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https://issues.apache.org/jira/browse/CASSANDRA-10241?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14726197#comment-14726197
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Ariel Weisberg commented on CASSANDRA-10241:
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My goal with this suggestion is to eliminate the conflicting priorities of user
visible human readable logging and more verbose less readable debug/trace
logging. We can't eliminate the overhead of trace logging so we can't log
everything. Statements that execute one per operation or per record and
statements that dump large data structures aren't good candidates.
Once you can be chatty in the log you can start logging state transitions that
you almost never care about, but are helpful when the unexpected happens. Over
time you can start to accrue more useful logging as you work through real
failures.
We also really need go/no go measurements for what is logged via this mechanism
so we know what it is costing us. Maybe a JMX metric that reports on the log
throughput, statements/second, bytes/second with some historical window so we
can diagnose issues related to poorly designed logging. Or we can just be
careful.
bq. Related: is it time to switch to AsyncAppender?
One thing you can do with AsyncAppending is have error and warn log
synchronously so you get a stronger guarantee errors are visible (such as
before voluntarily terminating). That somewhat mitigates the risk of missing
important messages.
I think that switching to async appending is less critical in C* because it
doesn't have a thread per core design. If there are places we log while holding
locks, well that's a different story. As long as the thread doing the logging
is the only one impacted and we don't have a design where for whatever reason
we have some special threads everyone may end up waiting on then it is fine.
Put another way it's 4th or 5th nine issue.
> Keep a separate production debug log for troubleshooting
> --------------------------------------------------------
>
> Key: CASSANDRA-10241
> URL: https://issues.apache.org/jira/browse/CASSANDRA-10241
> Project: Cassandra
> Issue Type: Bug
> Components: Config
> Reporter: Jonathan Ellis
> Assignee: Brandon Williams
> Fix For: 2.1.x
>
>
> [~aweisberg] had the suggestion to keep a separate debug log for aid in
> troubleshooting, not intended for regular human consumption but where we can
> log things that might help if something goes wrong.
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