer;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
public class ParallelIterable<T> extends CloseableGroup implements
CloseableIterable<T> {
+
+ private static final Logger LOG =
LoggerFactory.getLogger(ParallelIterable.class);
+
+ // Logic behind default value: ParallelIterable is often used for file
planning.
+ // Assuming that a DataFile or DeleteFile is about 500 bytes, a 30k limit
uses 14.3 MB of memory.
+ private static final int DEFAULT_MAX_QUEUE_SIZE = 30_000;
+
private final Iterable<? extends Iterable<T>> iterables;
private final ExecutorService workerPool;
+ // Bound for number of items in the queue to limit memory consumption
+ // even in the case when input iterables are large.
+ private final int approximateMaxQueueSize;
+
public ParallelIterable(Iterable<? extends Iterable<T>> iterables,
ExecutorService workerPool) {
- this.iterables = iterables;
- this.workerPool = workerPool;
+ this(iterables, workerPool, DEFAULT_MAX_QUEUE_SIZE);
+ }
+
+ public ParallelIterable(
+ Iterable<? extends Iterable<T>> iterables,
+ ExecutorService workerPool,
+ int approximateMaxQueueSize) {
+ this.iterables = Preconditions.checkNotNull(iterables, "Input iterables
cannot be null");
+ this.workerPool = Preconditions.checkNotNull(workerPool, "Worker pool
cannot be null");
+ this.approximateMaxQueueSize = approximateMaxQueueSize;
}
@Override
public CloseableIterator<T> iterator() {
- ParallelIterator<T> iter = new ParallelIterator<>(iterables, workerPool);
+ ParallelIterator<T> iter =
+ new ParallelIterator<>(iterables, workerPool, approximateMaxQueueSize);
addCloseable(iter);
return iter;
}
private static class ParallelIterator<T> implements CloseableIterator<T> {
- private final Iterator<Runnable> tasks;
+ private final Iterator<Task<T>> tasks;
+ private final Deque<Task<T>> yieldedTasks = new ArrayDeque<>();
private final ExecutorService workerPool;
- private final Future<?>[] taskFutures;
+ private final CompletableFuture<Optional<Task<T>>>[] taskFutures;
private final ConcurrentLinkedQueue<T> queue = new
ConcurrentLinkedQueue<>();
- private volatile boolean closed = false;
+ private final int maxQueueSize;
+ private final AtomicBoolean closed = new AtomicBoolean(false);
private ParallelIterator(
- Iterable<? extends Iterable<T>> iterables, ExecutorService workerPool)
{
+ Iterable<? extends Iterable<T>> iterables, ExecutorService workerPool,
int maxQueueSize) {
this.tasks =
Iterables.transform(
- iterables,
- iterable ->
- (Runnable)
- () -> {
- try (Closeable ignored =
- (iterable instanceof Closeable) ? (Closeable)
iterable : () -> {}) {
- for (T item : iterable) {
- // exit manually because
`ConcurrentLinkedQueue` can't be
- // interrupted
- if (closed) {
- return;
- }
-
- queue.add(item);
- }
- } catch (IOException e) {
- throw new RuntimeIOException(e, "Failed to close
iterable");
- }
- })
+ iterables, iterable -> new Task<>(iterable, queue, closed,
maxQueueSize))
.iterator();
this.workerPool = workerPool;
+ this.maxQueueSize = maxQueueSize;
// submit 2 tasks per worker at a time
- this.taskFutures = new Future[2 * ThreadPools.WORKER_THREAD_POOL_SIZE];
+ this.taskFutures = new CompletableFuture[2 *
ThreadPools.WORKER_THREAD_POOL_SIZE];
}
@Override
public void close() {
// close first, avoid new task submit
- this.closed = true;
+ this.closed.set(true);
- // cancel background tasks
- for (Future<?> taskFuture : taskFutures) {
- if (taskFuture != null && !taskFuture.isDone()) {
- taskFuture.cancel(true);
+ try (Closer closer = Closer.create()) {
+ synchronized (this) {
+ yieldedTasks.forEach(closer::register);
+ yieldedTasks.clear();
}
+
+ // cancel background tasks and close continuations if any
+ for (CompletableFuture<Optional<Task<T>>> taskFuture : taskFutures) {
+ if (taskFuture != null) {
+ taskFuture.cancel(true);
+ taskFuture.thenAccept(
+ continuation -> {
+ if (continuation.isPresent()) {
+ try {
+ continuation.get().close();
+ } catch (IOException e) {
+ LOG.error("Task close failed", e);
+ }
+ }
+ });
+ }
+ }
+
+ // clean queue
+ this.queue.clear();
+ } catch (IOException e) {
+ throw new UncheckedIOException("Close failed", e);
}
- // clean queue
- this.queue.clear();
}
/**
@@ -107,15 +140,17 @@ public class ParallelIterable<T> extends CloseableGroup
implements CloseableIter
*
* @return true if there are pending tasks, false otherwise
*/
- private boolean checkTasks() {
+ private synchronized boolean checkTasks() {
+ Preconditions.checkState(!closed.get(), "Already closed");
boolean hasRunningTask = false;
for (int i = 0; i < taskFutures.length; i += 1) {
if (taskFutures[i] == null || taskFutures[i].isDone()) {
if (taskFutures[i] != null) {
- // check for task failure and re-throw any exception
+ // check for task failure and re-throw any exception. Enqueue
continuation if any.
