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https://issues.apache.org/jira/browse/APEXMALHAR-2063?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15391174#comment-15391174
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ASF GitHub Bot commented on APEXMALHAR-2063:
--------------------------------------------
Github user chandnisingh commented on a diff in the pull request:
https://github.com/apache/apex-malhar/pull/322#discussion_r71995534
--- Diff:
library/src/main/java/org/apache/apex/malhar/lib/wal/WindowDataManager.java ---
@@ -126,36 +146,24 @@ public void teardown()
}
@Override
- public void save(Object object, int operatorId, long windowId) throws
IOException
+ public void save(Object object, long windowId) throws IOException
{
}
@Override
- public Object load(int operatorId, long windowId) throws IOException
+ public Object retrieve(long windowId) throws IOException
{
return null;
}
@Override
- public void delete(int operatorId, long windowId) throws IOException
- {
- }
-
- @Override
- public void deleteUpTo(int operatorId, long windowId) throws
IOException
--- End diff --
changed the method to be committed(long windowId). WindowDataManager is
Evolving so this was ok.
> Integrate WAL to FS WindowDataManager
> -------------------------------------
>
> Key: APEXMALHAR-2063
> URL: https://issues.apache.org/jira/browse/APEXMALHAR-2063
> Project: Apache Apex Malhar
> Issue Type: Improvement
> Reporter: Chandni Singh
> Assignee: Chandni Singh
>
> FS Window Data Manager is used to save meta-data that helps in replaying
> tuples every completed application window after failure. For this it saves
> meta-data in a file per window. Having multiple small size files on hdfs
> cause issues as highlighted here:
> http://blog.cloudera.com/blog/2009/02/the-small-files-problem/
> Instead FS Window Data Manager can utilize the WAL to write data and maintain
> a mapping of how much data was flushed to WAL each window.
> In order to use FileSystemWAL for replaying data of a finished window, there
> are few changes made to FileSystemWAL this is because of following:
> 1. WindowDataManager needs to reply data of every finished window. This
> window may not be checkpointed.
> FileSystemWAL truncates the WAL file to the checkpointed point after recovery
> so this poses a problem.
> WindowDataManager should be able to control recovery of FileSystemWAL.
> 2. FileSystemWAL writes to temporary files. The mapping of temp files to
> actual file is part of its state which is checkpointed. Since
> WindowDataManager replays data of a window not yet checkpointed, it needs to
> know the actual temporary file the data is being persisted to.
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