Question

I need to configure logger to write messages to several appenders with different Log Levels.

For ex. I want RefreshDataService to log detailed info to TransportFileAppender and Warnings and Errors to RollingFileAppender.

Also, I’m using buffering to improve logging performance.
I setup FilteredFileLog appender to forward Warnings to FileLog->RollingFileAppender.

But for RefreshDataService logger, all log messages including debug and Info getting logged to FileLog.

Can you help me to configure the RefreshDataService logger to log only Warn+ messages to FileLog? Thanks.

Below is excerpt from my log4net config.

<appender name="RollingFileAppender" type="log4net.Appender.RollingFileAppender">
  <file value="${TEMP}\logs\client\${ENV}\client.log" />
  <appendToFile value="true" />
  <rollingStyle value="Size" />
  <maxSizeRollBackups value="10" />
  <maximumFileSize value="4096KB" />
  <layout type="log4net.Layout.PatternLayout">
    <conversionPattern value="%date [%thread] %-5level [%property{ENV}] [%property{UID}] %logger - %message%newline" />
  </layout>
</appender>

<appender name="TransportAppender" type="log4net.Appender.RollingFileAppender">
  <file value="${TEMP}\logs\client\${ENV}\client.comm.log" />
  <appendToFile value="true" />
  <rollingStyle value="Size" />
  <maxSizeRollBackups value="10" />
  <maximumFileSize value="4096KB" />
  <layout type="log4net.Layout.PatternLayout">
    <conversionPattern value="%date [%thread] %-5level %logger - %message%newline" />
  </layout>
</appender>


<appender name="DetailedTransportLog" type="log4net.Appender.BufferingForwardingAppender">
  <threshold value="DEBUG" />
  <bufferSize value="200" />
  <appender-ref ref="TransportAppender" />
</appender>

<appender name="FileLog" type="log4net.Appender.BufferingForwardingAppender">
  <bufferSize value="20" />
  <lossy value="false" />
  <appender-ref ref="RollingFileAppender" />
</appender>

<appender name="FilteredFileLog" type="log4net.Appender.ForwardingAppender">
  <threshold value="WARN" />
  <appender-ref ref="FileLog" />
</appender>

<logger name="RefreshDataService" >
  <level value="DEBUG" />
  <appender-ref ref="FilteredFileLog" />
  <appender-ref ref="DetailedTransportLog" />
</logger>

Answer 1

You can use a level range filter on the appender:

<filter type="log4net.Filter.LevelRangeFilter">
    <levelMin value="WARN" />
    <levelMax value="FATAL" />
</filter>
<filter type="log4net.Filter.DenyAllFilter" />

My understanding is that the Threshold property is used tell the appender to flush the buffer when messages of a certain level are logged. This way you can make for instance sure that errors are written immediately to the database.