Lasik post-op

Two days ago I underwent Lasik surgery to correct my nearsightedness. It went as well as could be expected, and I’m currently seeing 20/20 without glasses or contacts. There is a little bit of hazy ghosting around bright objects, but that’s supposed to go away as my corneas heal.

First, the place where I had it done, LasikPlus, is first-class in every respect. They understand customer experience, and do everything to make the experience, including coughing up around $4K, as pleasant as it can possibly be. And my doctor, Bruce January, M.D., had a positive energy that was so infectious that it inspired confidence. The staff also did a great job explaining just what will happen, including trying to explain what it will feel like. The thing is, that only goes so far. So here are my impressions.

The first step in the process is cutting a flap in your cornea’s surface to expose the main part of the lens. There are two separate machines involved, so they have you lay down on a small (comfortable!) table that pivots between two machines. The first machine is where they place a circular device on the eye to hold it still.

operating room
I’m getting ready for the first part of the procedure to start.

Before this is done, some numbing drops are placed in your eyes, so there is no pain. You are told that you will feel it pressing on your eyeball, and that while there won’t be any pain, it will feel a little weird. That’s an understatement! After the device is on your eye, they move you a few feet to the second machine, which does the actual cutting of the cornea using a femtosecond laser. This is where it gets trippy.

You’re staring up and see several very bright white lights, but of course, you can’t blink. When they have you lined up, the machine presses down hard on the aforementioned circular device, and sure, it feel strange having that much pressure on your eyeball. But is even stranger is that you go blind in that eye! From bright white lights to black in a split second! Then you start seeing all sorts of colored patterns moving around. If you ever pressed against your closed eyes when you were a kid and saw the resulting visual effects, it’s sort of like that, but 100 times more intense. I saw spots of different colors that moved around randomly, leaving a trail of dots behind them. And while the visual show was interesting, the whole eyeball pressure thing was getting more and more uncomfortable. I’m not sure of the elapsed time; it was probably less than 30 seconds. But it felt a lot longer! When it was done, the pressure released, and the white lights reappeared. Now it was time to be wheeled back to the first machine, and repeat for the second eye. This time I had a much better idea as to what to expect, and while it was equally uncomfortable, it seemed to go more quickly.

This was the view on the monitor as I was about to have the flap cut into my cornea

Now it was time to get up and walk to the machine that actually reshaped the lenses. It was odd – I could sort of see where I was going, but felt quite a bit disoriented after the previous procedure. The operating room assistant guided me over, and I laid down for part two.

This time there was no discomfort; nothing pressing on the eye, just a small device to keep you from blinking. They told you to just keep focused on the green dot in the middle, while the red lights around it danced and blinked. After a few seconds of blinking it sounded like someone turned on a vacuum cleaner, and the red lights got more intense. The green dot turned into a green patch as the laser etched the lens. Then there’s the smell – you’ve smelled burning hair, right? Well, it’s pretty close to that. I don’t know why I was surprised, since I knew that the whole point of this procedure was to have a laser burn away parts of your lens to re-shape it, but smelling it brought home the reality of what was going on.

The whole process lasted only a few seconds. The smell went away, the vacuum sound stopped, and the green light returned to a dot. Then I saw what looked like a small brush going across my eye. This was the surgeon replacing the corneal flap over my eye. My wife was watching this on the monitors and said it looked like the doctor was smoothing wallpaper. Oh, I didn’t mention that the whole procedure area is viewable from the waiting area, including monitors that show what the doctor is seeing. Just one more thing that showed that they put a lot of thought into the whole experience. The photos here were all taken by my wife Linda while I was undergoing the procedure.

The view on the monitor during the second half of the procedure

Repeat with the other eye, and done! When I got up, I could see clearly enough, although everything had a fuzziness to it. Off to the side room where they give your eyes a quick once-over, repeat the instructions to you for applying the various drops, and we’re done!

post-surgery goggles
Wearing the protective goggles over my very bloodshot eyes 10 minutes after the procedure

I put on the sunglasses they give you, and got in the car for the ride home. Even with sunglasses and my eyes closed, it was uncomfortably bright outside. I kept my eyes closed for the whole ride home, only opening when we arrived. By now the numbing drops were beginning to wear off, and my eyes were watering like crazy. They were also beginning to burn a bit, and soon reminded me of the time I was cutting jalapeño peppers and absent-mindedly rubbed my eyes! Every so often my eyes would get uncomfortable and I’d open them a bit, only to have tears come gushing down my cheeks! It was clear that my eyes were not very happy! I did end up going through a lot of tissues that day!

