[kea-dev] Requirements for the Logging and Diagnostics in Kea

Chaigneau, Nicolas nicolas.chaigneau at capgemini.com
Thu Apr 9 07:03:36 UTC 2015


> I have one high level concern which is to make sure that the logging doesn’t end up impacting the performance of the server in general.  Using different log levels should help some there but we may want to do some testing to see if anything more needs to be done (allow to enable / disable some of the logging at run time or at compile time etc).


This is a very valid concern.
I added (within a hook) a log of each received and sent packet as described by Tomek, and noticed a very significant drop in performances.
(by performances here I mean "how many DORA/s can I handle at most")

I tried to disable the automatic flush (see http://kea.isc.org/ticket/3752 about that), which resulted in improved results.

Then I tried to bypass log4cplus completely (using a fstream with flush disabled).
In this case the results are much better.

So I guess the convenience of logc4plus comes at a (big) cost for large volumes of logs.
Maybe there are parameters (besides the automatic flush) that can be tuned to improve performance ?


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