discoveryd Clusterfuck

I usually keep things fairly clean on this site. I have a simple metric: would I be embarrassed if my Mom read this post? As you’ve probably guessed from the title, this post is going to be different.

So, Mom, it’s time to stop reading. I’m pissed off and you know how I get when that happens.

In case you’re wondering what I’m talking about, look at this shit. A network process using 100% of the CPU, WiFi disconnecting at random times, and names, names (1), names (2), names (4). All caused by a crappy piece of software called discoveryd.

I started reporting these issues early in the Yosemite beta release and provided tons of documentation to Apple engineering. It was frustrating to have a Mac that lost its network connection every few days because the network interfaces were disabled while waking from sleep (and there was no way to disable this new “feature”.)

Regardless of the many issues people were reporting with discoveryd, Apple went ahead and released it anyway. As a result, this piece of software is responsible for a large portion of the thousand cuts. Personally, I’ve wasted many hours just trying to keep my devices talking to each other. Macs that used to go months between restarts were being rebooted weekly. The situation is so bad that I actually feel good when I can just kill discoveryd and toggle the network interface to get back to work.

Only good thing that’s come of this whole situation is that we now have more empathy for the bullshit that folks using Windows have suffered with for years. It’s too bad that Apple only uses place names from California, because OS X Redmond would be a nice homage.

It’s no secret in the tech community that discoveryd is the root cause of so many problems. There are even crazy workarounds. With so many issues, you’d expect some information from Apple explaining ways to mitigate the problems.


The only explanation I can come up with for this astounding lack of information is that there’s some mid-level product manager at Apple who’s covering their ass. I hope this person who’s responsible for withholding advice feels good about themselves, because the rest of us hate them with the burning passion of a thousand suns. Being stingy with knowledge in an engineering organization is a fucking stupid career move.

To give you an idea of how helpful a tiny piece of information is towards people’s productivity, let me give you a simple example that’s already saved me hours of frustration.

For months, I’ve seen bullshit like this in Bonjour:


That shows the xScope service on the Mac that provides data for the Mirror on iOS. In that screenshot, the service is being shown as available on three devices: one with just an IPV6 address, one with no IP addresses, and one with a duplicate IPv6 address and a valid IPv4 address. The name “CedarX” was the only way I could find to prevent names from incrementing (and breaking things that use the host name of that device.)

The “funny” thing is that this Mac is running the latest version of 10.10 with fixes for “WiFi issues”. And after tweeting about it in frustration, I got this response:

I followed Hendrik’s advice and guess what? No more network issues.

Bonjour keeps a cache that’s shared amongst devices on the network. This is so that if the device is asleep, another one that’s awake can provide the necessary information. I suspect that a device running an older version of discoveryd poisoned this cache. For some reason, the invalid cache information couldn’t be corrected by a newer version of the software which screwed things up in the first place.

But this is all just conjecture because Apple hasn’t written that fucking tech note.

This situation also shows another important aspect of the discoveryd clusterfuck: this code is all over the place. It’s in use by iOS, OS X and presumably whatever is running on the Apple Watch. As such, any one of those devices can poison Bonjour for everything else on your network.

This workaround is fairly simple if you’re on a home network where you have direct physical access to the all the devices. But as we all know, wireless networking is essential in places like an office, an airport or a coffee shop. Good luck rebooting everything in that kind of environment. And what happens when someone running an older version of OS X connects to that network and poisons it? Time to reboot!

You also can’t rely on software updates to fix everything: I have both an Airport Express and Apple TV that are no longer receiving fixes. Having to buy new hardware because of crappy software adds insult to injury.

Ironically, these issues are most likely to affect Apple’s best customers. The more devices you have, and the longer you have them, the more likely you are to get an unstable network. The only advice I can offer is to restart your entire network.


Flare on Sale

Flare 2, our Mac app for photographers that was awarded Best of 2014, is currently half price as a part of the Mac App Store’s Amazing Photo + Video promotion.

In addition, the app was recently updated with German and Japanese localizations. The app continues to be a showcase for good design on Yosemite.

We also continue to add new effects using iCloud. I love using Flare Effects on iOS when I post photos to my Instagram account.

For all the latest info about this award-winning app, be sure to check out the Flare Tumblr.


A lot can happen in fifteen years, especially on the web. At the turn of the millennium, many of us were coming to terms with the dynamic nature of a new medium that connected our world. I was honored to be a part of this collection of thoughts and reflections of that time.

I’m a firm believer of moving forward in your work and not relying on past accomplishments. The best way to find the path into the future is to look for clues from where we’ve been. A collection of thoughts from people I admire is priceless.

And before you dismiss this as information that’s only relevant for “web designers”, look at how your apps rely on web infrastructure to do something meaningful. Then think about how difficult it is to build an interface that works well on all screen sizes. These are the same things we struggled with as the web entered adolescence.

Twitterrific Improvements

Great things are happening to Twitterrific these days. My favorite feature is doing drafts, which can really help out when you need to do tech support on Twitter! The changes to muting/muffling are also welcome additions. We even gave you a new way to shoot yourself in the foot with regular expressions :-)

And contrary to common belief, I didn’t have anything to do with this besides being a beta tester. Sean Heber is heading up the development work these days, so if you love these changes as much as I do, be sure to let him know!

China Attacks

Robert Graham built a tool to analyze the traffic causing the DDoS attack on GitHub. He then used it to prove that the machine is “located on or near the Great Firewall of China”.

One has to wonder when politicians will take these virtual attacks as seriously as physical ones. As Robert points out, this attack is against a key part of the United States’ Internet infrastructure. What would we do if China took out all the Interstate highways leading into California?