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Re: Using binary search to get the last 15 minutes of httpd access log

by sundialsvc4 (Abbot)
on Aug 04, 2012 at 17:54 UTC ( #985451=note: print w/replies, xml ) Need Help??


in reply to Using binary search to get the last 15 minutes of httpd access log

I think that it is categorically a good idea to keep your individual files to hundreds of megabytes or maybe couple of gigabytes sizes.   Rotate them frequently on size and compress them; the logrotate daemon is great for all that.   A single, contiguous, gigantic-file is an awkward thing for both you and the operating system to handle.

When you process the file sequentially (and especially if you can “hint” to the OS that you intend to read the file from stem to stern), the operating system is automagically going to do a lot of buffering for you.   It will take deep draughts of the file data each time it does a disk-read.   In short, the operation will be quite a bit faster than you think.

Now that, of course, assumes that the drive is local to the machine that is doing the reading.   If data is flowing across any sort of network wire, then the situation is utterly and completely different ... such that you basically need to find a way to do the work somehow on the locally-attached machine.

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[Corion]: ambrus: Hmmm. It makes sense that AnyEvent would implement the push_write itself, but I think I don't have a good idea of where the boundary between AnyEvent and the underlying event system lies... Implementing the timer should give me a better idea
[ambrus]: Corion: push_write is in the higher level abstraction of AnyEvent::Handle, not in the watcher
[Corion]: ambrus: Hmm - rereading Prima::File, that merrily coincides with what Prima does - it tells you "you can read", and you're supposed to read from the fh yourself. I thought it called you with the data already read, which would've been harder to integrate
[ambrus]: you just need an io watcher, created by &AnyEvent::Impl:: Whatever::io(...)
[Corion]: So after talking it through with you even while I'm still not entirely clear on where AE ends and my implementation begins, I think I understand that I only need to implement some smaller parts for each functionality I want to support.
[Corion]: Yeah... and you might even be able to mix and match additional functionality if you have additional async suppliers, like from a separate thread
[ambrus]: You hvae to be careful with the timer, because apparently Prima::Timer insists on being periodic, wheras AnyEvent::Impl:: Whatever::timer should give a one-shot timer watcher

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