They advise you to keep your eyes closed for several hours, and recommend that you take a nap. They give you some Tylenol PM to help you sleep, but that didn’t do anything at all for me. I have some over-the-counter sleep aid pills that I use when flying overseas, so I took a couple of those, and slept for the next 5 hours. When I awoke, my eyes felt better, although still a bit scratchy. I kept the drops up, and tried to keep my eyes closed as much as possible.

The next morning I awoke to much clearer vision. Bright areas had a soft halo around them, but that’s to be expected as the cornea heals. I kept up with the drops, as my eyes would start to feel a bit scratchy if I went too long without them. I had my day-after exam, and all was fine.

eye bruising
Some bruising is visible the day after surgery

So 24 hours after having my eyes zapped by lasers I was able to return to working, which requires staring at a screen. The trick is to limit it to 20 minutes at a time, after which I put in more eyedrops and get up to walk around and let my eyes focus on other things for a few minutes. And yes, this post was written in small chunks to give my eyes some rest.

Some post-Lasik thoughts:

As is common with people my age, I need reading glasses. Before the surgery, when I was wearing my contacts and needed to see something up close, the readers were necessary. However, when I removed my contacts I could see perfectly well up close. This was handy when I would awake in the morning and want to set an alarm on my phone for, say, 5 minutes of snoozing. Since the surgery I can’t read my phone when I pick it up in the morning! Guess I’ll have to keep a pair of readers on my nightstand.

Somewhat related to this, when I rolled over to say good morning to my wife, I couldn’t see her very clearly, either. This was far more troubling to me. I guess I had taken it for granted that I would always be able to see her when we woke up. This will take some getting used to. I’m hoping that as my eyes heal, this will not be as severe. I’m not sure the convenience of not having to wear contacts is worth losing this.


I have two major updates to my senses this week: my eyes and ears are both getting an upgrade. On Wednesday, I am undergoing Lasik surgery to correct my nearsightedness, and on Friday I am getting hearing aids.

I have been nearsighted since I was around 10 years old, and have worn glasses or contacts ever since. Here’s a photo of me from way back when:

school photo with glasses
My 7th grade school picture. What a nerd!

So I’ve spent most of my life with poor natural vision, but I’ve always been able to correct it so that I could see just fine. My hearing, though, is another story. When I was 18, I had just come home after an evening out, just beating an oncoming thunderstorm. As I walked from my car to the house it started pouring, and I made it inside without getting too soaked. Now I’ve loved thunderstorms since I was a little kid; all that power fascinated me. So once inside the house, I stood at the front screen door, watching the lightning, and counting the delay of the thunder to determine how far away it is. After a few minutes I remember seeing lightning flashes on both my left and right that were within a mile, and thinking that this must be the center of the storm. Right then, I saw an incredibly bright flash that was accompanied by a simultaneous loud thunderclap. It took a few seconds until my eyes could see again after the bright flash, and I stood there in a bit of shock and wonderment, as I knew that the strike had to have been very close. A few moments later I felt a tap on my shoulder, and I turned around to see my mother talking to me. I say that I saw her talking, because I couldn’t hear a thing she was saying. I then noticed that I couldn’t hear the rain or thunder or anything else!

The next day we went outside to discover that the lightning had struck a tree about 5 feet from the front door where I was standing. It had gone down the tree, and then jumped the gap between the tree and a grounded power line going into the house. This was evidenced by the hole in the side of the house, and a matching burnt patch of bark and wood on the tree.

After a day or so I was able to hear a little bit over the loud ringing in my ears, and a few days later was pretty much back to normal. I didn’t really think about this again until a few years ago when I took a hearing test. I’ve had a hissing tinnitus in my ears for several years, and I noticed it was getting worse. The hearing test showed a very sharp decline in the higher frequencies. In the charts below, a person with normal hearing would have all the points in the grey band along the top. As you can see, mine drop off severely after mid-range frequencies.

hearing test results
My hearing test results.

I thought that this could have been the result of too much loud music; after all, I do love to crank up good songs loud! But the audiologist said that too much loud noise over time would result in all frequencies losing sensitivity. My pattern suggested some hearing trauma, and asked me about any events in my history that I could remember. I told him about the lightning story, and he confirmed that this was the sort of damage pattern you might expect from a trauma like that.

So what does this mean, in practical terms? It means that I have a harder time understanding higher-pitched voices, such as women and children. My poor wife has to endure me asking her to repeat what she said all the time! And even with male voices, most consonant sounds are in the higher frequencies, so I have often have trouble understanding men, too. It also means that I miss things like birds singing and other delicate sounds of nature.

