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https://issues.apache.org/jira/browse/HADOOP-11867?focusedWorklogId=486857&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-486857
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ASF GitHub Bot logged work on HADOOP-11867:
-------------------------------------------
Author: ASF GitHub Bot
Created on: 21/Sep/20 10:23
Start Date: 21/Sep/20 10:23
Worklog Time Spent: 10m
Work Description: steveloughran commented on a change in pull request
#1830:
URL: https://github.com/apache/hadoop/pull/1830#discussion_r491936825
##########
File path:
hadoop-common-project/benchmark/src/main/java/org/apache/hadoop/benchmark/AsyncBenchmark.java
##########
@@ -0,0 +1,242 @@
+/*
+ * 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.benchmark;
+
+import org.apache.hadoop.conf.Configuration;
Review comment:
review import ordering
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Issue Time Tracking
-------------------
Worklog Id: (was: 486857)
Time Spent: 1h 50m (was: 1h 40m)
> FS API: Add a high-performance vectored Read to FSDataInputStream API
> ---------------------------------------------------------------------
>
> Key: HADOOP-11867
> URL: https://issues.apache.org/jira/browse/HADOOP-11867
> Project: Hadoop Common
> Issue Type: New Feature
> Components: fs, fs/azure, fs/s3, hdfs-client
> Affects Versions: 3.0.0
> Reporter: Gopal Vijayaraghavan
> Assignee: Owen O'Malley
> Priority: Major
> Labels: performance, pull-request-available
> Time Spent: 1h 50m
> Remaining Estimate: 0h
>
> The most significant way to read from a filesystem in an efficient way is to
> let the FileSystem implementation handle the seek behaviour underneath the
> API to be the most efficient as possible.
> A better approach to the seek problem is to provide a sequence of read
> locations as part of a single call, while letting the system schedule/plan
> the reads ahead of time.
> This is exceedingly useful for seek-heavy readers on HDFS, since this allows
> for potentially optimizing away the seek-gaps within the FSDataInputStream
> implementation.
> For seek+read systems with even more latency than locally-attached disks,
> something like a {{readFully(long[] offsets, ByteBuffer[] chunks)}} would
> take of the seeks internally while reading chunk.remaining() bytes into each
> chunk (which may be {{slice()}}ed off a bigger buffer).
> The base implementation can stub in this as a sequence of seeks + read() into
> ByteBuffers, without forcing each FS implementation to override this in any
> way.
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