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https://issues.apache.org/jira/browse/CASSANDRA-36?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12697825#action_12697825
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Jonathan Ellis commented on CASSANDRA-36:
-----------------------------------------
The hadoop guys are right; a pull interface (allowing the stats aggregator to
request via http for example) is better than push (writing to logs and making
the aggregator parse them out).
> Log runtime stats for analysis by ops
> -------------------------------------
>
> Key: CASSANDRA-36
> URL: https://issues.apache.org/jira/browse/CASSANDRA-36
> Project: Cassandra
> Issue Type: Improvement
> Reporter: Jonathan Ellis
> Fix For: 0.4
>
>
> We need to log stats that indicate node / cluster health. Some that I can
> think of are:
> - executor pool pending operation (queue) length [memtable per CF,
> memtablemanager, storageservice.bootstraper,
> storageservice.consistencymanager]
> - memtable size (which is more useful: per CF or total?)
> - sstable size, per CF
> - number of unmerged SSTables, per CF
> - size of sstable indexes (this is the other major semi-permanent memory
> chunk)
> - writes, reads per second (throughput)
> - average seconds per write / read (latency)
> - percent of reads that have to hit a SSTable (we don't know if this is in
> the OS cache or not, so is this actually useful?)
> - commitlog on-disk size (want to make sure these are getting cleaned out
> regularly)
> Currently some of these are logged in an ad-hoc manner, e.g. time to read in
> ReadVerbHandler, but aggregation is not done and logs on a per-op basis are
> going to get quite spammy. I'd like one thread to be in charge of logging,
> to dump aggregate data (at level INFO) every minute or so.
> Might also be nice to expose this on the web console.
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