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

[Henk-Jan van Tuyl]

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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