try {
- taskFutures[i].get();
+ Optional<Task<T>> continuation = taskFutures[i].get();
+ continuation.ifPresent(yieldedTasks::addLast);
} catch (ExecutionException e) {
if (e.getCause() instanceof RuntimeException) {
// rethrow a runtime exception
@@ -136,30 +171,33 @@ public class ParallelIterable<T> extends CloseableGroup
implements CloseableIter
}
}
- return !closed && (tasks.hasNext() || hasRunningTask);
+ return !closed.get() && (tasks.hasNext() || hasRunningTask);
}
- private Future<?> submitNextTask() {
- if (!closed && tasks.hasNext()) {
- return workerPool.submit(tasks.next());
+ private CompletableFuture<Optional<Task<T>>> submitNextTask() {
+ if (!closed.get()) {
+ if (!yieldedTasks.isEmpty()) {
+ return CompletableFuture.supplyAsync(yieldedTasks.removeFirst(),
workerPool);
+ } else if (tasks.hasNext()) {
+ return CompletableFuture.supplyAsync(tasks.next(), workerPool);
+ }
}
return null;
}
@Override
public synchronized boolean hasNext() {
- Preconditions.checkState(!closed, "Already closed");
-
- // if the consumer is processing records more slowly than the producers,
then this check will
- // prevent tasks from being submitted. while the producers are running,
this will always
- // return here before running checkTasks. when enough of the tasks are
finished that the
- // consumer catches up, then lots of new tasks will be submitted at
once. this behavior is
- // okay because it ensures that records are not stacking up waiting to
be consumed and taking
- // up memory.
- //
- // consumers that process results quickly will periodically exhaust the
queue and submit new
- // tasks when checkTasks runs. fast consumers should not be delayed.
- if (!queue.isEmpty()) {
+ Preconditions.checkState(!closed.get(), "Already closed");
+
+ // If the consumer is processing records more slowly than the producers,
the producers will
+ // eventually fill the queue and yield, returning continuations.
Continuations and new tasks
+ // are started by checkTasks(). The check here prevents us from
restarting continuations or
+ // starting new tasks too early (when queue is almost full) or too late
(when queue is already
+ // emptied). Restarting too early would lead to tasks yielding very
quickly (CPU waste on
+ // scheduling). Restarting too late would mean the consumer may need to
wait for the tasks
+ // to produce new items. A consumer slower than producers shouldn't need
to wait.
+ int queueLowWaterMark = maxQueueSize / 2;
+ if (queue.size() > queueLowWaterMark) {
return true;
}
@@ -192,4 +230,78 @@ public class ParallelIterable<T> extends CloseableGroup
implements CloseableIter
return queue.poll();
}
}
+
+ private static class Task<T> implements Supplier<Optional<Task<T>>>,
Closeable {
+ private final Iterable<T> input;
+ private final ConcurrentLinkedQueue<T> queue;
+ private final AtomicBoolean closed;
+ private final int approximateMaxQueueSize;
+
+ private Iterator<T> iterator = null;
+
+ Task(
+ Iterable<T> input,
+ ConcurrentLinkedQueue<T> queue,
+ AtomicBoolean closed,
+ int approximateMaxQueueSize) {
+ this.input = Preconditions.checkNotNull(input, "input cannot be null");
+ this.queue = Preconditions.checkNotNull(queue, "queue cannot be null");
+ this.closed = Preconditions.checkNotNull(closed, "closed cannot be
null");
+ this.approximateMaxQueueSize = approximateMaxQueueSize;
+ }
+
+ @Override
+ public Optional<Task<T>> get() {
+ try {
+ if (iterator == null) {
+ iterator = input.iterator();
+ }
+
+ while (iterator.hasNext()) {
+ if (queue.size() >= approximateMaxQueueSize) {
+ // Yield when queue is over the size limit. Task will be
resubmitted later and continue
+ // the work.
