Re: [web-devel] Caching the System time

extra bonus points: use Kazu's http-date package [1]. Actually, from Kazu's reports most of the benefit from the caching is likely due to avoiding creating the string with haskell's current date libraries. [1] http://hackage.haskell.org/packages/archive/http-date/0.0.0/doc/html/Network... On Sat, Aug 6, 2011 at 11:11 AM, Michael Snoyman wrote:

Without having delved into the issue in any great depth, I had a possible idea on this point. How about storing an IORef containing a time and the text representations you need. Whenever you need to get the time, compare the time in the IORef with the current time, and if they're different, update appropriately. Bonus points: store in an unpacked datatype and use a Builder instead of String. Would this (in theory) work?

On Sat, Aug 6, 2011 at 7:18 PM, Gregory Collins wrote:

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FWIW: we don't cache the system time because it's slow to *get* it -- we cache it because it's slow to turn it into a text string (for HTTP responses, logging, etc). It still may be a stupid thing to do, but it benchmarked faster when I wrote it. G

On Fri, Aug 5, 2011 at 7:47 PM, Bryan O'Sullivan wrote:

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On Fri, Aug 5, 2011 at 7:57 AM, Greg Weber wrote:

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We are finally getting around to implementing a robust logging solution within Yesod. This creates the issue of having to frequently access the system time. I see that Snap has a separate thread to get the system

time

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and cache the result [1].

That is an absurd non-optimisation. It costs just a few dozen nanoseconds to get the time of day under OS X, and Linux should be even cheaper since it doesn't involve a system call. It wouldn't surprise me if the approach above is actually slower. _______________________________________________ web-devel mailing list web-devel@haskell.org http://www.haskell.org/mailman/listinfo/web-devel

-- Gregory Collins

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