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https://issues.apache.org/jira/browse/PARQUET-2149?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17540200#comment-17540200
]
ASF GitHub Bot commented on PARQUET-2149:
-----------------------------------------
parthchandra commented on code in PR #968:
URL: https://github.com/apache/parquet-mr/pull/968#discussion_r877587287
##########
parquet-hadoop/src/main/java/org/apache/parquet/hadoop/ColumnChunkPageReadStore.java:
##########
@@ -21,12 +21,15 @@
import java.io.IOException;
import java.util.ArrayDeque;
import java.util.HashMap;
+import java.util.Iterator;
Review Comment:
Yeah. This and a bunch of other imports are not used. Removing them all.
##########
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);
+
+ final SeekableInputStream fileInputStream;
+ int fetchIndex = 0;
+ int readIndex = 0;
+ ExecutorService threadPool;
+ LinkedBlockingQueue<Future<Void>> readFutures;
+ boolean closed = false;
+
+ LongAdder totalTimeBlocked = new LongAdder();
+ LongAdder totalCountBlocked = new LongAdder();
+ LongAccumulator maxTimeBlocked = new LongAccumulator(Long::max, 0L);
Review Comment:
Done
##########
parquet-hadoop/src/main/java/org/apache/parquet/hadoop/ColumnChunkPageReadStore.java:
##########
@@ -21,12 +21,15 @@
import java.io.IOException;
import java.util.ArrayDeque;
import java.util.HashMap;
+import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Optional;
import java.util.PrimitiveIterator;
import java.util.Queue;
+import java.util.concurrent.LinkedBlockingDeque;
+import org.apache.parquet.ParquetRuntimeException;
Review Comment:
Removed
> 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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