I tried hearing aids a few years ago, but the technology at the time hadn’t progressed enough to make a significant improvement for me, so I just lived with limited hearing. But I went back recently to try the latest technology, and it was amazing! Everything sounded so different! It will take a while to get used to them, of course, but I hope that once I’m acclimated to them, I will be able to hear what I’ve been missing for so many years.

The Lasik procedure will give me the ability to see without corrective lenses, and that will be wonderful, of course. But I’ve always been able to see well, so after the procedure I won’t be experiencing anything new. It will make my life a bit easier, but not richer. But since I’ve lived most of my life without being able to hear correctly, I’m really excited for all the new experiences that my hearing aids will make available to me that were simply not possible for me to enjoy before.

Handling Unstructured Data

There have been a lot of changes to the Scheduler in OpenStack Nova in the last cycle. If you aren’t interested in the Nova Scheduler, well, you can skip this post. I’ll explain the problem briefly, as most people interested in this discussion already know these details.

The first, and more significant change, was the addition of AllocationCandidates, which represent the specific allocation that would need to be made for a given ResourceProvider (in this case, a compute host) to claim the resources. Before this, the scheduler would simply determine the “best” host for a given request, and return that. Now, it also claims the resources in Placement to ensure that there will be no race for these resources from a similar request, using these AllocationCandidates. An AllocationCandidate is a fairly complex dictionary of allocations and resource provider summaries, with the allocations being a list of dictionaries, and the resource provider summaries being another list of dictionaries.

The second change is the result of a request by operators: to return not just the selected host, but also a number of alternate hosts. The thinking is that if the build fails on the selected host for whatever reason, the local cell conductor can retry the requested build on one of the alternates instead of just failing, and having to start the whole scheduling process all over again.

Neither of these changes is problematic on their own, but together they create a potential headache in terms of the data that needs to be passed around. Why? Because of the information required for these retries.

When a build fails, the local cell conductor cannot simply pass the build request to one of the alternates. First, it must unclaim the resources that have already been claimed on the failed host. Then it must attempt to claim the resources on the alternate host, since another request may have already used up what was available in the interim. So the cell conductor must have the allocation information for both the original selected host, as well as every alternate host.

What will this mean for the scheduler? It means that for every request, it must return a 2-tuple of lists, with the first element representing the hosts, and the second the AllocationCandidates corresponding to the hosts. So in the case of a request for 3 instances on a cloud configured for 4 retries, the scheduler currently returns:

Inst1SelHostDict, Inst2SelHostDict, Inst3SelHostDict

In other words, a dictionary containing some basic info about the hosts selected for each instance. Now this is going to change to this:

        [Inst1SelHostDict1, Inst1AltHostDict2, Inst1AltHostDict3, Inst1AltHostDict4],
        [Inst2SelHostDict1, Inst2AltHostDict2, Inst2AltHostDict3, Inst2AltHostDict4],
        [Inst3SelHostDict1, Inst3AltHostDict2, Inst3AltHostDict3, Inst3AltHostDict4],
        [Inst1SelAllocation1, Inst1AltAllocation2, Inst1AltAllocation3, Inst1AltAllocation4],
        [Inst2SelAllocation1, Inst2AltAllocation2, Inst2AltAllocation3, Inst2AltAllocation4],
        [Inst3SelAllocation1, Inst3AltAllocation2, Inst3AltAllocation3, Inst3AltAllocation4],

OK, that doesn’t look too bad, does it? Keep in mind, though, that each one of those allocation entries will look something like this:

    "allocations": [
            "resource_provider": {
                "uuid": "9cf544dd-f0d7-4152-a9b8-02a65804df09"
            "resources": {
                "VCPU": 2,
                "MEMORY_MB": 8096
            "resource_provider": {
                "uuid": 79f78999-e5a7-4e48-8383-e168f307d098
            "resources": {
                "DISK_GB": 100

So if you’re keeping score at home, we’re now going to send a 2-tuple, with the first element a list of lists of dictionaries, and the second element being a list of lists of dictionaries of lists of dictionaries. Imagine now that you are a newcomer to the code, and you see data like this being passed around from one system to another. Do you think it would be clear? Do you think you’d feel safe proposing changing this as needs arise? Or do you see yourself running away as fast as possible?

