C# – Change log4net logging level programmatically

clog4netlogging

This is similar to 650694 but no answer was accepted there, I can't get any of those suggestions to work at all, and I suspect I may be in a slightly different situation.

I'm calling log4net.Config.XmlConfigurator.Configure(). But after that point in the program, I want to change the logging threshold to a value only known at runtime.

From the other question, I tried:

((log4net.Repository.Hierarchy.Logger)mylogger.Logger).Level = log4net.Core.Level.Error;

and:

var appender = new log4net.Appender.ColoredConsoleAppender();
appender.Layout = new log4net.Layout.PatternLayout(@"%date %-5level %message%newline");
appender.Threshold = log4net.Core.Level.Error;
appender.ActivateOptions();
log4net.Config.BasicConfigurator.Configure(appender);

but neither one seems to have any effect: I'm still seeing DEBUG and INFO logging statements on the console.

My hunch is that I'm adding a new appender, which has no effect on the appender declared in the XML config (which tells it to print DEBUG level messages), but I don't have any evidence for this yet.

I've been digging through the log4net API for a while now, and I'm just not seeing it. Is there something simple I'm missing?

Best Answer

None of these solutions present here worked for me. It wasn't changing at runtime

Here is what worked for me:

((log4net.Repository.Hierarchy.Hierarchy)LogManager.GetRepository()).Root.Level = Level.Debug;
((log4net.Repository.Hierarchy.Hierarchy)LogManager.GetRepository()).RaiseConfigurationChanged(EventArgs.Empty);

You have to call RaiseConfigurationChanged after making changes to its config.

Related Solutions

C# – Changing the log level programmatically in log4net

You can programmatically change the Logging level of a log4net logger, but it's not obvious how to do so. I have some code that does this. Given this Logger:

private readonly log4net.ILog mylogger;

You have to do the following fancy footwork to set it to Debug:

((log4net.Repository.Hierarchy.Logger)mylogger.Logger).Level = log4net.Core.Level.Debug;

Log4net vs. Nlog

I was recently tasked to "prototype up some loggin'" for an upcoming project. I didn't have any logging framework experience. I researched, ran through tutorials, made toy apps, etc. on Log4Net, NLog, and Enterprise Library for a few days. Came back 3-4 weeks later and put them together into a cohesive demo. Hopefully some of this is useful to you.

My recommendation for our project is this:

Use a logging facade (e.g. Common.Logging, SimpleLoggingFacade) to avoid direct dependencies.
If we end up using Enterprise Library for other facilities, then use it for Logging, too.
If we end up using something with a dependency on Log4Net, use Log4Net.
If none of the above, use NLog. Which I'd prefer.

That's based on these findings (opinions!):

All 3 frameworks are capable and can do some sophisticated things. We want a quality solution, but frankly don't need ultra high performance or 60 types of event sinks.
All 3 have very similar basic concepts.
Each has its own cool tricks, like really advanced routing, or dynamic log filenames, file truncating, etc.
All 3 are pretty well documented in their own way.
For a complete newb like me, they were all a little awkward initially. No drastic differences here for the basics. I got over it.
When revisiting things a few weeks later, NLog was clearly the easiest to resume. I needed very little brush up on it. With Log4Net, I had to revisit a few online examples to get going. With EntLib, I gave up and did the tutorials all over again from scratch - I was totally lost.
I couldn't figure out how to get EntLib to do some things like log to the database. It might be easy, but it was beyond my time limit.
Log4Net and NLog have a small in-code footprint. EntLib is spammy, but I'd use a facade over it anyway.
I accidentally mis-configured EntLib and it told me at run time. Log4Net didn't. I didn't have an accidental mis-config with NLog.
EntLib comes with a nice looking app.config editor, which you 100% need. NLog has a config file schema so you get "intellisense". Log4Net comes with nada.

So obviously I like NLog so far. Not enough to use it in spite of having another solution available, though.

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