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From "Benedict (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (CASSANDRA-7000) Assertion in SSTableReader during repair.
Date Thu, 10 Apr 2014 20:38:17 GMT

     [ https://issues.apache.org/jira/browse/CASSANDRA-7000?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Benedict updated CASSANDRA-7000:
--------------------------------

    Attachment: 7000.supplement.txt

Not sure if we want to tack this onto the same ticket, but the same basic problem seems to
occur elsewhere as well: some referrers of sstablereader do not acquire a reference prior
to accessing resources that will be closed when ref count hits zero. I found specifically
CFS.estimatedKeysForRange, CFS.keySamples, couldn't see any others.

This latter is the cause of the currently failing unit test for 2.1

> Assertion in SSTableReader during repair.
> -----------------------------------------
>
>                 Key: CASSANDRA-7000
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-7000
>             Project: Cassandra
>          Issue Type: Bug
>            Reporter: Ben Chan
>            Assignee: Ben Chan
>         Attachments: 7000-2.1-v2.txt, 7000.supplement.txt, sstablereader-assertion-bisect-helper,
sstablereader-assertion-bisect-helper-v2, sstablereader-assertion.patch
>
>
> I ran a {{git bisect run}} using the attached bisect script. Repro code:
> {noformat}
> # 5dfe241: trunk as of my git bisect run
> # 345772d: empirically determined "good" commit.
> git bisect start 5dfe241 345772d
> git bisect run ./sstablereader-assertion-bisect-helper-v2
> {noformat}
> The first failing commit is 5ebadc1 (first parent of {{refs/bisect/bad}}).
> Prior to 5ebadc1, SSTableReader#close() never checked reference count. After 5ebadc1,
there was an assertion for {{references.get() == 0}}. However, since the reference count is
initialized to 1, a SSTableReader#close() was always guaranteed to either throw an AssertionError
or to be a second call to SSTableReader#tidy() on the same SSTableReader.
> The attached patch chooses an in-between behavior. It requires the reference count to
match the initialization value of 1 for SSTableReader#close(), and the same behavior as 5ebadc1
otherwise.
> This allows repair to finish successfully, but I'm not 100% certain what the desired
behavior is for SSTableReader#close(). Should it close without regard to reference count,
as it did pre-5ebadc1?
> Edit: accidentally uploaded a flawed version of {{sstablereader-assertion-bisect-helper}}
(doesn't work out-of-the-box with {{git bisect}}).



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