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https://issues.apache.org/jira/browse/CASSANDRA-17440?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17506923#comment-17506923
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Paulo Motta commented on CASSANDRA-17440:
-----------------------------------------
I think the best place to implement this is in
[ActiveCompactions|https://github.com/apache/cassandra/blob/bf96367f4d55692017e144980cf17963e31df127/src/java/org/apache/cassandra/db/compaction/ActiveCompactions.java].
Instead of updating compaction progress [only at the
end|https://github.com/apache/cassandra/blob/bf96367f4d55692017e144980cf17963e31df127/src/java/org/apache/cassandra/db/compaction/ActiveCompactions.java#L48],
we would schedule a periodic reporter task for each active compaction and stop
the task when compaction is completed.
Something along these lines:
{code:java}
class ActiveCompactions {
void beginCompactions(CompactionInfo.Holder ci)
{
future = schedule(() -> reportInfo(ci),
getProperty("cassandra.compacted_bytes_reporter_period", 1), TimeUnit.MINUTES)
}
void reportInfo(CompactionInfo.Holder ci)
{
CompactionInfo info = ci.getCompactionInfo();
long compactedBytes = computeDelta(info);
CompactionManager.instance.getMetrics().bytesCompacted.inc(compactedBytes);
}
void endCompaction(CompactionInfo.Holder ci)
{
reportInfo(ci):
future.cancel();
}
}
{code}
Please let me know what do you think of this approach.
> Report compacted bytes metric periodically
> ------------------------------------------
>
> Key: CASSANDRA-17440
> URL: https://issues.apache.org/jira/browse/CASSANDRA-17440
> Project: Cassandra
> Issue Type: Improvement
> Components: Local/Compaction
> Reporter: Paulo Motta
> Priority: Normal
>
> Currently the compacted bytes metrics are incremented only at the end of the
> compaction, which can take a long time to update for long running compactions.
> We should periodically (ie. every 1 minute, configurable) update the
> compacted bytes metric to improve compaction throughput observability.
> This is issue is analogous of CASSANDRA-16325 but for compaction instead of
> streaming.
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