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https://issues.apache.org/jira/browse/CASSANDRA-3269?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13119171#comment-13119171
]
Yang Yang commented on CASSANDRA-3269:
--------------------------------------
I think I found why:
CommitLogSegment.turnOffIfNotWritten() :
void turnOffIfNotWritten(Integer cfId, Integer flushPosition)
{
Integer lastWritten = cfLastWrite.get(cfId);
if (lastWritten == null || lastWritten < flushPosition)
cfLastWrite.remove(cfId);
}
the comparison "<" probably should be "<="
let's say we flush a Memtable, and we have only 1 commitlogsegment in system
now. after the flush, no write has come in, now the post-flush job tries to
discard segments,
the context passed in points to the current pointer, which is the same as
cfLastWrite,
then the comparison fails here, and the bit in this logsegment is not removed.
later, either the cf is never flushed, or when it is being forcefully flushed,
we find that there is no new writes to the CF, so the CF isclean(), so the
flush is never submitted, and the post-flush can never be run, so the dirty bit
can never be cleared.....
sounds right?
> accumulated 100GB of commit logs
> --------------------------------
>
> Key: CASSANDRA-3269
> URL: https://issues.apache.org/jira/browse/CASSANDRA-3269
> Project: Cassandra
> Issue Type: Bug
> Affects Versions: 1.0.0
> Reporter: Yang Yang
>
> I ran my cluster for about 2 days. the cluster has 2 nodes. I restarted one
> box several times, and the other one was always running. the one always
> running ended up accumulating 100GB of commit logs.
> this is 1.0.0 code from about Sept 15 in github. I kept the original setting
> for
> #commitlog_total_space_in_mb: 4096
> i.e. commented out
> here is some sample of the output:
> -rw-r--r-- 1 yyang yyang 134217857 2011-09-28 03:51
> CommitLog-1317181834810.log
> -rw-r--r-- 1 yyang yyang 134217869 2011-09-28 03:50
> CommitLog-1317181764105.log
> -rw-r--r-- 1 yyang yyang 134217783 2011-09-28 03:49
> CommitLog-1317181694633.log
> -rw-r--r-- 1 yyang yyang 134217750 2011-09-28 02:39
> CommitLog-1317176955102.log
> yyang@ip-10-71-21-46:/mnt/cass/log/cassandra$ ls -lt
> /mnt/cass/lib//cassandra/commitlog/|wc -l
> 727
> yyang@ip-10-71-21-46:/mnt/cass/log/cassandra$ du -s
> /mnt/cass/lib/cassandra/commitlog/
> 95095316 /mnt/cass/lib/cassandra/commitlog/
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