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https://issues.apache.org/jira/browse/CASSANDRA-36?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12694581#action_12694581
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Jonathan Ellis commented on CASSANDRA-36:
-----------------------------------------

Todd points out https://issues.apache.org/jira/browse/HADOOP-5469.

Can we just log a huge json object with log4j, or are per-log-message size 
limits going to bite?

> 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
>
> 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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