Why is the date appended twice on filenames when using Log4Net?

Question

I was trying to add the date to my log file name and I was able to make it work by following the few suggestions I've found in stackoverflow. Everything works fine but for some reason, the first file always has the date appended twice.

For example, instead of log.2009-02-23.log, I get log.2009-02-23.log.2009-02-23.log.

I found it so weird and fyi, this is a very simple code. It's not like I have it running in a multi-threaded environment.

My log4net config:

<log4net>
<appender name="MyLog" type="log4net.Appender.RollingFileAppender">
    <file value="../../Logs/Mylog"/>
    <staticLogFileName value="false" />
    <appendToFile value="true"/>
    <rollingStyle value="Date"/>
    <datePattern value=".yyyy-MM-dd.lo\g" />
    <lockingModel type="log4net.Appender.FileAppender+MinimalLock" />
    <layout type="log4net.Layout.PatternLayout">
      <conversionPattern value="%d{DATE} [%t] %-5p %c - %m%n"/>
    </layout>
</appender>
<root>
    <level value="INFO"/>
    <appender-ref ref="MyLog"/>
</root>
</log4net>

Any ideas why?

Edit: I want to add the information about the environment I'm testing this in.
- asp.net
- .net framework 2.0
- windows server 2003 64-bit service pack 2
- log4net 1.2.10

Answer 1

This happens if there is a problem accessing the log file when you initialize the log system. It can happen if you initialize the log system twice, if you run your program while another copy is running and writing to the log file, or if you are editing the log file in a text editor. Basically anything that causes a write lock on the log file when log4net init runs.

Check your code for duplicate calls to log4net init - perhaps you are initializing in a constructor instead of in a singleton's static constructor or global init, for example.

This can also happen if you are running in a 'web garden' configuration and don't include the PID in the filename, because each different web server process tries to write to the same file. If using web gardens and writing to files, add the pid to the filename pattern so each server process gets its own file.