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https://issues.apache.org/jira/browse/HADOOP-14999?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16338785#comment-16338785
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Genmao Yu commented on HADOOP-14999:
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cc [~Sammi], take a review please
> AliyunOSS: provide one asynchronous multi-part based uploading mechanism
> ------------------------------------------------------------------------
>
> Key: HADOOP-14999
> URL: https://issues.apache.org/jira/browse/HADOOP-14999
> Project: Hadoop Common
> Issue Type: Sub-task
> Components: fs/oss
> Affects Versions: 3.0.0-beta1
> Reporter: Genmao Yu
> Assignee: Genmao Yu
> Priority: Major
> Attachments: HADOOP-14999.001.patch, HADOOP-14999.002.patch,
> HADOOP-14999.003.patch, HADOOP-14999.004.patch, HADOOP-14999.005.patch,
> HADOOP-14999.006.patch, HADOOP-14999.007.patch,
> asynchronous_file_uploading.pdf
>
>
> This mechanism is designed for uploading file in parallel and asynchronously:
> - improve the performance of uploading file to OSS server. Firstly, this
> mechanism splits result to multiple small blocks and upload them in parallel.
> Then, getting result and uploading blocks are asynchronous.
> - avoid buffering too large result into local disk. To cite an extreme
> example, there is a task which will output 100GB or even larger, we may need
> to output this 100GB to local disk and then upload it. Sometimes, it is
> inefficient and limited to disk space.
> This patch reuse {{SemaphoredDelegatingExecutor}} as executor service and
> depends on HADOOP-15039.
> Attached {{asynchronous_file_uploading.pdf}} illustrated the difference
> between previous {{AliyunOSSOutputStream}} and
> {{AliyunOSSBlockOutputStream}}, i.e. this asynchronous multi-part based
> uploading mechanism.
> 1. {{AliyunOSSOutputStream}}: we need to output the whole result to local
> disk before we can upload it to OSS. This will poses two problems：
> - if the output file is too large, it will run out of the local disk.
> - if the output file is too large, task will wait long time to upload
> result to OSS before finish, wasting much compute resource.
> 2. {{AliyunOSSBlockOutputStream}}: we cut the task output into small blocks,
> i.e. some small local file, and each block will be packaged into a uploading
> task. These tasks will be submitted into {{SemaphoredDelegatingExecutor}}.
> {{SemaphoredDelegatingExecutor}} will upload this blocks in parallel, this
> will improve performance greatly.
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