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From "Jose Fernandez (JIRA)" <j...@apache.org>
Subject [jira] [Comment Edited] (CASSANDRA-11209) SSTable ancestor leaked reference
Date Mon, 22 Feb 2016 21:51:18 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-11209?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15157768#comment-15157768
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Jose Fernandez edited comment on CASSANDRA-11209 at 2/22/16 9:50 PM:
---------------------------------------------------------------------

Another scenario of this "bug" is that both Live and Used are in sync, but the actual size
of files in disk is not. Once the node is restarted (indicated by an arrow in the screenshot),
everything syncs up.

This leads me to believe that something is not correctly registering new sstables (maybe during
repair?).

 !screenshot-1.png!


was (Author: jrfernandez):
Another scenario of this "bug" is that both Live and Used -are- in sync, but the actual size
of files in disk is not. Once the node is restarted (indicated by an arrow in the screenshot),
everything syncs up.

This leads me to believe that something is not correctly registering new sstables (maybe during
repair?).

 !screenshot-1.png!

> SSTable ancestor leaked reference
> ---------------------------------
>
>                 Key: CASSANDRA-11209
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-11209
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Compaction
>            Reporter: Jose Fernandez
>         Attachments: screenshot-1.png
>
>
> We're running a fork of 2.1.13 that adds the TimeWindowCompactionStrategy from [~jjirsa].
We've been running 4 clusters without any issues for many months until a few weeks ago we
started scheduling incremental repairs every 24 hours (previously we didn't run any repairs
at all).
> Since then we started noticing big discrepancies in the LiveDiskSpaceUsed, TotalDiskSpaceUsed,
and actual size of files on disk. The numbers are brought back in sync by restarting the node.
We also noticed that when this bug happens there are several ancestors that don't get cleaned
up. A restart will queue up a lot of compactions that slowly eat away the ancestors.
> I looked at the code and noticed that we only decrease the LiveTotalDiskUsed metric in
the SSTableDeletingTask. Since we have no errors being logged, I'm assuming that for some
reason this task is not getting queued up. If I understand correctly this only happens when
the reference count for the SStable reaches 0. So this is leading us to believe that something
during repairs and/or compactions is causing a reference leak to the ancestor table.



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