Exploring Leopard with DTrace

My friend and cow-orker Greg Miller has a piece published at MacTech: Exploring Leopard With DTrace.

DTrace is cool. DTrace is awesome. Go read this.

Speed Download for Apple Seeds

Apple provides downloads for OS X version for developers with seed keys. That’s cool.

Apple’s webservers cut off long downloads after twelve hours. When it takes twelve hours and fourteen minutes to download something, that’s not cool. I don’t want to think how many multigigabytes I downloaded before figuring out that twelve-hour cutoff.

Jonathan Wight said on IRC one day, “dude, use Speed Download“. I did. It works. I watched the progress meter at 12 hours. download speed went to zero as expected. A couple of seconds later it cranked back up Fourteen minutes later I had a finished download. That’s cool.

ZeroLink, Rest in Pieces

One thing that made me happy, and was greeted with applause at WWDC, was the news that ZeroLink is gone in Leopard. The linker is now fast enough to make ZeroLink unnecessary.

So what was so bad about ZeroLink? The first problem wasn’t actually ZeroLink’s fault – it was Apple making ZeroLink on by default for new Xcode projects. A common refrain heard from new Mac programmers was “I made a Cool Little Cocoa App, sent it to a friend it won’t work for him. What’s wrong?” ZeroLink.

ZeroLink performed its magic by demand-loading object files, and those object files weren’t included in the application bundle until several Xcode revisions later. So sending an App to a friend (or a reviewer, or a cow-orker) would mean sending them a broken app. Then the programmer would ask for help on a mailing list or IRC, get told to turn of ZeroLink, and then rebuild and re-send. In fact, the Feenode #macdev FAQ has a special section just for ZeroLink.

This was embarrassing and demoralizing, especially for someone new to the platform. New, small projects didn’t benefit from ZeroLink anyway, and you have to have a pretty large program before the time savings is noticeable. Someone with a project that big will have someone intimate with Xcode who would know about ZeroLink, so need to have it on by default.

The second problem was that ZeroLink introduced instability, with its frequent refrain being “I’m getting weird crashes”, which are fixed after turning off zero link. I got paid for a full day’s consulting tracking down a strange C++ operator new overload. The daily smoke test built and ran great, but development versions crashed and burned in weird places. We finally tracked the main difference between the developer builds and the automated builds: ZeroLink. Turned it off, rebuilt, and life was happy ever after. This particular app (which was freaking huge) was broken down into lots of frameworks, so link time wasn’t that much longer than with ZeroLink. (Because of this framework breakdown, I was able to pull some command-line tricks to prevent unnecessary recompilation of other parts of the system, and greatly reduced my turnaround time on a TiBook500 vs the G5-weilding full-timers, but that’s a story for another day.)

Good bye ZeroLink.

NSCoder Night

Chris Hanson and Scott Stevenson are organizing NSCoder Night in the Silicon Valley, a weekly event where Cocoa geeks can hang out for coding and mayhem at a coffee shop or a pub. It sounds like it’ll be a huge amount of fun.

For folks in the Pittsburgh area, Jeff Hunter is organizing DevHouse Pittsburgh thursday the 8th. It’s similar to NSCoder and SuperHappyDevHouse, but in the pittsburgh area. Some of the local CocoaHeads will be there.

Pittsburgh CocoaHeads

After about a year off, Pittsburgh Cocoaheads is going to be starting up again. Second thursday of the month, 7:30 – 9:30 PM, on the CMU campus (Newell-Simon Hall. Room 3000 or 3001. There will be signs pointing the way)

And for folks who don’t know about CocoaHeads, it’s an international Mac Programmer’s group. Pretty much an excuse for Mac programmers to congregate and geek out. Right now we have 20ish chapters in seven countries, two hemispheres, and four continents. Check out CocoaHeads.org for a chapter near you. If there is no local chapter, or if your local chapter hasn’t met in awhile, feel free to drop us a line and become an organizer.

CocoaHeads started in Pittsburgh several years ago when AgentM and I decided to start a Mac programmer’s group because there was nothing in the area. He came up with the name and the logo, and did a lot of evangelizing in the early days. I’m glad AgentM picked the name : I would have come up with something horrible like “Western Pennsylvania Mac Programmer’s Geeking Out And Food Eating Society”, which doesn’t quite have the groovy ring of “CocoaHeads”