Logging on 2.2 and beyond

[Paulo Motta <pa...@gmail.com>]

Hello,

CASSANDRA-10241 introduced a new log file appender to Cassandra 2.2+,
debug.log, in addition to the traditional system.log which we're used to.
The idea is to move verbose information to debug.log (at DEBUG level), and
keep more high level INFO node/cluster status messages (in addition to
ERRORs and WARNs) on system.log.

We should still avoid adding verbose logs to the critical path in order not
to risk affecting performance, but we should be encouraged to add more
descriptive DEBUG messages to operations on non-critical paths in order to
aid in troubleshooting, improve operator's well-being and help JIRA bug
fillings. The TRACE level will be disabled by default and should be used
for development or special purposes.

I invite all the developers to have a look and contribute suggestions to
the logging guidelines proposal I put on the wiki (
https://wiki.apache.org/cassandra/LoggingGuidelines), as well as have a
look and participate on the discussion on
https://issues.apache.org/jira/browse/CASSANDRA-10241.

Thanks,

Paulo