I don’t have the answer to this figured out. But last week as I was putting together the patches to make these changes, the code smell was awful. So I’m writing this to help spur a discussion that might lead to a better design. I’ll throw out one alternate design, even knowing it will be shot down before being considered: give each AllocationCandidate that Placement creates a UUID, and have Placement store the values keyed by that UUID. An in-memory store should be fine. Then in the case where a retry is required, the cell conductor can send these UUIDs for claiming instead of the entire AllocationCandidate. There can be a periodic dumping of old data, or some other means of keeping the size of this reasonable.

Another design idea: create a new object that is similar to the AllocationCandidates object, but which just contains the selected/alternate host, along with the matching set of allocations for it. The sheer amount of data being passed around won’t be reduced, but it will make the interfaces for handling this data much cleaner.

Got any other ideas?

Rigid Agility

The title of this post points out the absurdity of the approach to Agile software development in many organizations: they want to use a system designed to be flexible in order to quickly and easily adapt to change, but then impose this system in a completely inflexible way.

The pitfalls I discussed in my previous blog post are all valid. I’ve seen them happen many times, and they have had a negative impact on the team involved. But they were all able to be fixed by bringing the problem to light, and discussing it honestly. A good manager will make all the difference in these situations.

But the most common problem, and also the most severe, is that people simply do not understand that Agile is a philosophy, not a set of things that you do. I could go into detail, but it is expressed quite well in this blog post by Brian Knapp.

The key point in that post is “Agile is about contextual change”. When things are not right, you need to be able to change in response. Moreover, it is specifically about not having a set of rigid rules defining how you work. Unfortunately, too many managers treat Agile practices as if they were magical incantations: just say these words, and go through these motions, and voilà! Instant productivity! Instant happy developers! Instant happy clients!

Agile practices came about in response to previous ways of doing things that were seen as too rigid to be effective. The name “Agile” itself represents being able to change and adapt. So why do so many managers and companies fail to understand this?

In most cases, this misunderstanding is greatest when adopting these practices is mandated from the upper levels of management, instead of developing organically by the teams that use it. In many cases, some VP reads an article about how Agile improved some other company’s productivity, and decides that everyone in their company will do Agile, too! I mean, that’s what leadership is all about, right? So the lower-level managers get the word that they have to do this Agile thing. They read up on it, or they go to a seminar given by some highly-paid consultants, and they think that they know what they have to do. Policies and practices are set up, and everyone has to follow them. Oh, wait, you have some groups in the company who don’t work on the same thing? Too bad, because the CxO level has decreed that “everyone must do these same things in the same way”.

Can you see how this practice misses the whole point of being Agile? (and why I started this series with a blog post about Punk Rock?) A team needs to figure out what works for them and what doesn’t, and change so that they are doing more of the good stuff and less (or none) of the bad. And it doesn’t matter if other teams are running things differently; you should do what you need to be successful. In an environment of trust, this happens naturally.

Unfortunately, when Agile is imposed from the top down, trust is usually never considered as important, and certainly not the most important aspect of success. And when teams start to follow these Agile practices in this sort of environment, they may experience some improvement, but it certainly will not be anything like they had envisioned. Teams will be called “failures” because they didn’t “do agile right”. Managers then respond by reading up some more, or hiring “agile consultants“, in order to figure out what’s wrong. They may decide to change a thing or two, and while it may be slightly better, it still isn’t the nirvana that was promised, and it never will be.

Unfortunately, too many people who are reading this and nodding their heads in recognition are stuck in a rigid company that is afraid to trust its employees. All I can say to you is do what you can to make things better, even if things still fall short. And in the longer term, “contextual change” is probably a term you need to apply to your employment.

Agile Pitfalls

So your team is adopting Agile practices? Maybe even your whole company? Your managers and their managers are all talking about it, and the wonderful future it will bring, with gains in productivity and developer happiness. But while it can be exciting and productive when done correctly, unfortunately too many do not understand what it means to be Agile. They’ve probably read a few articles about it, and know words like Scrum and Kanban and Velocity, and now think they understand Agile. They set out to change their teams to be Agile, and the team begins to estimate user stories, do regular standups, and divide development tasks into 2-week sprints. They’re agile now, right?

Not even close.

Agile, first and foremost, is about trust. Trust in the developers on the team to create quality software. Trust in the product managers to state the business’s needs accurately. Trust in management that the additional transparancy required for agile development will not be used to criticize performance in the future. Trust that bringing a problem to the forefront will be appreciated instead of perceived as an attempt to blame. Trust that if events happen to change the situation, that the team will make the adjustments required. Trust that blame will never be the goal.

