How well did Super Cache handle the digg?

I must admit making the front page of wasn’t the nail biting experience I expected.

$ grep "GET /2007/11/05/wordpress-super-cache-01/" access.log.1|grep digg -c

My Super Cache announcement only drew 4686 visitors which is an ultra-light Digg. The Digg page for the post received 808 diggs as of a few minutes ago which is great. Thank you for voting! Judging by the sheer number of comments on that post, there’s a lot of interest out there in the plugin.
What about traffic graphs? The spike at the end of the first graph is my nightly Backuppc service kicking in. The second is from Google Analytics. My server could certainly handle a lot more traffic! traffic

A quick look at my uptime shows the server hardly broke a sweat dealing with the extra traffic except where some idiot spammer bots tried to download my archives a few times. Unfortunately the first time that happened the archives weren’t cached and the load climbed.

For maximum performance, download Xcache and install it. The Xcache WordPress plugin uses Xcache to cache data structures and makes WordPress much faster, even if you don’t use any other caching tool.

Author: Donncha

Donncha Ɠ Caoimh is a software developer at Automattic and WordPress plugin developer. He posts photos at In Photos and can also be found on Google+ and Twitter.

33 thoughts on “How well did Super Cache handle the digg?”

  1. Hmmm, I was expecting a bit more than that to be honest. In fairness, due to the nature of the story (non-apple) it probably didn’t get as much as a “normal” digg.

    There was a lot of talk in the comments about the speed you served the page, I am assuming that you had/have xcache running?

  2. Yes, Xcache is installed and I’m really impressed with it and the WordPress plugin. The one thing that worried me about the Digg was the effect people leaving comments would have on the site. The more conversation on that post the more often the static page would have to be regenerated. That’s why it’s important that PHP runs as fast as possible, even with static files being served.

  3. I was thinking of checking super cache out. About the only thing stopping me is that my own site is cached twice already. First with eAccellerator and then by Squid.

    Does super cache play nice with eAcellerator?

  4. Robert Synnott – Oops, that’s a bug in the Subscribe to comment plugin. If I moderate a number of comments at the same time from different posts it gets confused about who to send notifications to. I just upgraded the plugin so hopefully that will fix that!

    Robert – it plays extremely well with Eaccelerator. I used that opcode cache before moving to Xcache and it was fine. Squid will cache the html files extremely well too šŸ™‚

  5. i`m using it with apc cache on my little server and it works really nice – just recognized, a new post doesn`t clear the cache since super-cache v0.3..

  6. I`ll try to post something again (of course there will be news about usa or turkey today.. šŸ™‚ ) and i`ve changed from apc to xcache because of the positive opinions here.. let`s see. šŸ™‚

  7. hm i tried it with a new post but it still just appears on the startpage if i clear the cache after posting, with 0.2 it immediatelly appeared, i`m confused.. šŸ™‚

  8. its more confusion because comments are refreshing immediatelly.. maybe its because i`m using the nightly trunk of wordpress, so.. just wait and see.

    have a nice day, all together šŸ™‚

  9. Uhmmmm… I installed Xcache and I see no difference. my hosting interface is cPanel.

    here’s the info:

    cPanel Version 11.15.0-RELEASE
    cPanel Build 17665
    Theme x3
    Apache version 2.0.61
    PHP version 5.2.4
    MySQL version 5.0.27-standard
    Architecture i686
    Operating system Linux
    Shared Ip Address
    Path to sendmail /usr/sbin/sendmail
    Path to PERL /usr/bin/perl
    Kernel version 2.6.9-023stab044.
    cPanel Pro 1.0 (RC1)

    Am I using the right cache program here?

  10. Absolutely wonderful! Also, thanks for the link to the XCache mod for WordPress. I’ve been using XCache for a while now and was actually considering creating a plugin to store data in the Var cache. That link just saved me a couple hours of work figuring out how to do it.

  11. Hi… I installed supercache .1 and I see there is .3.1, but there is no explaination of what changed (no version logs)

    I came here and I found that you recommend Xcache too. Is Xcache compatible with supercache and if so how are they different?

  12. Hi Jason,

    i ve got some blogs running and with the xcache 2.0.0-dev some blogs with the xcache plugin give me a blank page at load.. whats your xcache settings in php.ini and do you have some special hints?



  13. what kind of hosting (dedicated/shared/company/etc) do you have? I’m curious b/c I hit the digg homepage yesterday as well … for like ten minutes before my site shut down and then I quickly moved off of it (which sucks) – this is the second such time that my webhost hasn’t been able to handle an influx of traffic and led to nonresponsiveness (or worse) – I’m getting tired of the fact that nearly anytime I get a good link (digg, collegehumor,, whatever) my site crashes and I lose that big traffic opportunity – the first time I didn’t have wp-cache enabled – yesterday, I did, and from the digg comments it looks like that even when the diggs were only up to 70, the site was gone (

    I will be looking at super-cache and other ways to try to improve loading, but I’m thinking the real significant change I’ll need to make is in host (currently w/ DreamHost)



  14. Donncha,

    I installed the updated version on one of my blogs. It made me recreate the advanced-cache.php file that the first version’s readme file had me eliminate. It seems to be working.
    I’m putting the duration much higher than the default. I’m setting the supercache to 24 hours and the other cache to 3. Hopefully that will reduce Bluehost’s CPU use complaint. Thank you for the plug in.

  15. @Sara,

    Unless you’re a tester you shouldn’t be using any version of XCache other than the stable release (currently 1.2.1).

    Since this is kind of off topic for this post, if you want to know more about my XCache configs (I run XCache on close to 20 web servers) then email me using the contact form on the “About” page on my web site.

  16. Thanks for this plugin! I went from 76 requests a second (tested with ab2) to 567 requests a second running just your plugin. (Installing APC/Xcode has been on my agenda, but I never got around to it.)

    Your site seems to have held up well, but I wonder about your comment regarding the overhead of regenerating the cache every time someone leaves a comment… I wonder if it would make more sense to add a little logic that keeps a cached page from being updated more than, say, once every 60 seconds? (Maybe the interval could be user-configurable.) The risk of someone loading a cached page and missing the latest couple comments is a small price to pay for the site staying up in a storm.

    But that’s just for extreme situations. Things are about 800% faster using your plugin. Thanks again!

  17. Good Morning Jason, Donncha,

    thanks for all your reply and work – xcache and super cache are working just fine now – i think it really was related on the dev 2.0.0 of xcache – 1.2.2-dev just works great but i think the xcache optimizer will only be a good choice in 2.0.0 because in all 1.2.x trunks it does nothing in my mind, does it?

    Jason, i`m going to contact you, thanks for it!

    Have a nice day! šŸ™‚

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