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https://issues.apache.org/jira/browse/SOLR-11934?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16464824#comment-16464824
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Shawn Heisey commented on SOLR-11934:
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[~erickerickson], I like your ideas.
The query logging is also a significant contributor, *especially* on sharded
indexes. SOLR-11453 got me thinking in the background about the possibility of
sending query (technically, actually request, which includes query) logs to
their own file as well.
Updates do result in particularly verbose and numerous logs. I wonder if
there's any value to extending the 'separate logfile' paradigm for the detailed
information, with the summary info you suggested in the main log.
The only disadvantage I can think of with separate logfiles for primary logging
events, and the main notion that makes me *slightly* resistant to making that
config default, is that it is very difficult to reconstruct a narrative of
events that are logged at the same millisecond in those separate files. If
they're all in the same file, it's usually very easy to determine the order of
events. If we do make separate request/update logs a default config, the
documentation must explain how to turn those separate logs off. That would be
vital to troubleshooting issues that only show up under heavy load.
> Visit Solr logging, it's too noisy.
> -----------------------------------
>
> Key: SOLR-11934
> URL: https://issues.apache.org/jira/browse/SOLR-11934
> Project: Solr
> Issue Type: Improvement
> Security Level: Public(Default Security Level. Issues are Public)
> Reporter: Erick Erickson
> Assignee: Erick Erickson
> Priority: Major
>
> I think we have way too much INFO level logging. Or, perhaps more correctly,
> Solr logging needs to be examined and messages logged at an appropriate level.
> We log every update at an INFO level for instance. But I think we log LIR at
> INFO as well. As a sysadmin I don't care to have my logs polluted with a
> message for every update, but if I'm trying to keep my system healthy I want
> to see LIR messages and try to understand why.
> Plus, in large installations logging at INFO level is creating a _LOT_ of
> files.
> What I want to discuss on this JIRA is
> 1> What kinds of messages do we want log at WARN, INFO, DEBUG, and TRACE
> levels?
> 2> Who's the audience at each level? For a running system that's functioning,
> sysops folks would really like WARN messages that mean something need
> attention for instance. If I'm troubleshooting should I turn on INFO? DEBUG?
> TRACE?
> So let's say we get some kind of agreement as to the above. Then I propose
> three things
> 1> Someone (and probably me but all help gratefully accepted) needs to go
> through our logging and assign appropriate levels. This will take quite a
> while, I intend to work on it in small chunks.
> 2> Actually answer whether unnecessary objects are created when something
> like log.info("whatever {}", someObjectOrMethodCall); is invoked. Is this
> independent on the logging implementation used? The SLF4J and log4j seem a
> bit contradictory.
> 3> Maybe regularize log, logger, LOG as variable names, but that's a nit.
> As a tactical approach, I suggest we tag each LoggerFactory.getLogger in
> files we work on with //SOLR-(whatever number is assigned when I create
> this). We can remove them all later, but since I expect to approach this
> piecemeal it'd be nice to keep track of which files have been done already.
> Finally, I really really really don't want to do this all at once. There are
> 5-6 thousand log messages. Even at 1,000 a week that's 6 weeks, even starting
> now it would probably span the 7.3 release.
> This will probably be an umbrella issue so we can keep all the commits
> straight and people can volunteer to "fix the files in core" as a separate
> piece of work (hint).
> There are several existing JIRAs about logging in general, let's link them in
> here as well.
> Let the discussion begin!
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