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https://issues.apache.org/jira/browse/KAFKA-636?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13529222#comment-13529222
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Neha Narkhede commented on KAFKA-636:
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+1. Minor comments -
- Typos in the description of the deleteSegment API in Log.scala.
- I agree with Jun on the info log level for the delete messages.
> Make log segment delete asynchronous
> ------------------------------------
>
> Key: KAFKA-636
> URL: https://issues.apache.org/jira/browse/KAFKA-636
> Project: Kafka
> Issue Type: Bug
> Reporter: Jay Kreps
> Assignee: Jay Kreps
> Attachments: KAFKA-636-v1.patch
>
>
> We have a few corner-case bugs around delete of segment files:
> 1. It is possible for delete and truncate to kind of cross streams and end up
> with a case where you have no segments.
> 2. Reads on the log have no locking (which is good) but as a result deleting
> a segment that is being read will result in some kind of I/O exception.
> 3. We can't easily fix the synchronization problems without deleting files
> inside the log's write lock. This can be a problem as deleting a 2GB segment
> can take a couple of seconds even on an unloaded system.
> The proposed fix for these problems is to make file removal asynchronous
> using the following scheme as the new delete scheme:
> 1. Immediately remove the file from segment map and rename the~ file from X
> to X.deleted (e.g. 0000000.log to 000000.log.deleted. We think renaming a
> file will not impact reads since the file is already open and hence the name
> is irrelevant. This will always be O(1) and can be done inside the write lock.
> 2. Schedule a future operation to delete the file. The time to wait would be
> configurable but we would just default it to 60 seconds and probably no one
> would ever change it.
> 3. On startup we would delete any files with the .deleted suffix as they
> would have been pending deletes that didn't take place.
> I plan to do this soon working against the refactored log (KAFKA-521). We can
> opt to back port the patch for 0.8 if we are feeling daring.
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