If any member of the team feels that their honesty and openness will be used against them in any way, they will respond by hiding things and disengaging from the team. Sure, they’ll still appear to be doing things the new way, but they won’t be forthcoming about problems they are encountering, and will instead paint a positive but unrealistic picture of their progress. Managers need to be aware of this, and back it up by rewarding openness.

So while it is true that adopting some or all of the practices that fall under the term “agile” can improve your team’s software development, there are plenty of pitfalls to watch out for. While some of these pitfalls are the result of not understanding how agile practices are supposed to work, most stem from mistrust and fear that the transparency will be used against them at some point in the future, such as performance reviews. I’ve listed several, in order from the least impactful to the most:

Note: I’m using the term “standup” to refer to the regular meeting of the team responsible for the work being done. Some places call it a “scrum”, but scrum is actually one particular set of agile practices, with a standup being one of them. I prefer to call it “standup” for two reasons: first, it emphasizes that everyone should be standing. That may sound silly, but it does wonders for keeping things brief and on-point. Second, if you’re familiar with the sport of rugby, a scrum is visually the opposite of how your team should look.

rugby scrum
Now *this* is a scrum!

Many of these pitfalls may seem trivial, but together they add up to reduce any gains you might expect to make by implementing Agile practices.

“Gaming” story point estimation

What I mean by “gaming” is inflating the number of points you estimate for your story so that it looks like you’re doing more (or more difficult) work than you actually are. This happens a lot in environments where team members feel that their performance evaluations will be based on their velocity. So when it comes time to estimate story points, these developers will consistently offer higher numbers, and argue for them by overstating the expected complexity. This behavior pre-dates Agile development; see this Dilbert cartoon from 1995 for a similar example. It’s human nature to want to look like you’ve accomplished a lot, especially when your potential raise and/or promotion is dependent on it. Again, managers can help reduce this by never using completed story points as a metric for evaluation, or even praising someone for completing a “tough” story. It’s a team effort, and praise should be for the entire team.

Using standup for planning

This is common in the early stages of development, when people are still figuring things out. During standup, someone mentions an issue they are having, and another person chimes in with some advice. A discussion then ensues about various approaches to solve the issue, with the pros and cons of each being argued back and forth. Before you know it, 20 minutes has gone by, and you’re still on the first person’s report.

If something comes up during standup that requires discussion longer than a minute or so, it should be tabled until after standup. Write it down somewhere so it isn’t forgotten, and then move on. After standup, anyone interested in discussing that issue can do so, and the rest can go back to what they were doing.

Treating story point estimates as real things

Who hasn’t reviewed a requirement, and thought “this isn’t so difficult”, only to find once you try to make that change, a lot of other things break? That’s just a reality when working with non-trivial systems. In an atmosphere of trust, that developer would share this news at the next standup (at the latest), so that everyone knows that the original estimate was wrong. But sometimes developers are made to feel that if it takes too long to finish a story that was estimated as fairly easy, that would be seen as failure, and be held against them. In such an environment, many developers might hide this information, and struggle with the problems by themselves, instead of feeling safe enough to share the difficulty with their team.

Not having a consistent definition of “done” for Kanban

We all know what the word “done” means, right? Well, it’s not so clear when it comes to software. Is it done when the unit tests pass? When the functional tests pass? When it is merged into the master branch? When it is released into production?
Each team should define what they mean by “done”, and apply that consistently. Otherwise, you’ll have stories that still need attention marked as “done”, and that will make any measure of velocity meaningless.

Using standup to account for your time

This is one of the most common pitfalls to teams new to scrum. During standup, you typically describe what you’ve been working on the previous day, what you plan to work on today, and (most importantly) if there is anything preventing you from being successful. This serves several purposes: to keep people from duplicating efforts by knowing what others are working on, and to catch those inevitable problems before they grow to become disasters.

But if your manager (or someone else with a higher-level role) is in the standup, many team members can feel pressure to list every single thing that they worked on, or meetings they went to, or side tasks that they helped out on… none of which has any bearing on the project at hand. Especially if they have been working on a single thing, while others in the team have been working on several smaller tasks. It just sounds like they are goofing off, or not being as productive as other members of the team. If you are the manager of a team and you notice team members doing this, it’s important to reassure them that you’re not tracking how they spend their time at standup. That would also be a good time to reinforce to the team what standup should be about. Again, if that trust is not there among the team members, standup will become a waste of people’s time.

Rigid adherence to practices

All of the above can and do contribute to failures in teams adopting agile practices. But this last one is far worse than all of the others combined. It’s bad enough to merit its own blog post.