Questions tagged [log4net]

The Apache log4net library is a tool to help the programmer output log statements to a variety of output targets. log4net is a port of the excellent Apache log4j™ framework to the Microsoft® .NET runtime. We have kept the framework similar in spirit to the original log4j while taking advantage of new features in the .NET runtime.

Apache log4net is a tool to help the programmer output log statements to a variety of output targets. In case of problems with an application, it is helpful to enable logging so that the problem can be located. With log4net it is possible to enable logging at runtime without modifying the application binary. The log4net package is designed so that log statements can remain in shipped code without incurring a high performance cost. It follows that the speed of logging (or rather not logging) is crucial.

At the same time, log output can be so voluminous that it quickly becomes overwhelming. One of the distinctive features of log4net is the notion of hierarchical loggers. Using these loggers it is possible to selectively control which log statements are output at arbitrary granularity.

log4net is designed with two distinct goals in mind: speed and flexibility.

Features:

  • Support for multiple frameworks
  • Output to multiple logging targets
  • Hierarchical logging architecture
  • XML Configuration
  • Dynamic Configuration
  • Logging Context
  • Proven architecture
  • Modular and extensible design
  • High performance with flexibility

Support for multiple frameworks:

log4net runs on all ECMA CLI 1.0 compatible runtimes. log4net has specific builds for the following frameworks:

  • Microsoft® .NET Framework 1.0
  • Microsoft .NET Framework 1.1
  • Microsoft .NET Framework 2.0
  • Microsoft .NET Framework 3.5
  • Microsoft .NET Framework 4.0
  • Microsoft .NET Framework 3.5 Client Profile
  • Microsoft .NET Framework 4.0 Client Profile
  • Microsoft .NET Compact Framework 1.0*
  • Microsoft .NET Compact Framework 2.0
  • Mono 1.0
  • Mono 2.0
  • Microsoft Shared Source CLI 1.0*
  • CLI 1.0 Compatible
  • Microsoft .NET Core 1.0 providing .NET Standard 1.3

The "Client Profile" builds are stripped down versions of the "normal" builds that don't contain any ASP.NET releated code - which for example means the %aspnet-* patterns and the AspNetTraceAppender are not available.

* Not supported by the binary release but can be built from the source release.

Official Website: http://logging.apache.org/log4net/

Useful Links:

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How to log stack trace using log4net (C#)

How to log stack trace with log4net? I am using .Net version. They way I have is Log.Error(ex). Thanks
CoolArchTek
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Should I declare log4net logger once per class or in base class?

It seems cleaner to declare a logger and call LogManager.GetLogger in a base class so that everyone who is inheriting can use it. However, on log4net site and other blogs like in this blog post it states that it is better to declare one logger per…
dev.e.loper
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Why is the date appended twice on filenames when using Log4Net?

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,…
Hertanto Lie
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Thread Safety of log4net

There seems to be some discussion on whether log4net is thread-safe, the consensus is that the framework is thread-safe, but appenders are not and need to be used correctly to achieve thread-safety. can someone shine some light on this and possibly…
Alex
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Log4net C#4.0 [(null)] in output

When I use log4net for logging in .NET4.0 I use the following code LogManager declaration: private static readonly ILog log = LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType); And when used in code: log.Info("My…
UncleBlue
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ASP.Net MVC Exception Logging combined with Error Handling

I am looking for a simple solution to do Exception Logging combined with Error Handling in my ASP.Net MVC 1.0 application. I've read lots of articles, including Questions posted here on StackOverflow, which all provide varying solutions for…
Saajid Ismail
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How to write log4net config into appsettings.json?

I have implemented log4net into .NET core 2.0, to log into a text file. As log4net have a config file, which is having XML configuration in it. So, I have created a separate file log4net.config to set its configuration and it is working fine. But I…
DevProf
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What is the root logger in log4net

I don't quite understand what the main functionality for root logger as shown in following section is. What is the difference from other loggers?
Ricky
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Can Log4net have multiple appenders write to the same file?

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:
adam0101
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How I can set log4net to log my files into different folders each day?

I want to save all logs during each day in folder named YYYYMMdd - log4net should handle creating new folder depending on system datetime - how I can setup this? I want to save all logs during the day to n files of 1MB - I don't want to rewrite old…
halex
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log4net configuration from web.config is not loaded - why?

Below is my config and the output from tracing, it just doesn't configure the logger and when I use it nothing is written to the log (probably because all log levels are not enabled). What could be the problem?
michaelr524
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How to Inject Log4Net ILog implementations using Unity 2.0

Ultimately this has to do with setting up log4Net but generically the problem is not logging specific. Generically what I am trying to figure out is how to do, in Microsoft Unity 2.0, something equivalent to what one gets with the…
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How to log different log level to different log appender in log4net

I have a WinForm that it display log information but I want it to display to only INFO level but I want the log in the log file to contain DEBUG level as well. Below is my configuration: