[Haskell-cafe] RFC: Extendable and Easy-To-Use Logger (HLogger)

[JP Moresmau]

Jon, thanks for HLogger! For my (small) needs I was looking for a
simple logging solution, and I couldn't get HSLogger to do what I
wanted, whereas your simpleLogger fitted the bill perfectly.
I suppose a good thing would be conditional buffering, as other noted:
in development mode I want to get my log entries flushed to disk
immediately, while in production I don't want to impact the
performance of my running application by waiting for the logs.
I didn't think that the invocations needed to be made easier: I just
used "logNotice logger message", hard to do shorter.

JP

On Tue, Apr 12, 2011 at 11:45 PM, Henk-Jan van Tuyl <hjgtuyl at chello.nl> wrote:
> On Tue, 12 Apr 2011 19:10:09 +0200, Gregory Collins
> <greg at gregorycollins.net> wrote:
>
>> On Tue, Apr 12, 2011 at 6:40 PM, Jon Kristensen
>> <technology at jonkristensen.com> wrote:
>>>
>>> Hello Haskellers!
>>>
>>> As I have now implemented everything that I could think of, I would like
>>> to
>>> ask the Haskell community to give some feedback on HLogger so that I can
>>> continuing improving it. Some questions:
>>>
>>> Do you have any general/architectural thoughts on things I might be doing
>>> wrong?
>>
>> 1) Use "Text" as the string type, not "String"
>>
>> 2) Re: SimpleLogger: writing to and flushing the log file upon
>> receiving each message is absolutely the wrong thing to do in
>> high-performance code. Each write() is a context switch into the
>> kernel, and doing it this way will kill your throughput (in messages
>> per second). What we do in our webserver (which relies on
>> high-throughput access logging) is to buffer messages to the log
>> channel in memory, and perform the actual writes in a separate worker
>> thread no more often than once every N seconds.
>
> If you want to know what the last thing was that your application was doing,
> before it crashed (e.g. at the customers site), you better write every
> message immediately to disk.
>
> Regards,
> Henk-Jan van Tuyl
>
>
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> http://members.chello.nl/hjgtuyl/tourdemonad.html
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-- 
JP Moresmau
http://jpmoresmau.blogspot.com/