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https://issues.apache.org/jira/browse/HADOOP-19303?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17929239#comment-17929239
]
ASF GitHub Bot commented on HADOOP-19303:
-----------------------------------------
mukund-thakur commented on code in PR #7418:
URL: https://github.com/apache/hadoop/pull/7418#discussion_r1966018354
##########
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/RawLocalFileSystem.java:
##########
@@ -319,74 +321,125 @@ AsynchronousFileChannel getAsyncChannel() throws
IOException {
@Override
public void readVectored(List<? extends FileRange> ranges,
IntFunction<ByteBuffer> allocate) throws
IOException {
+ readVectored(ranges, allocate, LOG_BYTE_BUFFER_RELEASED);
+ }
+
+ @Override
+ public void readVectored(final List<? extends FileRange> ranges,
+ final IntFunction<ByteBuffer> allocate,
+ final Consumer<ByteBuffer> release) throws IOException {
// Validate, but do not pass in a file length as it may change.
List<? extends FileRange> sortedRanges = sortRangeList(ranges);
- // Set up all of the futures, so that we can use them if things fail
- for(FileRange range: sortedRanges) {
+ // Set up all of the futures, so that the caller can await on
+ // their competion.
+ for (FileRange range: sortedRanges) {
validateRangeRequest(range);
range.setData(new CompletableFuture<>());
}
- try {
- AsynchronousFileChannel channel = getAsyncChannel();
- ByteBuffer[] buffers = new ByteBuffer[sortedRanges.size()];
- AsyncHandler asyncHandler = new AsyncHandler(channel, sortedRanges,
buffers);
- for(int i = 0; i < sortedRanges.size(); ++i) {
- FileRange range = sortedRanges.get(i);
- buffers[i] = allocate.apply(range.getLength());
- channel.read(buffers[i], range.getOffset(), i, asyncHandler);
- }
- } catch (IOException ioe) {
- LOG.debug("Exception occurred during vectored read ", ioe);
Review Comment:
seems like this was unnecessary. Any failure will automatically be caught in
failed() method.
##########
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/PositionedReadable.java:
##########
@@ -136,4 +137,30 @@ default void readVectored(List<? extends FileRange> ranges,
IntFunction<ByteBuffer> allocate) throws
IOException {
VectoredReadUtils.readVectored(this, ranges, allocate);
}
+
+ /**
+ * Variant of {@link #readVectored(List, IntFunction)} where a release()
function
+ * may be invoked if problems surface during reads -this method is called to
+ * try to return any allocated buffer which has not been read yet.
+ * Buffers which have successfully been read and returned to the caller do
not
+ * get released: this is for failures only.
+ * <p>
+ * The default implementation calls readVectored/2 so as to ensure that
+ * if an existing stream implementation does not implement this method
+ * all is good.
+ * <p>
+ * Implementations SHOULD override this method if they can release buffers as
+ * part of their error handling.
+ * @param ranges the byte ranges to read
+ * @param allocate the function to allocate ByteBuffer
Review Comment:
nit: remove "the"
##########
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/PositionedReadable.java:
##########
@@ -136,4 +137,30 @@ default void readVectored(List<? extends FileRange> ranges,
IntFunction<ByteBuffer> allocate) throws
IOException {
VectoredReadUtils.readVectored(this, ranges, allocate);
}
+
+ /**
+ * Variant of {@link #readVectored(List, IntFunction)} where a release()
function
+ * may be invoked if problems surface during reads -this method is called to
+ * try to return any allocated buffer which has not been read yet.
+ * Buffers which have successfully been read and returned to the caller do
not
+ * get released: this is for failures only.
+ * <p>
+ * The default implementation calls readVectored/2 so as to ensure that
+ * if an existing stream implementation does not implement this method
+ * all is good.
+ * <p>
+ * Implementations SHOULD override this method if they can release buffers as
+ * part of their error handling.
+ * @param ranges the byte ranges to read
+ * @param allocate the function to allocate ByteBuffer
+ * @param release the function to release a ByteBuffer.
Review Comment:
nit: remove "the"
##########
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/impl/VectorIOBufferPool.java:
##########
@@ -0,0 +1,80 @@
+/*
+ * 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.hadoop.fs.impl;
+
+import java.nio.ByteBuffer;
+import java.util.function.Consumer;
+import java.util.function.IntFunction;
+
+import org.apache.hadoop.io.ByteBufferPool;
+
+import static java.util.Objects.requireNonNull;
+
+/**
+ * A ByteBufferPool implementation that uses a pair of functions to allocate
+ * and release ByteBuffers; intended for use implementing the VectorIO API
+ * as it makes the pair of functions easier to pass around and use in
+ * existing code.
+ * <p>
+ * No matter what kind of buffer is requested, the allocation function
+ * is invoked; that is: the direct flag is ignored.
+ */
+public final class VectorIOBufferPool implements ByteBufferPool {
Review Comment:
why do we need this when we have WeakReferencedElasticByteBufferPool ? An
actual implementation of release function should call putBuffer() of the
WeakReferencedElasticByteBufferPool no?
##########
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/VectoredReadUtils.java:
##########
@@ -52,6 +53,15 @@ public final class VectoredReadUtils {
private static final Logger LOG =
LoggerFactory.getLogger(VectoredReadUtils.class);
+ /**
+ * This releaser just logs at debug that the buffer
+ * was released.
+ */
+ public static final Consumer<ByteBuffer> LOG_BYTE_BUFFER_RELEASED =
+ (buffer) -> {
+ LOG.debug("release buffer {}", buffer.toString());
Review Comment:
should we parameterize and add. releasing buffer for range[x-y] ?
> VectorIO API to support releasing buffers on failure
> ----------------------------------------------------
>
> Key: HADOOP-19303
> URL: https://issues.apache.org/jira/browse/HADOOP-19303
> Project: Hadoop Common
> Issue Type: Sub-task
> Components: fs, fs/s3
> Affects Versions: 3.4.1
> Reporter: Steve Loughran
> Assignee: Steve Loughran
> Priority: Major
> Labels: pull-request-available
>
> extend for vector IO API with a method that takes a ByteBufferPool
> implementation rather than just an allocator. This allows for buffers to be
> returned to the pool when problems occur, before throwing an exception.
> The Parquet API is already designed for this
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