Last week I did a lot of debugging on the Debian server to try and find out what was the issue. And initially it was Dovecots memory usage. After disabling this tool for a couple of days the server was still running fine. However the day after I posted the article on Dovecot the server crashed again. So I had to restart my investigation.

First off I had to had to get a better memory management tool, so I installed Htop on the server (apt-get htop). This shows the current memory usage of each running application. After installing this I enabled all services and applications again and started running stress tests. And though Dovecot was causing some peeks in memory usage it did not keep the high memory usage after the requests where done.

As it turns out for some reason Apache 2.2 was using a lot of memory during peak loads. But even more frustrating it didn’t seem to release any memory any more. Which was causing issues for services that only spawn when they are being accessed like Dovecot and Postfix, which explained why both of these services crashed when the server halted.

After tweaking the maximum amount of servers Apache is allowed to start and the maximum amount of client threads to handle the memory usage dropped dramatically. And I am very happy to report that the server has been running again for more then a week, without any glitches.

Still it doesn’t explain why all of this only happened after updating my server with the latest versions and patches. But I’m glad it’s solved for now.

Why I believe that dovecot is slowely over time eating up memory, well after I disabled it the VPS continued running without any issues. I already knew Apache 2, subversion and MySQL weren’t causing it. So I only had postfix and dovecot left to test.

What is truly amazing is that the website for Dovecot indicates it is low in memory consumption, hence it has no settings to limit the amount of memory allocated for Dovecot. So I still need to figure that part out, or alternatively change to a different IMAP server.

Now off course it is not the fault of Linux , but with my very lacking skill. I recently did an apt-get upgrade command on the VPS. To my suprise it started updating with Lenny packages, whilst I could have sworn I have Etch installed. Mystery on its own, but worse yet the server now keeps hanging and breaking.

I figured it was a memory issue at first cause some weird service was installed that was eating it alive. So I de-installed that and it ran fine for a few days. But allas, after 3 days of running the VPS hangs itself up again. When I say hangs-up I mean that I cannot connect using SSH, the mailserver goes down. MySQL and Apache keep running though, as does postfix. So I’m still guessing it is memory, but I have no idea why my configuration is no longer working after running an apt-get upgrade command. Something is really wrong .

After downloading and burning the image I got from Microsoft I quickly tried to install it on my HP TouchSmart PC. Why did I choose this computer rather then my laptop or mediacenter. Well I was honestly expecting a lot of trouble and my TouchSmart has a recovery disk to quickly revert to Windows Vista .

First look at the Windows 7

The installation of windows was damn easy, I guess when you compare the installation it is very similar to Windows Vista. A graphical interface is loaded that will help you trough the various steps needed  to install Windows 7. So far so good, though it does take quite long to install. But then again who is expecting anything else from a bloated OS, which I still believe Windows is. After the installation most things on my computer are recognized and work fine. Why I say most things, well unfortunately none of the special buttons of my computer are working. So I can’t control the sound, media or the brightness of the screen. Which sucks, but then again I don’t think I can blame Microsoft for that. As HP does not have any support what so ever for Windows 7.

One cool thing I really liked is that after installing a multi touch driver my HP was able to recognize 2 pressure points on the screen at the same time. Which makes for some cool features that work. I really liked it, but keep in mind it is just some eye candy and won’t help you in the every day things you do on the computer .

Some new neat features

Some might have already heard about some of the new features included in Windows 7. Well I will try and summarize a few that I find useful and some of which I have serious doubts that they are any added value what so ever.

More decent window grouping
Anyone who has used Windows XP or Vista knows about the feature that windows starts grouping similar windows when there are a lot of them open. Well in windows 7 this feature got extended. Now it groups the windows no matter how many are open. This on its own is not that bad. Because like in Windows Vista you get a small preview of the window when you hover over it. A new feature in this is that when you stay over a window for a longer period of time the window will be displayed on the screen and all other windows ‘disappear’ to the background.

Though this is a pretty stable and nice feature I strongly dislike Windows for doing this same thing for every single tab in Internet Explorer. Which is pretty annoying to people like me who have several tabs open, as well as several instances of Internet Explorer. This causes it to become a bit crowded down in that small preview window.

Better quicklaunch features
One of the older features in windows is the quicklaunch bar in the taskbar. This allows you to quickly start up any program you pinned to it. Well Windows 7 is no stranger to this. It features this prominently and slightly changed. The icons are a lot bigger then before, and like before you can pin any application to the taskbar. One new thing is that if you click on an icon and drag up a quicklaunch window appears with the most used actions, or in case of the explorer the most opened folders.

Speed compared to Vista

A lot of people are comparing Windows 7 with Vista, which I guess is not that strange since they look very similar. One huge improvement is that Windows 7 appears to be a bit quicker and slimmer then Vista. I have not done extensive tests speed wise, but it looks like it boots up a bit quicker and closes quicker. As well as loading of applications this also appears to be slightly faster.

The eye-candy included in Windows 7 is a bit sluggish tough. It’s just that bit lagging behind on commands giving. Like dragging of applications seems to bit just a bit slow. It might have todo with my HP TouchSmart, but Vista runs on it beautifully so I would expect Windows 7 to do the same.

Some related video’s

Like all of you I like vid’s, so I added some nice reviews and feature video’s below. Enjoy them and until next time…

Before this update of PowerDVD the weird behaviour was the disapearing of PowerDVD when playing discs. No message no error nothing, just gone! After the update the DVD player informed me that HDCP was not available and it could not play protected Blu-Ray discs.

