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https://issues.apache.org/jira/browse/STORM-876?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15015088#comment-15015088
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ASF GitHub Bot commented on STORM-876:
--------------------------------------
Github user d2r commented on the pull request:
https://github.com/apache/storm/pull/845#issuecomment-158264627
```
396 struct ReadableBlobMeta {
397 1: required SettableBlobMeta settable;
398 //This is some indication of a version of a BLOB. The only guarantee
is
399 // if the data changed in the blob the version will be different.
400 2: required i64 version;
401 }
```
Since the code now deals with more than one nimbus daemon, is it still true
that there are no other guarantees?
Can a blob be updated such that its version equals a previous version's
value? Is there ordering to blob versions?
> Dist Cache: Basic Functionality
> -------------------------------
>
> Key: STORM-876
> URL: https://issues.apache.org/jira/browse/STORM-876
> Project: Apache Storm
> Issue Type: Improvement
> Components: storm-core
> Reporter: Robert Joseph Evans
> Assignee: Robert Joseph Evans
> Attachments: DISTCACHE.md, DistributedCacheDesignDocument.pdf
>
>
> Basic functionality for the Dist Cache feature.
> As part of this a new API should be added to support uploading and
> downloading dist cache items. storm-core.ser, storm-conf.ser and storm.jar
> should be written into the blob store instead of residing locally. We need a
> default implementation of the blob store that does essentially what nimbus
> currently does and does not need anything extra. But having an HDFS backend
> too would be great for scalability and HA.
> The supervisor should provide a way to download and manage these blobs and
> provide a working directory for the worker process with symlinks to the
> blobs. It should also allow the blobs to be updated and switch the symlink
> atomically to point to the new blob once it is downloaded.
> All of this is already done by code internal to Yahoo! we are in the process
> of getting it ready to push back to open source shortly.
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