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https://issues.apache.org/jira/browse/HADOOP-15027?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16251109#comment-16251109
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wujinhu commented on HADOOP-15027:
----------------------------------
[~uncleGen]
I have set up hadoop env in Tencent cloud server, and read data from Aliyun OSS
via hadoop command
file size: 104MB,
When I tested aggressive random read, I divided this file into multipart(each
part is 1MB) and shuffle all the parts to read.
{code:java}
public static final String MULTIPART_DOWNLOAD_SIZE_KEY =
"fs.oss.multipart.download.size";
public static final long MULTIPART_DOWNLOAD_SIZE_DEFAULT = 1 * 1024 * 1024;
{code}
Current version
ubuntu@VM-0-11-ubuntu:~/hadoop-3.0.0-beta1$ date; hadoop fs -cat
oss://hadoop-on-oss/hadoop/wordcount/wordcount_bigdata_100M.txt > /dev/null;
date
Tue Nov 14 15:47:27 CST 2017
Tue Nov 14 15:48:47 CST 2017
80s
After optimized by multi-thread prefetch
-----------------------------------
fs.oss.multipart.download.ahead.part.max.number = 1
fs.oss.multipart.download.threads = 4
sequential IO: 77s
random IO: 74.51s
-----------------------------------
fs.oss.multipart.download.ahead.part.max.number = 8
fs.oss.multipart.download.threads = 4
sequential IO: 23s
random IO: 59.128
-----------------------------------
fs.oss.multipart.download.ahead.part.max.number = 16
fs.oss.multipart.download.threads = 4
sequential IO: 19s
random IO: 83.92
-----------------------------------
fs.oss.multipart.download.ahead.part.max.number = 16
fs.oss.multipart.download.threads = 8
sequential IO: 13s
random IO: 50.561
Summaries:
* if read ahead part number = 1, sequential IO and random IO are the same since
there is no pre-fetch
* sequential IO will be better if read ahead part number and thread number
increases
* worst case of random IO will be something like [sequential ... sequential,
random, sequential ... sequential, random.....] so that some pre-fetch data
will be wasted.
> Improvements for Hadoop read from AliyunOSS
> -------------------------------------------
>
> Key: HADOOP-15027
> URL: https://issues.apache.org/jira/browse/HADOOP-15027
> Project: Hadoop Common
> Issue Type: Sub-task
> Components: fs/oss
> Affects Versions: 3.0.0
> Reporter: wujinhu
> Assignee: wujinhu
> Attachments: HADOOP-15027.001.patch, HADOOP-15027.002.patch,
> HADOOP-15027.003.patch
>
>
> Currently, read performance is poor when Hadoop reads from AliyunOSS. It
> needs about 1min to read 1GB from OSS.
> Class AliyunOSSInputStream uses single thread to read data from AliyunOSS,
> so we can refactor this by using multi-thread pre read to improve this.
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