This sounded weirdt to me since I have played them in the past, and I know the onboard graphics chip (the Ati Radeon X1250) supports it.

As it turns out, after a lot of digging, I had recently installed an updated version of the Catalyst Control Center. Which should not be anything strange, its recommended practice by a lot of software developers. However the graphics chipset on the motherboard appears to have some custom stuff, since after installing the latest version from the Ati site HDCP was no longer supported.

When I reinstalled the version of the Catalyst Control Center that came with the PC all my troubles went away. No more warnings / crashes or unable to play disc reports.

You are not alone. I wasn’t even sure if such a thing exists either. Well the first part of the quest was very easy, find a computer that does not have a seperate casing for the actual computer. So an all in one system. Well these things actually exists, I mean look at the iMac. So I know they are out there, I just don’t want an iMac because non of the software I use is available for it. And I’m not a big fan of the Apple company, but that’s a completely different story all together.

It was only a couple of days later that by accident I came accross a small poor quality video of the HP TouchSmart series. Which appearantly has been out ever since early 2007. These computers have everything build into the monitor, not just that but they are touch enabled. And I say touch enabled because they don’t have a touch screen in the traditional sense. The HP TouchSmart series has a shit load of LED’s build into the screen that detect where you press on the screen (and no you don’t even have to touch the screen for the LED’s to detect the touch).

Initially I was considering either a late model of the IQ500 series, which was brought out in 2008 or the IQ800 series which was brought out in 2009. The trouble with my little quest was that the 800 series is currently very hard to get. When I called several shops they could not get any computers in that series at all! So I ended up going for the IQ532, which was the best out of the IQ500 series currently available. And I can honestly say I like it, no more wires. And best of all you can choose to not use the mouse or keyboard. The touch part works pretty damn good, even with the onscreen keyboard that HP made for us as you can see in the screenshot below.

So I really like it, I mean the HP Touch application that is provided is pretty useless to me. But the idea of not needing anything and only having a single cable for your entire computer. Having bluetooth, WiFi and even a TV Tuner integrated is perfect for me. So just for you I have included some YouTube movies on the HP TouchSmart Series.

I have my own root certificate for all of my websites, so that I can sign my own certificates and use them all over the place. I only have to ask my clients to accept the root certificate and all is fine. This seems to work fine except when I tried to load them into Apache. Here’s what my problem is and was. I have multiple domains hosted on the same virtual server. Which basically means a lot of websites running under one IP-address.

In this setup I have several domains I want to add a SSL variant of. For example webmail.domain.com as well as admin.domain.com. And this is where it became problematic.

I configured this without any problems in apache. Setup a virtual host listening to port 443 and setup the listener instruction in apache. But for some reason all of my secure domains ended up using the same certificate. Which off course causes a lot of security warnings for the browsers . And a lot of people are having the same issue, just read the thread on howtoforge.com.

As it turns out Apache is only able to host one secure virtual host per IP-address and port combination. Which is kinda obvious since Apache cannot read the domain name until it has decrypted the SSL information, something which it cannot do until the SSL handshake with the client has been done. Hence that only one set of certificates is allowed per IP and port.

Long story short I ended up setting the websites up with different ports since I don’t have multiple IP-addresses to host the websites on.

Unfortunattely for me and my clients the problem seems to be with the provider I have to rent my servers. After some digging I found out even their own servers where unreachable. (Could not even setup a SSH connection to my servers).

It seems to be fixed at the moment, so keep praying that it stays that way .

So why is this a nice feature to have, well because I am a very lazy progammer and this feature allows me to magically generate getters and setters. To do this I have the following setting for each class:

1. The constructor method __construct initializes an array containing the names of all variables that we want to store. We also create a second array to save the values in for the variables.
2. We implement the __call function to catch all functions being called on the object, which is currently still undocumented by PHP.net

So a basic class would look something similar to this:

class MyObject {
   private $my_vars = array();
   private $allowed_vars;

   function __construct() {
      $this->allowed_vars = array('var1', 'var2', 'var3');
   }

   function  __calls($function_name, $arguments) {
      $_variablename = substr($function_name, 3);
      if (array_search($_variablename, $this->allowed_vars) !== FALSE) {
         if (stripos($function_name, 'get') == 0 && stripos($function_name, 'get') !== FALSE) {
            return $this->my_vars[$_variablename];
         } else if (stripos($function_name, 'set') == 0 && stripos($function_name, 'set') !== FALSE) {
            $this->my_vars[$_variablename] = $arguments[0];
         }
      }
      else throw new Exception('Unkown function called on '. __CLASS__);
  }
}

Which does exactly that which I described above. Mind you it’s just a very basic example but it shows the power of a catch all function.

I will attempt to start posting somewhat more regularly from now on again, as I’ve sorta managed to get some stuff out of the way. One of them is my work on a complete overhaul of a part of the platform that the Zylom site is running on. Well enough of that!

Ok so what have I been up to that caused little posts. One of my new projects was a complete change of the corporate website I have been maintaining. It’s not live yet, but great things are comming for this website. Which also gets me into the next phase of my career, as I am now looking into starting my own company, and it is really a scary thought 8-O.

I will soon start writing some more posts on developing website platforms in both PHP and Java, as I’ve been learning a lot recently for each one of these two languages.