+ return Optional.of(this);
+ }
+
+ T next = iterator.next();
+ if (closed.get()) {
+ break;
+ }
+
+ queue.add(next);
+ }
+ } catch (Throwable e) {
+ try {
+ close();
+ } catch (IOException closeException) {
+ // self-suppression is not permitted
+ // (e and closeException to be the same is unlikely, but possible)
+ if (closeException != e) {
+ e.addSuppressed(closeException);
+ }
+ }
+
+ throw e;
+ }
+
+ try {
+ close();
+ } catch (IOException e) {
+ throw new UncheckedIOException("Close failed", e);
+ }
+
+ // The task is complete. Returning empty means there is no continuation
that should be
+ // executed.
+ return Optional.empty();
+ }
+
+ @Override
+ public void close() throws IOException {
+ iterator = null;
+ if (input instanceof Closeable) {
+ ((Closeable) input).close();
+ }
+ }
+ }
}
diff --git
a/core/src/test/java/org/apache/iceberg/util/TestParallelIterable.java
b/core/src/test/java/org/apache/iceberg/util/TestParallelIterable.java
index af9c6ec521..4910732f6e 100644
--- a/core/src/test/java/org/apache/iceberg/util/TestParallelIterable.java
+++ b/core/src/test/java/org/apache/iceberg/util/TestParallelIterable.java
@@ -24,15 +24,22 @@ import java.io.IOException;
import java.lang.reflect.Field;
import java.util.Collections;
import java.util.Iterator;
+import java.util.List;
import java.util.Queue;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
+import java.util.stream.IntStream;
+import java.util.stream.Stream;
import org.apache.iceberg.io.CloseableIterable;
import org.apache.iceberg.io.CloseableIterator;
+import org.apache.iceberg.relocated.com.google.common.collect.HashMultiset;
+import org.apache.iceberg.relocated.com.google.common.collect.ImmutableList;
+import
org.apache.iceberg.relocated.com.google.common.collect.ImmutableMultiset;
import org.apache.iceberg.relocated.com.google.common.collect.Iterables;
import org.apache.iceberg.relocated.com.google.common.collect.Lists;
+import org.apache.iceberg.relocated.com.google.common.collect.Multiset;
import org.awaitility.Awaitility;
import org.junit.jupiter.api.Test;
@@ -133,6 +140,47 @@ public class TestParallelIterable {
.untilAsserted(() -> assertThat(queue).as("Queue is not empty after
cleaning").isEmpty());
}
+ @Test
+ public void limitQueueSize() throws IOException, IllegalAccessException,
NoSuchFieldException {
+
+ List<Iterable<Integer>> iterables =
+ ImmutableList.of(
+ () -> IntStream.range(0, 100).iterator(),
+ () -> IntStream.range(0, 100).iterator(),
+ () -> IntStream.range(0, 100).iterator());
+
+ Multiset<Integer> expectedValues =
+ IntStream.range(0, 100)
+ .boxed()
+ .flatMap(i -> Stream.of(i, i, i))
+ .collect(ImmutableMultiset.toImmutableMultiset());
+
+ int maxQueueSize = 20;
+ ExecutorService executor = Executors.newCachedThreadPool();
+ ParallelIterable<Integer> parallelIterable =
+ new ParallelIterable<>(iterables, executor, maxQueueSize);
+ CloseableIterator<Integer> iterator = parallelIterable.iterator();
+ Field queueField = iterator.getClass().getDeclaredField("queue");
+ queueField.setAccessible(true);
+ ConcurrentLinkedQueue<?> queue = (ConcurrentLinkedQueue<?>)
queueField.get(iterator);
+
+ Multiset<Integer> actualValues = HashMultiset.create();
+
+ while (iterator.hasNext()) {
+ assertThat(queue)
+ .as("iterator internal queue")
+ .hasSizeLessThanOrEqualTo(maxQueueSize + iterables.size());
+ actualValues.add(iterator.next());
+ }
+
+ assertThat(actualValues)
+ .as("multiset of values returned by the iterator")
+ .isEqualTo(expectedValues);
+
+ iterator.close();
+ executor.shutdownNow();
+ }
+
private void queueHasElements(CloseableIterator<Integer> iterator, Queue
queue) {
assertThat(iterator.hasNext()).isTrue();
assertThat(iterator.next()).isNotNull();
