home
> blog
>> 422
| [previous] / [up] | [overview] | [down] / [next] |
Sun Sep 11 21:07:59 2005 GMT: WRT54G Fimware Hacking
Thu Sep 01 20:26:08 2005 GMT: jabberd2 64-bit brokenness
Wed Aug 24 22:50:57 2005 GMT: Where is all the RAM?
I have been scratching my head for some time now why the company's proxy server performance was quite bad in the past few weeks. Apparently, a lot of swapping was dramatically slowing down the machine, but I just couldn't figure out the reason for all the swapping, because the machine's configuration didn't change for quite a while.
Unfortunately, "ps" or "top" also weren't of much help here - they didn't show any unusual memory hogs, but "free" insisted that there was no free memory and only a few MBs used for buffers and caches.
Today, I finally looked through the /proc filesystem to see if I could find any unusual traces there. And yes, when looking at /proc/slabinfo I noticed that the kernel has allocated around 200000 "sock" object (consuming around 50000 4k pages or 200 MB of RAM). Hmm, maybe this was a left-over of one of those Bitdefender DoS attacks.
Well, a reboot seems to have fixed the problem for now.
Wed Aug 24 19:57:14 2005 GMT: Google Talk
Hmm, they use an open protocol (XMPP) with some proprietary extensions (VoIP signalling, although they claim to be documenting the extensions in the future) to build a closed service (by not allowing XMPP's server-to-server communication). And by installing their client software you "agree to automatically request and receive Updates" from their servers.
Sounds a lot like Microsoft, doesn't it? But, it's not, it's Google Talk.
BTW, there is an interesting article about Google in the IHT: Google taking on Microsoft's role of villain
Sat Aug 13 18:38:40 2005 GMT: Upgrading to Hoary Hedgehog
I have finally upgraded my Linux machine at home from Debian woody to Ubuntu Hoary Hedgehog. As this machine is already quite old, I haven't installed a GNOME/Nautilus desktop, but I have decided to switch to XFCE4 (and keeping fvwm as the window manager, of course).
Tue Aug 09 18:16:19 2005 GMT: One More Reason to Ignore Google
Seems to be a pretty bad week for Google: According to Elinor Mills, Google doesn't like it if you raise privacy issues about their search engine (also see Google gets 'googled,' and annoyed). Now Yahoo has announced that it features the biggest search engine index with nearly 20 billion Web documents.
I am wondering when we can expect an update from number three in the search engine market...
Mon Aug 08 19:17:15 2005 GMT: Concurrent Access To SQLite Database
One of the weak points of SQLite is when multiple threads or processes are trying to access the same database. While SQLite ensures that the database isn't corrupted, the behaviour most likely isn't desirable, because SQLite only uses a very simplistic way of locking. Essentially, it uses polling when waiting for a lock (which might lead to starvation and consequently to SQLite BusyErrors). The SQLite developers are blaming the brokenness of POSIX file locking in multi-threaded programs.
To work around this limitation, I have enclosed database accesses in a mutex in JabRSS (where multiple threads try to access the same database), and I am using POSIX file locking in WebRSS (where multiple processes might try to access the same database). At least I get the desired behaviour with some additional coding.
Sun Aug 07 08:29:41 2005 GMT: Solaris Internals
Tue Aug 02 19:54:03 2005 GMT: Atom 1.0
Sun Jul 31 15:29:04 2005 GMT: Anti-Virus Software Flaws
Wed Jul 13 19:15:04 2005 GMT: Mail System Changes at web.de
Tue Jul 12 19:14:31 2005 GMT: Domain Grabbers
