Can you tell that dusk is my favourite time of day for photography? 
Clifton Suspension Bridge
February 16th, 2010Solution to “No such file or directory: Couldn’t initialize cross-process lock in child” in Apache 2.2.13 on FreeBSD 8.0
February 12th, 2010This issue in the Apache error log was causing the web server to “partially crash” during a graceful restart with the following errors:
[Tue Feb 09 18:24:52 2010] [emerg] (2)No such file or directory: Couldn't initialize cross-process lock in child (/etc/opt/HybridCluster/apache2/logs/accept.lock.82760) (5)
[Tue Feb 09 18:24:52 2010] [notice] Apache/2.2.13 (FreeBSD) PHP/5.2.11 with Suhosin-Patch mod_ssl/2.2.13 OpenSSL/0.9.8k configured -- resuming normal operations
[Tue Feb 09 18:24:52 2010] [alert] Child 85206 returned a Fatal error... Apache is exiting!
Previously reported here, this issue occurs when hammering Apache simultaneously with requests and graceful restarts. Sometimes it would take several hours for the problem to manifest. The consequence is that Apache gets stuck with only two worker processes, meaning that requests succeed but very slowly — as they get queued — when under any load. Insidious! The solution was to change the type of locking Apache was using in httpd.conf:
AcceptMutex fcntl
This is a problem on FreeBSD 8.0 with Apache 2.2.13 using the prefork MPM, with the default UFS2 filesystem for the locks directory.
I hope someone finds this useful!
Virgin Media respond to Twitter!
December 14th, 2009Update: Virgin were crap, nothing ever got fixed, and they sent a 17 year old “engineer” who didn’t know what a Traceroute was. We’re now happily on an ADSL line, soon-to-be with the nice folk at Bethere.co.uk.
This is my latest post on the Virgin Media support newsgroup (virginmedia.support.broadband.cable on news.virginmedia.com):
I just had a very interesting 20 minute phone conversation with Jason Golik (see http://www.linkedin.com/in/bungieboy) a senior Network Operation Centre shift manager at Virgin Media.
He got in touch with me via Twitter after I started tweeting loudly about how poor the quality of service and support at Virgin was.
Now, the bad news is that Virgin aren’t going to fix this particular problem with upstream capacity in Bristol until January 4th at the earliest since they have a freeze on engineering work over the holidays!
The really bad news is that the customer support staff on the phones and on the newsgroup would never have told us this! They’d just keep us hanging on with more of this “we have no update on this yet” or “it will be fixed on December 9th” or “Kam will not contact you today” bullshit.
The good news is that there’s someone with an ounce of clue and (potentially) enough power to get problems sorted, and that he’s happy to phone you personally if you make enough noise about the problem on Twitter (because it’s bad PR obviously). So, power to the consumer through social networking!
Unfortunately that’s not enough to keep me with Virgin Media — unless, and here’s a challenge for you Jason — you can get the problem sorted before the morning of December 17th — this Thursday — because that’s the last date I can cancel the installation of the BT line before I’m tied into an 18 month contract with BT.
And I don’t mean just get the problem sorted for ME — I mean for everyone experiencing serious packet loss in Bristol.
Anyone who wants to have a similar conversation can contact Jason by tweeting with the text “@bungieboy” in your tweet. Adding the hashtag “#virginmedia” may also help get you heard.
In a way it’s completely ridiculous that it took 3 weeks to get nothing from VM via the “regular” support channels (even though the NNTP server is hardly your average user’s cup of tea), but that simply by broadcasting my discontent on Twitter, I got an instant and satisfactory response.
Well, satisfactory in that it was at least honest about the timescales. Jason wasn’t able to confirm whether I’d get compensation or free contract termination as a result of these problems, but he did suggest that having documented communications with support over the last 2-3 weeks would help my case.
Let me know your experiences, this will be an interesting one.
Cheers,
Luke
CRU hack — taking a step back
December 12th, 2009The CRU hack really made me stop and think about my views on global warming, in particular this article at The Register was interesting to me as a programmer because it points to some analysis of the data which is a pretty damning read. Specifically this analysis of the “Harry Readme file” is very fierce in its criticism — and rightly so, it looks like the source code and comments that we got to see were pretty awful.
But I think it helps to take a step back: We have no idea who the hackers were, but consider the possible range of their political motives. If they were lefties, it’s fair to say they wouldn’t have done it. It’s possible that they had no political motive but just wanted to get “the truth” out there. But it seems much more likely to me — especially given the timing just before Copenhagen and the impact they must have known it would have, that the hackers were climate-change deniers intent on causing as much disruption to the public impression of scientific consensus as possible. And it worked — it made me question what I had hitherto considered to be scientific fact.
Indeed their political motives seem to be reflected in the code and text the hackers chose to expose. Since they hacked the CRU’s fileserver, they would have had access to enormous amounts of data and code. And they managed to find some pretty nasty stuff in there. The problem is, any large project has a fair amount of bad code and confusing documentation, often not currently used but stored away in case bits of it might be useful later. So we almost certainly didn’t get a balanced view of the work that the CRU do, we just saw the darkest corners of their fileservers. If it is the current status quo, then the CRU has a big apology to make, and some serious data management and software engineering to learn, fast. But one must be very careful in making assumptions based on incomplete information.
So here’s an idea: why don’t the CRU balance out the bad code by releasing all their code, warts and all, under an open-source license? Then we’d know whether the source code that we got to see was indicative of a real problem — also we’d get to see whether the bad code released is still being used for modern climate modeling, or whether it’s been superseded by something of higher quality.
It helps to balance the arguments from the likes of The Register with this editorial from Nature. Coming from an academic background at Oxford University, it’s fair to say that in my experience academics are truth-seekers, and peer-reviewed journals are still the best way we’ve got to be rigorous about our science.
Will O2 replace my defective Pre? [No, but Palm did.]
November 9th, 2009Final Update: Palm did replace my Pre by sending a brand new one via UPS within a week of me sending in the pictures – pretty impressive. Their tech support was pretty good too, they are based in Argentina but they were good at their English and friendly. The new phone is fantastic and version 1.3.1 of WebOS is great. The fact that it runs Linux and has a freely-installable Terminal app and a wicked dev community is a nice bonus too 
Welcome to my blog
November 3rd, 2009Hi everyone,
Having just finished the massive Martin & Co project I’ve decided to stop taking on new freelance work. Since I’m now only working 3 days a week at Simpleweb here in Bristol I’ve now got two weekdays per week off
I decided to use my first free day to build this blog — the photo above I took myself last night at the top of the hill in St Werbughs, and the design I threw together today based around the photo. Do let me know what you think in the comments!
I’m looking forward to having more time to relax — I’m planning on taking a lot more photos and writing more, as well as working on the web cluster project which you’ll hear a lot more about here. I’ll also use this space to blog about some of my improvements to the Zend Framework which we’re using at work… I might even post some music as well.
Right now I’m watching a pretty good BBC documentary about Black Holes, it’s gone a bit “ooh quantum weird” with wobbly music on me, but most impressively it has a fantastic soundtrack by Tunng, if you’ve not listened to them before then check them out.
Anyway enough rambling, hopefully will submit my first “techy” post from work tomorrow if I have a bit of spare time!
Cheers, Luke
