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https://issues.apache.org/jira/browse/CASSANDRA-10979?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15088274#comment-15088274
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Sebastian Estevez edited comment on CASSANDRA-10979 at 1/7/16 10:34 PM:
[~krummas] I mentioned this briefly this morning over chat but now we have more
information. Specifically we observe a large L0 to L1 compaction that blocks
additional L0 STCS compactions, probably because the remaining L0 sstables
overlap compactingL0.
You can see in the log above that {quote}L0 is too far behind, performing
size-tiering there first{quote} does not appear. What do you think?
was (Author: sebastian.este...@datastax.com):
[~krummas] I mentioned this briefly this morning over chat but now we have more
information specifically we observe a large L0 to L1 compaction that blocks L0
STCS compactions, probably because the remaining L0 sstables overlap
compactingL0. You can see in the log above that {quote}L0 is too far behind,
performing size-tiering there first{quote} does not appear. What do you think?
> LCS doesn't do L0 STC on new tables while an L0->L1 compaction is in progress
> -
>
> Key: CASSANDRA-10979
> URL: https://issues.apache.org/jira/browse/CASSANDRA-10979
> Project: Cassandra
> Issue Type: Bug
> Components: Compaction
> Environment: 2.1.11 / 4.8.3 DSE.
>Reporter: Jeff Ferland
> Labels: compaction, leveled
> Fix For: 2.1.x
>
>
> Reading code from
> https://github.com/apache/cassandra/blob/cassandra-2.1/src/java/org/apache/cassandra/db/compaction/LeveledManifest.java
> and comparing with behavior shown in
> https://gist.github.com/autocracy/c95aca6b00e42215daaf, the following happens:
> Score for L1,L2,and L3 is all < 1 (paste shows 20/10 and 200/100, due to
> incremental repair).
> Relevant code from here is
> if (Sets.intersection(l1overlapping, compacting).size() > 0)
> return Collections.emptyList();
> Since there will be overlap between what is compacting and L1 (in my case,
> pushing over 1,000 tables in to L1 from L0 SCTS), I get a pile up of 1,000
> smaller tables in L0 while awaiting the transition from L0 to L1 and destroy
> my performance.
> Requested outcome is to continue to perform SCTS on non-compacting L0 tables.
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