Can Log4net have multiple appenders write to the same file

asp.netlog4netweb.config

I'm using a RollingFileAppender to log some info to a file with a conversionPattern (in the web.config) that looks like this for the header of each log section:

<conversionPattern value="%date - %property{userId} - %property{method}%newline--------------------------------%newline%message%newline%newline"/>

I'd like to log details under this header as bullet points. I'm currently trying to use another RollingFileAppender that logs to the same file with a simple conversionPattern of just a dash, like this:

<conversionPattern value="- %message%newline"/>

But these messages aren't making it into the log file. I'm using Log.Info() for the header and Log.Debug() for the bullet points and filtering each appender on their respective log levels. Is what I'm trying to do possible? Or is there a better way to get header and detail information into a log file from log4net?

Best Answer

Yes you can have two log4net appenders that append (write) to the same log file.

You need to place the following line in each of your Appenders:

<lockingModel type="log4net.Appender.FileAppender+MinimalLock" />

This will make log4net use a minimal locking model that allows multiple processes to write to the same file.

Here's an example XML that uses two appenders writing to the same log file:

<log4net debug="false">
<appender name="RollingLogFileAppender1" type="log4net.Appender.RollingFileAppender">
  <!-- this configures a log for the application messages -->
  <file value="TestLog.log" />
  <appendToFile value="true" />
  <!-- next line uses a minimal locking model that allows multiple processes to write to the same file -->
  <lockingModel type="log4net.Appender.FileAppender+MinimalLock" />
  <rollingStyle value="Size" />
  <maxSizeRollBackups value="10" />
  <maximumFileSize value="10MB" />
  <staticLogFileName value="true" />
  <!-- make the most recent log the highest numbered log -->
  <countDirection value="1" />
  <layout type="log4net.Layout.PatternLayout">
    <conversionPattern value="%-5level %date{MM-dd-yyyy HH:mm:ss.ff} [%property{NDC}] %message%newline [Thread: %thread] %c{1} Method:%method(%file{1}, Line:%line) %newline" />
  </layout>
  <!-- The following two filters insure only log requests of 
        version '1' use this Appender -->
</appender>
<appender name="RollingLogFileAppender2" type="log4net.Appender.RollingFileAppender">
  <file value="TestLog.log" />
  <appendToFile value="true" />
  <!-- next line uses a minimal locking model that allows multiple processes to write to the same file -->
  <lockingModel type="log4net.Appender.FileAppender+MinimalLock" />
  <rollingStyle value="Size" />
  <maxSizeRollBackups value="10" />
  <maximumFileSize value="10MB" />
  <staticLogFileName value="true" />
  <!-- make the most recent log the highest numbered log -->
  <countDirection value="1" />
  <layout type="log4net.Layout.PatternLayout">
    <conversionPattern value="%-5level %date{MM-dd-yyyy HH:mm:ss.ff} [%property{NDC}] [Thread: %thread] %c{1} Method:%method(%file{1}, Line:%line) %newline%message" />
  </layout>
</appender>
<root>
  <level value="DEBUG" />
  <appender-ref ref="RollingLogFileAppender1" />
  <appender-ref ref="RollingLogFileAppender2" />
</root>

This can be found in the Apache documentation here: Apache Log4Net Docs Just search on this page for 'same file'.

Hope this helps.

Related Solutions

Log4net – show time (not date) in console

You can use date or utcdate to format a date to your specification:

date

Used to output the date of the logging event in the local time zone. To output the date in universal time use the %utcdate pattern. The date conversion specifier may be followed by a date format specifier enclosed between braces. For example, %date{HH:mm:ss,fff} or %date{dd MMM yyyy HH:mm:ss,fff}. If no date format specifier is given then ISO8601 format is assumed (Iso8601DateFormatter).

The date format specifier admits the same syntax as the time pattern string of the ToString.

For better results it is recommended to use the log4net date formatters. These can be specified using one of the strings "ABSOLUTE", "DATE" and "ISO8601" for specifying AbsoluteTimeDateFormatter, DateTimeDateFormatter and respectively Iso8601DateFormatter. For example, %date{ISO8601} or %date{ABSOLUTE}.

These dedicated date formatters perform significantly better than ToString.

utcdate

Used to output the date of the logging event in universal time. The date conversion specifier may be followed by a date format specifier enclosed between braces. For example, %utcdate{HH:mm:ss,fff} or %utcdate{dd MMM yyyy HH:mm:ss,fff}. If no date format specifier is given then ISO8601 format is assumed (Iso8601DateFormatter).

The date format specifier admits the same syntax as the time pattern string of the ToString.

For better results it is recommended to use the log4net date formatters. These can be specified using one of the strings "ABSOLUTE", "DATE" and "ISO8601" for specifying AbsoluteTimeDateFormatter, DateTimeDateFormatter and respectively Iso8601DateFormatter. For example, %utcdate{ISO8601} or %utcdate{ABSOLUTE}.

These dedicated date formatters perform significantly better than ToString.

Source: log4net PatternLayout documentation.

Configure Log4net to write to multiple files

These answers were helpful, but I wanted to share my answer with both the app.config part and the c# code part, so there is less guessing for the next person.

<log4net>
  <appender name="SomeName" type="log4net.Appender.RollingFileAppender">
    <file value="c:/Console.txt" />
    <appendToFile value="true" />
    <rollingStyle value="Composite" />
    <datePattern value="yyyyMMdd" />
    <maxSizeRollBackups value="10" />
    <maximumFileSize value="1MB" />
  </appender>
  <appender name="Summary" type="log4net.Appender.FileAppender">
    <file value="SummaryFile.log" />
    <appendToFile value="true" />
  </appender>
  <root>
    <level value="ALL" />
    <appender-ref ref="SomeName" />
  </root>
  <logger additivity="false" name="Summary">
    <level value="DEBUG"/>
    <appender-ref ref="Summary" />
  </logger>
</log4net>

Then in code:

ILog Log = LogManager.GetLogger("SomeName");
ILog SummaryLog = LogManager.GetLogger("Summary");
Log.DebugFormat("Processing");
SummaryLog.DebugFormat("Processing2"));

Here c:/Console.txt will contain "Processing" ... and \SummaryFile.log will contain "Processing2"

Best Answer

Related Solutions

Log4net – show time (not date) in console

Configure Log4net to write to multiple files

Related Topic