Confused about log4j.properties

[Kawthar Bt M Sulaiman]

Hi,

In this file, there's:

log4j.rootCategory=debug, MO ----> <first>

Then,

log4j.appender.MO=org.apache.log4j.DailyRollingFileAppender
log4j.appender.MO.Threshold=DEBUG. -----> <second>
...

My question, is the debug <on first> and <debug on second> has the
same
meaning? So, if I just want to log INFO and above, do I change the
Threashold=INFO only or both?

I was looking for a documentation on what each lines mean but
couldn't find it.

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[Simon Kitching]

Post by Kawthar Bt M Sulaiman
Hi,
log4j.rootCategory=debug, MO ----> <first>
Then,
log4j.appender.MO=org.apache.log4j.DailyRollingFileAppender
log4j.appender.MO.Threshold=DEBUG. -----> <second>
...
My question, is the debug <on first> and <debug on second> has the
same
meaning? So, if I just want to log INFO and above, do I change the
Threashold=INFO only or both?

When some code logs a message, it specifies a priority and a category.
If the message priority is less than the category priority, then the
message is totally ignored.

Once the message gets past that first cutoff, some significant work gets
done (creating a LogEvent object etc), then the message is sent on to
each appender (ie "outputter") associated with the category.

If any of those appenders has a threshold set, then that appender
discards (ignores) the message if its priority is less than the
threshold.

So this allows you to say:
* category X has two appenders: file and email
* for category X, ignore everything lower than INFO
* for the file appender, accept all that pass the category priority
(ie no threshold set)
* for the email appender, ignore those messages which got past the
category filtering, but are lower than WARN

It is more efficient to filter at the category level than the appender
level, but if you want different amounts of detail written to different
appenders for the same category, then the threshold setting allows you
to do this.

Cheers,

Simon

[Kawthar Bt M Sulaiman]

Oh ok.... now I understand.

Thank you.
--Kawthar

Post by Kawthar Bt M Sulaiman
Hi,
log4j.rootCategory=debug, MO ----> <first>
Then,
log4j.appender.MO=org.apache.log4j.DailyRollingFileAppender
log4j.appender.MO.Threshold=DEBUG. -----> <second>
...
My question, is the debug <on first> and <debug on second> has the
same
meaning? So, if I just want to log INFO and above, do I change the
Threashold=INFO only or both?

When some code logs a message, it specifies a priority and a category.
If the message priority is less than the category priority, then the
message is totally ignored.

Once the message gets past that first cutoff, some significant work
gets
done (creating a LogEvent object etc), then the message is sent on to
each appender (ie "outputter") associated with the category.

If any of those appenders has a threshold set, then that appender
discards (ignores) the message if its priority is less than the
threshold.

So this allows you to say:
* category X has two appenders: file and email
* for category X, ignore everything lower than INFO
* for the file appender, accept all that pass the category priority
(ie no threshold set)
* for the email appender, ignore those messages which got past the
category filtering, but are lower than WARN

It is more efficient to filter at the category level than the appender
level, but if you want different amounts of detail written to different

appenders for the same category, then the threshold setting allows you
to do this.

Cheers,

Simon




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[Paul Smith]

And just one more thing to factor in:

log4j.threshold=........

This property defines the base threshold that ALL log events must be
greater than or equal to before going on and evaluating the
category/logger & appender thresholds that have been discussed.

This property is like the primary valve in a water pipe system
regulating the main flow in a very very course manor.

By default this top level threshold is "ALL". But you could set it to,
say, INFO to effectively discard/ignore all DEBUGs in the quickest way
possible.

Hope that helps.

Paul Smith

Post by Kawthar Bt M Sulaiman
Oh ok.... now I understand.
Thank you.
--Kawthar

Post by Kawthar Bt M Sulaiman
Hi,
log4j.rootCategory=debug, MO ----> <first>
Then,
log4j.appender.MO=org.apache.log4j.DailyRollingFileAppender
log4j.appender.MO.Threshold=DEBUG. -----> <second>
...
My question, is the debug <on first> and <debug on second> has the
same
meaning? So, if I just want to log INFO and above, do I change the
Threashold=INFO only or both?

When some code logs a message, it specifies a priority and a category.
If the message priority is less than the category priority, then the
message is totally ignored.
Once the message gets past that first cutoff, some significant work
gets
done (creating a LogEvent object etc), then the message is sent on to
each appender (ie "outputter") associated with the category.
If any of those appenders has a threshold set, then that appender
discards (ignores) the message if its priority is less than the
threshold.
* category X has two appenders: file and email
* for category X, ignore everything lower than INFO
* for the file appender, accept all that pass the category priority
(ie no threshold set)
* for the email appender, ignore those messages which got past the
category filtering, but are lower than WARN
It is more efficient to filter at the category level than the appender
level, but if you want different amounts of detail written to different
appenders for the same category, then the threshold setting allows you
to do this.
Cheers,
Simon
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