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Sylvain Lebresne commented on CASSANDRA-3430:
---------------------------------------------
bq. Hmm. That's true, but that also makes it more obvious that we could
potentially have data flushed post-"main" truncate, whose indexes get
truncated, so the index won't actually match the data file. Right?
I think the current truncate is already racy. Because we flush and grab the
truncateAt timestamp outside of the compaction lock. So it is possible that
between the grab of truncateAt and the beginning of submitTruncate, some new
sstable is flushed and compacted against "pre-truncate" sstables (and since our
compaction lock is not fair, it's not even an absolutely crazy scenario), which
would lead on the data on sstable not being removed (which can lead to having
bad indexes already since this can happen for an index cf only).
I don't really think this ticket makes this problem worst, nor does it fixes
it. And grabbing the baseCF lock along with the indexes ones wouldn't fix it
either. I think what we must do is lock everything before we even start doing
the flush and grabbing of truncateAt.
But in any case, if we don't grab the index CF lock while calling markCompacted
on that cf, we have a risk of segfaulting the VM (if it happens we're deleting
a sstable that is being compacted). In other word, I would be fine with
committing this ticket with the lock grabbing pushed inside the for loop as of
my initial comment on the argument that 'potentially have some data not
truncated as it should' is already an existing bug (and defer it's resolution
to another ticket), but I'm -1 on introducing the possibility of a JVM segfault.
> Break Big Compaction Lock apart
> -------------------------------
>
> Key: CASSANDRA-3430
> URL: https://issues.apache.org/jira/browse/CASSANDRA-3430
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Reporter: Jonathan Ellis
> Assignee: Jonathan Ellis
> Priority: Minor
> Labels: compaction
> Fix For: 1.0.3
>
> Attachments: 3430-1.0.txt, 3430-1.1.txt
>
>
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