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https://issues.apache.org/jira/browse/HADOOP-19233?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17927606#comment-17927606
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ASF GitHub Bot commented on HADOOP-19233:
-----------------------------------------
bhattmanish98 opened a new pull request, #7392:
URL: https://github.com/apache/hadoop/pull/7392
### Description of PR:
--------------------------------------------------------------------------------------------------------------------------------------------
This PR is in correlation to the series of work done under Parent Jira:
[[HADOOP-19179](https://issues.apache.org/jira/browse/HADOOP-19179)]
Jira for this Patch:
[[HADOOP-19233](https://issues.apache.org/jira/browse/HADOOP-19233)]
Currently, we only support rename and delete operations on the DFS endpoint.
The reason for not supporting rename and delete operations on the Blob endpoint
is that the Blob endpoint does not account for hierarchy. We need to ensure
that the HDFS contracts are maintained when performing rename and delete
operations. Renaming or deleting a directory over the Blob endpoint requires
the client to handle the orchestration and rename or delete all the blobs
within the specified directory.
The task outlines the considerations for implementing rename and delete
operations for the FNS-blob endpoint to ensure compatibility with HDFS
contracts.
- **Blob Endpoint Usage**: The task addresses the need for abstraction in
the code to maintain HDFS contracts while performing rename and delete
operations on the blob endpoint, which does not support hierarchy.
- **Rename Operations**: The AzureBlobFileSystem#rename() method will use a
RenameHandler instance to handle rename operations, with separate handlers for
the DFS and blob endpoints. This method includes prechecks, destination
adjustments, and orchestration of directory renaming for blobs.
- **Atomic Rename**: Atomic renaming is essential for blob endpoints, as it
requires orchestration to copy or delete each blob within the directory. A
configuration will allow developers to specify directories for atomic renaming,
with a JSON file to track the status of renames.
- **Delete Operations**: Delete operations are simpler than renames,
requiring fewer HDFS contract checks. For blob endpoints, the client must
handle orchestration, including managing orphaned directories created by
Az-copy.
- **Orchestration for Rename/Delete**: Orchestration for rename and delete
operations over blob endpoints involves listing blobs and performing actions on
each blob. The process must be optimized to handle large numbers of blobs
efficiently.
- **Need for Optimization**: Optimization is crucial because the ListBlob
API can return a maximum of 5000 blobs at once, necessitating multiple calls
for large directories. The task proposes a producer-consumer model to handle
blobs in parallel, thereby reducing processing time and memory usage.
- **Producer-Consumer Design**: The proposed design includes a producer to
list blobs, a queue to store the blobs, and a consumer to process them in
parallel. This approach aims to improve efficiency and mitigate memory issues.
> ABFS: [FnsOverBlob] Implementing Rename and Delete APIs over Blob Endpoint
> --------------------------------------------------------------------------
>
> Key: HADOOP-19233
> URL: https://issues.apache.org/jira/browse/HADOOP-19233
> Project: Hadoop Common
> Issue Type: Sub-task
> Components: fs/azure
> Affects Versions: 3.4.0
> Reporter: Anuj Modi
> Assignee: Manish Bhatt
> Priority: Major
> Labels: pull-request-available
>
> Currently, we only support rename and delete operations on the DFS endpoint.
> The reason for supporting rename and delete operations on the Blob endpoint
> is that the Blob endpoint does not account for hierarchy. We need to ensure
> that the HDFS contracts are maintained when performing rename and delete
> operations. Renaming or deleting a directory over the Blob endpoint requires
> the client to handle the orchestration and rename or delete all the blobs
> within the specified directory.
>
> The task outlines the considerations for implementing rename and delete
> operations for the FNS-blob endpoint to ensure compatibility with HDFS
> contracts.
> * {*}Blob Endpoint Usage{*}: The task addresses the need for abstraction in
> the code to maintain HDFS contracts while performing rename and delete
> operations on the blob endpoint, which does not support hierarchy.
> * {*}Rename Operations{*}: The {{AzureBlobFileSystem#rename()}} method will
> use a {{RenameHandler}} instance to handle rename operations, with separate
> handlers for the DFS and blob endpoints. This method includes prechecks,
> destination adjustments, and orchestration of directory renaming for blobs.
> * {*}Atomic Rename{*}: Atomic renaming is essential for blob endpoints, as
> it requires orchestration to copy or delete each blob within the directory. A
> configuration will allow developers to specify directories for atomic
> renaming, with a JSON file to track the status of renames.
> * {*}Delete Operations{*}: Delete operations are simpler than renames,
> requiring fewer HDFS contract checks. For blob endpoints, the client must
> handle orchestration, including managing orphaned directories created by
> Az-copy.
> * {*}Orchestration for Rename/Delete{*}: Orchestration for rename and delete
> operations over blob endpoints involves listing blobs and performing actions
> on each blob. The process must be optimized to handle large numbers of blobs
> efficiently.
> * {*}Need for Optimization{*}: Optimization is crucial because the
> {{ListBlob}} API can return a maximum of 5000 blobs at once, necessitating
> multiple calls for large directories. The task proposes a producer-consumer
> model to handle blobs in parallel, thereby reducing processing time and
> memory usage.
> * {*}Producer-Consumer Design{*}: The proposed design includes a producer to
> list blobs, a queue to store the blobs, and a consumer to process them in
> parallel. This approach aims to improve efficiency and mitigate memory issues.
> More details will follow
> Perquisites for this Patch:
> 1. HADOOP-19187 ABFS: [FnsOverBlob]Making AbfsClient Abstract for supporting
> both DFS and Blob Endpoint - ASF JIRA (apache.org)
> 2. HADOOP-19226 ABFS: [FnsOverBlob]Implementing Azure Rest APIs on Blob
> Endpoint for AbfsBlobClient - ASF JIRA (apache.org)
> 3. HADOOP-19207 ABFS: [FnsOverBlob]Response Handling of Blob Endpoint APIs
> and Metadata APIs - ASF JIRA (apache.org)
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