Log4Perl configuration problems

ribasushi has asked for the wisdom of the Perl Monks concerning the following question:

Greetings honorable Monks,

Since the documentation for log4perl sucks massively, I am coming here for advice. Here are my problems:

Depending on the tutorial used one can see log4perl.logger or log4perl.root or log4perl.rootLogger as the name of the top hierarchy logger. This is very confusing - are they aliases to the same thing? Or are they tied in some sort of hierarchy? What is the significance of the text after the dot? (obviously not a category name - there is category.x for that)

How can one do the following (non-working example):
```
log4perl.logger = INFO, Screen
log4perl.logger = DEBUG, DBGFile
...
[download]
```
with the obvious intention to log to several places, filtering based only on log level

Are category.x and logger.x completely different subsystems, or do they actually have some inheritance/relationship between them?

Any references to reading material are appreciated - all I could google were quick-start tutorials without much in-depth architecture explanation. I tried to read the source as well, but gave up at the init() stage.

Thanks!

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Re: Log4Perl configuration problems by andreas1234567 (Vicar) on Jun 13, 2008 at 11:46 UTC
the documentation for log4perl sucks massively That's both harsh and completely unfair. In fact, I think the Log::Log4perl documentation is both extensive and well written. Courtesy never hurts, and sometimes helps. 2. How can one do the following (non-working example): You can log both to screen (stderr) and a rotating file like this: use Log::Log4perl; use Log::Dispatch::FileRotate; my $conf = undef; my $log = undef; my $help = undef; my $test = undef; my $file = undef; $conf = q( log4perl.category.Script = INFO, ScreenAppender, ScriptFile +RotateAppender log4perl.appender.ScreenAppender = Log::Log4perl::Appender:: +Screen log4perl.appender.ScreenAppender.stderr = 1 log4perl.appender.ScreenAppender.layout = PatternLayout log4perl.appender.ScreenAppender.layout.ConversionPattern=[%p] %d %F +:%L - %m%n log4perl.appender.ScreenAppender.Threshold = DEBUG log4perl.appender.ScriptFileRotateAppender = Log::Dispatch +::FileRotate log4perl.appender.ScriptFileRotateAppender.filename = script.log log4perl.appender.ScriptFileRotateAppender.mode = append log4perl.appender.ScriptFileRotateAppender.size = 100000 log4perl.appender.ScriptFileRotateAppender.max = 5 log4perl.appender.ScriptFileRotateAppender.layout = PatternLayout log4perl.appender.ScriptFileRotateAppender.layout.ConversionPattern= +[%p] %d %F:%L: %m%n ); Log::Log4perl::init( \$conf ); $log = Log::Log4perl::->get_logger(q(Script)); $log->debug("start") if $log->is_debug(); $log->warn("stop") if $log->is_warn(); [download] -- No matter how great and destructive your problems may seem now, remember, you've probably only seen the tip of them. [1]	[reply] [d/l]
Re^2: Log4Perl configuration problems by ribasushi (Pilgrim) on Jun 13, 2008 at 11:58 UTC
That's both harsh and completely unfair. In fact, I think the Log::Log4perl documentation is both extensive and well written. Courtesy never hurts, and sometimes helps. I am happy you feel this way about the massively incomplete documentation. Just to prove my point - tell me where in the docs is .Threshold being discussed? Certainly not in Log::Log4perl, nor in Log::Log4perl::Config (the only two places where a seasoned CPAN user would look). The only place I found this modifier (after your hint) was in the FAQ, and even then - it was in sections completely unrelated to my problem. Thank you, nevertheless, for pointing me in the right direction. I stand by my words however.	[reply]
Re^3: Log4Perl configuration problems by andreas1234567 (Vicar) on Jun 13, 2008 at 12:58 UTC
The References section has a link to an article that complements the documentation well. It says (on page 3): Each appender can define a so-called appender threshold, a minimum level required for an oncoming message to be honored by the appender: `$appender->threshold($ERROR);` [download] If the level doesn't meet the appender's threshold, then it is simply ignored by this appender. Was that what you were looking for? -- No matter how great and destructive your problems may seem now, remember, you've probably only seen the tip of them. [1]	[reply] [d/l]
Re^3: Log4Perl configuration problems by Anonymous Monk on Jun 14, 2008 at 07:48 UTC
You don't stand alone friend, but you're letting your frustrations get the better of you. Just to prove my point - tell me where in the docs is .Threshold being discussed? Certainly not in Log::Log4perl, nor in Log::Log4perl::Config (the only two places where a seasoned CPAN user would look). The only place I found this modifier (after your hint) was in the FAQ, and even then - it was in sections completely unrelated to my problem. http://search.cpan.org/grep?cpanid=MSCHILLI&release=Log-Log4perl-1.16&string=Threshold&i=1&n=1&C=0 http://search.cpan.org/~mschilli/Log-Log4perl-1.16/lib/Log/Log4perl.pm#Modify_appender_thresholds http://search.cpan.org/~mschilli/Log-Log4perl-1.16/lib/Log/Log4perl.pm##System-wide_log_levels System-wide log levels As a fairly drastic measure to decrease (or increase) the logging level all over the system with one single configuration option, use the `threshold` keyword in the Log4perl configuration file: `log4perl.threshold = ERROR` sets the system-wide (or hierarchy-wide according to the log4j documentation) to ERROR and therefore deprives every logger in the system of the right to log lower-prio messages. I would start at the beginning, makes the learning curve less steep.	[reply] [d/l] [select]
Re: Log4Perl configuration problems by Anonymous Monk on Jun 13, 2008 at 13:36 UTC
As a sidenote here, if you think a given distribution has lousy docs, and you have any choice in the matter, you should probably email the maintainer (with constructive criticism) and then not use said module if there's no improvement. Silently using modules with bad docs sends the message that docs don't matter because you'll use the software anyway.	[reply]
Re^2: Log4Perl configuration problems by ribasushi (Pilgrim) on Jun 13, 2008 at 13:44 UTC
Generally you are correct, however this module is ahead of the crowd by leaps and bounds. The design is too good to pass on it over documentation issues. It's like saying "I won't use IO::Socket because the docs suck".	[reply]

System-wide log levels