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https://issues.apache.org/jira/browse/PARQUET-2149?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17642875#comment-17642875
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ASF GitHub Bot commented on PARQUET-2149:
-----------------------------------------
shangxinli commented on code in PR #968:
URL: https://github.com/apache/parquet-mr/pull/968#discussion_r1038808056
##########
parquet-common/src/main/java/org/apache/parquet/bytes/AsyncMultiBufferInputStream.java:
##########
@@ -0,0 +1,162 @@
+/*
+ * 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.parquet.bytes;
+
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.util.List;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Future;
+import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.LongAccumulator;
+import java.util.concurrent.atomic.LongAdder;
+import org.apache.parquet.io.SeekableInputStream;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+class AsyncMultiBufferInputStream extends MultiBufferInputStream {
+
+ private static final Logger LOG =
LoggerFactory.getLogger(AsyncMultiBufferInputStream.class);
+
+ private int fetchIndex = 0;
+ private final SeekableInputStream fileInputStream;
+ private int readIndex = 0;
+ private ExecutorService threadPool;
+ private LinkedBlockingQueue<Future<Void>> readFutures;
+ private boolean closed = false;
+
+ private LongAdder totalTimeBlocked = new LongAdder();
+ private LongAdder totalCountBlocked = new LongAdder();
+ private LongAccumulator maxTimeBlocked = new LongAccumulator(Long::max, 0L);
+
+ AsyncMultiBufferInputStream(ExecutorService threadPool, SeekableInputStream
fileInputStream,
+ List<ByteBuffer> buffers) {
+ super(buffers);
+ this.fileInputStream = fileInputStream;
+ this.threadPool = threadPool;
+ readFutures = new LinkedBlockingQueue<>(buffers.size());
+ if (LOG.isDebugEnabled()) {
+ LOG.debug("ASYNC: Begin read into buffers ");
+ for (ByteBuffer buf : buffers) {
+ LOG.debug("ASYNC: buffer {} ", buf);
+ }
+ }
+ fetchAll();
+ }
+
+ private void checkState() {
+ if (closed) {
+ throw new RuntimeException("Stream is closed");
+ }
+ }
+
+ private void fetchAll() {
+ checkState();
+ submitReadTask(0);
+ }
+
+ private void submitReadTask(int bufferNo) {
+ ByteBuffer buffer = buffers.get(bufferNo);
+ try {
+ readFutures.put(threadPool.submit(() -> {
+ readOneBuffer(buffer);
+ if (bufferNo < buffers.size() - 1) {
+ submitReadTask(bufferNo + 1);
+ }
+ return null;
+ })
+ );
+ } catch (InterruptedException e) {
+ Thread.currentThread().interrupt();
+ throw new RuntimeException(e);
+ }
+ }
+
+ private void readOneBuffer(ByteBuffer buffer) {
+ long startTime = System.nanoTime();
+ try {
+ fileInputStream.readFully(buffer);
+ buffer.flip();
+ long readCompleted = System.nanoTime();
+ long timeSpent = readCompleted - startTime;
+ LOG.debug("ASYNC Stream: READ - {}", timeSpent / 1000.0);
+ fetchIndex++;
+ } catch (IOException e) {
+ throw new RuntimeException(e);
+ }
+ }
+
+ @Override
+ public boolean nextBuffer() {
+ checkState();
+ // hack: parent constructor can call this method before this class is
fully initialized.
Review Comment:
I see the comment with 'hack'. What is the proper implementation?
> Implement async IO for Parquet file reader
> ------------------------------------------
>
> Key: PARQUET-2149
> URL: https://issues.apache.org/jira/browse/PARQUET-2149
> Project: Parquet
> Issue Type: Improvement
> Components: parquet-mr
> Reporter: Parth Chandra
> Priority: Major
>
> ParquetFileReader's implementation has the following flow (simplified) -
> - For every column -> Read from storage in 8MB blocks -> Read all
> uncompressed pages into output queue
> - From output queues -> (downstream ) decompression + decoding
> This flow is serialized, which means that downstream threads are blocked
> until the data has been read. Because a large part of the time spent is
> waiting for data from storage, threads are idle and CPU utilization is really
> low.
> There is no reason why this cannot be made asynchronous _and_ parallel. So
> For Column _i_ -> reading one chunk until end, from storage -> intermediate
> output queue -> read one uncompressed page until end -> output queue ->
> (downstream ) decompression + decoding
> Note that this can be made completely self contained in ParquetFileReader and
> downstream implementations like Iceberg and Spark will automatically be able
> to take advantage without code change as long as the ParquetFileReader apis
> are not changed.
> In past work with async io [Drill - async page reader
> |https://github.com/apache/drill/blob/master/exec/java-exec/src/main/java/org/apache/drill/exec/store/parquet/columnreaders/AsyncPageReader.java]
> , I have seen 2x-3x improvement in reading speed for Parquet files.
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