Tuesday, February 27, 2007

[off topic] message logging severities

I can recall only five levels of severities:

MAJOR: Alarm. Critical unrecoverable error. Results in certain termination of application.
MINOR: Recoverable error. Application can go on, but something is fishy.
NOTICE: Not an error, but shouldn't have happened.
INFO: Run-time information statistics, "anomalies" a.k.a. unsolicited messages. Must produce passable amount of information since might be used for monitoring of real system.
TRACE: Used to trace what's happening in the system: functions called and their arguments. Produces insane amount of output.
DEBUG: Debugging info. Developer's corner.

Production systems run on MINOR level, so that all errors are displayed. MAJOR level normally has abort() built in so that OS would dump core of application for further investigations.

Systems in testing run with INFO level. Often the output is saved and required to match in repeated tests. E.g. if we have fed application with 1000 bytes of info, we would expect INFO message to reflect that 1000 bytes where handled. Not 999, not 1001, not 500 + 500.

Edit1: Added "TRACE" level.

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