log library: Which one, proved and experienced would you advise?

[nguillot]

Hello, the question is in the subject.

Some log libraries exist in C++, Log4cpp, log4cxx, Boost.Log...
But are those libraries widely used in industrial software production?

Thanks for your answers

[JohnW@Wessex]

Be aware that if your application has time critical sections or high priority threads, that the locking used by most logging libraries can have a detrimental effect on timing, by causing priority inversions when a low priority thread logs.

Ironically, it was after looking at the log files that we discovered that it was the logging that was causing the problem in the first place.

[JohnW@Wessex]

Does anyone else have any views on logging libraries?

[ninja9578]

I wrote my own logger using regular FILE *s, pthread mutexes. They aren't terribly complicated and writing your own gives you absolute control over what gets logged.

[nguillot]

Indeed implementing its own log lib allows doing exactly what you want.
But what I want is to earn time, and what I don't need is absolute control...

Moreover, I think a proved (because mature and used) library provides
- better efficiency about log system overhead
- better filter options
- easier configuration
- ...
And I also think a log system is not a purpose for a developer (or rarely, maybe for a log library developer), but a tool.

That's why I ask about a library.

[JohnW@Wessex]

Boost.Log may be a good bet if you want a library that may, in time, be integrated in to the standard C++ libraries.

[JohnW@Wessex]

I wrote my own logger using regular FILE *s, pthread mutexes. They aren't terribly complicated and writing your own gives you absolute control over what gets logged.

We wrote our own because of the timing difficulties I mentioned.We devised a low impact way of sending log data to a low priority thread that actually did the logging. Logging sections are enabled via a configuration file, including log levels.