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  • Tim 1193 posts 2655 karma points c-trib
    Feb 22, 2010 @ 12:45

    Issues installing on a high traffic / load balanced site


    I installed ImageGen on a large (non-umbraco) site recently, and ran into a few issues that I thought might be of interest! I was using the latest version, with the fix for the caching bug applied.

    The site in question is a large e-commerce site that gets many thousands of visits a day, and lives on a dedicated load balanced setup. I applied ImageGen to a single page to see how well it handled the traffic (the page was the product detail page that contains up to a dozen images), and it started off well, but after a while it degraded the server performance to the point where it was timing out for most site users and I eventually had to remove the code and restart IIS.

    The server is Win2K3, running IIS. The site was a standard .Net 3.5 website, using websforms and the usual .Net stuff.

    The issues we noticed were:

    • Server resources increasing gradually over time while the code was running, the issue was worse the heavier load the server was under
    • Locked files, the server replication software was struggling to copy the imagegen cache XML files from one server to the other, as it was locked by another process, possibly an unreleased lock on the file?

    Hope that's useful! If you need any more info, let me know and I'll get it for you.


  • Douglas Robar 3570 posts 4670 karma points MVP 6x admin c-trib
    Feb 23, 2010 @ 11:49
    Douglas Robar

    I suspect that trying to copy the cache folders between servers in a load-balanced environment is going to be a problem. Partly because file locks do happen and in a very active site some image or cache file may be locked at any time, causing the replication to slow down and the cache between servers to become corrupt over time.

    I would avoid replicating any of the cached folders and let each server manage its own image caches independently.


  • Tim 1193 posts 2655 karma points c-trib
    Feb 24, 2010 @ 00:46

    Hi Doug,

    I'll drop the image folders off the replication list and see what happens, I'll let you know the results.

    Thanks for getting back to me!


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