Genmao Yu commented on HADOOP-14999:

cc [~ste...@apache.org]

> 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´╝Ü
>  - 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.
> 3. Each task will retry 3 times to upload block to Aliyun OSS. If one of 
> those tasks failed, the whole file uploading will failed, and we will abort 
> current uploading.

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