Awasu » Heisenbug
Friday 6th July 2007 4:05 AM [General]

I just nailed a bug in Awasu that has been around for quite a long time but has been incredibly difficult to track down, resisting several attempts on my part to find it.

Until now, and I'm so happy it's gone :jig: 'cos it was really pissing me off :mad:

The problem was that Awasu was getting stuck during shutdown and either not exiting properly or crashing. Most of you probably won't have even noticed it unless you were watching things in Task Manager but I have special diagnostics turned on that alert me when Bad Things like this happen and it was happening a lot :-( The bug was groan-inducingly, head-bangingly obvious, once I found it, but finding it proved to be incredibly difficult.

One of the fun things about working in I.T. is that computer programmers are well known for their love of wordplay and a lot of the jargon has a definite bent feel to it. One of my favorites is heisenbug a reference to Heisenberg's Uncertainty Principle. An important concept in physics, the usual lay description of it is that the very act of observing something affects what is being observed, making experiments and the like difficult since simply looking at what's happening changes the result!

In computers, a heisenbug is a bug that goes away when you start looking for it, the process of trying to figure out what's happening changes the environment enough to make it not happen. Obviously, these kind of bugs are insanely difficult to deal with.

It turned out that this particular bug happened if new content arrived at just the right time when Awasu was shutting down. Since I suspected the problem had something to do with channels updating, I'd be sitting there constantly updating all my channels trying to get it to happen but the more often I did this, the less likely it would be that new content would arrive. In other words, the longer I spent looking for the problem, the less likely it was to happen.

Sigh... :wall:

4 Responses to this post

Congratulations! Now that hte heisenbug has been fixed, I was just wondering when we can expect to see it a release, alpha, beta or otherwise? As you can tell, I've been patiently, impatiently waiting for this one.


I'm just finishing up the re-architecting of read/unread items and testing of one more optimization that should make Awasu have less impact on the rest of the computer when it's working hard. Chuck in a few other bug fixes, I'd say 2.3.1.alpha1 will be out in 10-14 days.

Thanks for the update. I'm looking forward to playing with it.

I'm looking forward to releasing it. Nothing worse than having a lot of new features and fixes that people have been waiting for, running only on my computer :roll:

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