Does Anyone Actually Want Serverless?

Cloud computing, and with it most of tech, has been really hot on the idea of "serverless" computing, which is to say, services and applications that are deployed, provisioned, and priced separate from conventional "server" resources (memory, storage, bandwidth.) The idea is that we can build and expose ways of deploying and running applications and services, even low-level components like "databases" and "function execution", in ways that mean that developers and operators can avoid thinking about computers qua computers.

Serverless is the logical extension of "platform as a service" offerings that have been an oft missed goal for a long time. You write high-level applications and code that is designed to run in some kind of sandbox, with external services provided in some kind of ala carte model via integrations with other products or services. The PaaS, then, can take care of everything else: load balancing incoming requests, redundancy to support higher availability, and any kind of maintains on the lower level infrastructure. Serverless is often just PaaS but more: provide a complete stack of services to satisfy needs (databases, queues, background work, authentication, caching, on top of the runtime,) and then change the pricing model to be based on request/utilization rather than time or resources.

Fundamentally, this allows the separation of concerns between "writing software," and "running software," and allows much if not all of the running of software to be delegated to service providers. This kind of separation is useful for developers, and in general runtime environments seem like the kind of thing that most technical organizations shouldn't need to focus on: outsourcing may actually be good right?

Well maybe.

Let's be clear, serverless platforms primarily benefit the provider of the services for two reasons:

  • serverless models allow providers to build offerings that are multi-tenant, and give provider the ability to reap the benefit of managing request load dynamically and sharing resources between services/clients.
  • utilization pricing for services is always going to be higher than commodity pricing for the underlying components. Running your on servers ("metal") is cheaper than using cloud infrastructure, over time, but capacity planning, redundancy, and management overhead, make that difficult in practice. The proposition is that while serverless may cost more per-unit, it has lower management costs for users (fewer people in "ops" roles,) and is more flexible if request patterns change.

So we know why the industry seems to want serverless to be a thing, but does it actually make sense?


Makers of software strive (or ought to) make their software easy to run, and having very explicit expectations about the runtime environment, make software easier to run. Similarly, being able to write code without needing to manage the runtime, monitoring, logging, while using packaged services for caching storage and databases seems like a great boon.

The downsides to software producers, however, are plentiful:

  • vendor lock-in is real, not just because it places your application at the mercy of an external provider, as they do maintenance, or as their API and platform evolves on their timeframe.
  • hosted systems, mean that it's difficult to do local development and testing: either every developer needs to have their own sandbox (at some expense and management overhead), or you have to maintain a separate runtime environment for development.
  • application's cannot have service levels which exceed the service level agreements of their underlying providers. If your serverless platform has an SLA which is less robust than the SLA of your application you're in trouble.
  • when something breaks, there are few operational remedies available. Upstream timeouts are often not changeable and most forms of manual intervention aren't available.
  • pricing probably only makes sense for organizations operating at either small scale (most organizations, particularly for greenfield projects,) but is never really viable for any kind of scale, and probably doesn't make sense in any situation at scale.
  • some problems and kinds of software just don't work in a serverless model: big data sets that exceed reasonable RAM requirements, data processing problems which aren't easily parallelizable, workloads with long running operations, or workloads that require lower level network or hardware access.
  • most serverless systems will incur some overhead over dedicated/serverfull alternatives and therefore have worse performance/efficiency, and potentially less predictable performance, especially in very high-volume situations.

Where does that leave us?

  • Many applications and bespoke tooling should probably use serverless tools. Particularly if your organization is already committed to a specific cloud ecosystem, this can make a lot of sense.
  • Prototypes, unequivocally make sense to rely on off-the-shelf, potentially serverless tooling, particularly for things like runtimes.
  • If and when you begin to productionize applications, find ways to provide useful abstractions between the deployment system and the application. These kinds of architectural choices help address concerns about lock-in and making it easy to do development work without dependencies.
  • Think seriously about your budget for doing operational work, holistically, if possible, and how you plan to manage serverless components (access, cost control, monitoring and alerting, etc.) in connection with existing infrastructure.

Serverless is interesting, and I think it's interesting to say "what if application development happened in a very controlled environment with a very high level set of APIs." There are clearly a lot of cases where it makes a lot of sense, and then a bunch of situations where it's clearly a suspect call. And it's early days, so we'll see in a few years how things work out. In any case, thinking critically about infrastructure is always a good plan.

The Kubernetes Cloud Mainframe

I made a tongue-in-cheek comment on twitter a while back that, k8s is just the contemporary API for mainframe computing., but as someone who is both very skeptical and very excited about the possibilities of kube, this feels like something I want to expand upon.

A lot of my day-to-day work has some theoretical overlap with kube, including batch processing, service orchestration, and cloud resource allocation. Lots of people I encounter are also really excited by kube, and its interesting to balance that excitement with my understanding of the system, and to watch how Kubernetes(as a platform) impacts the way that we develop applications.

I also want to be clear that my comparison to mainframes is not a disparagement, not only do I think there's a lot of benefit to gain by thinking about the historic precedents of our paradigm. I would also assert that the trends in infrastructure over the last 10 or 15 years (e.g. virtualization, containers, cloud platforms) have focused on bringing mainframe paradigms to a commodity environment.


  • clusters are static ususally functionally. I know that the public clouds have autoscaling abilities, but having really elastic infrastructure requires substantial additional work, and there are some reasonable upper-limits in terms of numbers of nodes, which makes it hard to actually operate elastically. It's probably also the case that elastic infrastructure has always been (mostly) a pipe dream at most organizations.
  • some things remain quite hard, chiefly in my mind:
    • autoscaling, both of the cluster itself and of the components running within the cluster. Usage patterns are don't always follow easy to detect patterns, so figuring out ways to make infrastructure elastic may take a while to converse or become common. Indeed, VMs and clouds were originally thought to be able to provide some kind of elastic/autoscaling capability, and by and large, most cloud deployments do not autoscale.
    • multi-tenancy, where multiple different kinds of workloads and use-cases run on the same cluster, is very difficult to schedule for reliably or predictably, which leads to a need to overprovision more for mixed workloads.
  • kubernettes does not eliminate the need for an operations team or vendor support for infrastructure or platforms.
  • decentralization has costs, and putting all of the cluster configuration in etcd imposes some limitations, mostly around performance. While I think decentralization is correct, in many ways for Kubernetes, applications developers may need systems that have lower latency and tighter scheduling abilities.
  • The fact that you can add applications to an existing cluster, or host a collection of small applications is mostly a symptom of clusters being over provisioned. This probably isn't bad, and it's almost certainly the case that you can reduce the overprovisioning bias with kube, to some degree.

Impact and Predictions

  • applications developed for kubernettes will eventually become difficult or impossible to imagine or run without kubernettes. This has huge impacts on developer experience and test experience. I'm not sure that this is a problem, but I think it's a hell of a dependency to pick up. This was true of applications that target mainframes as well.
  • Kubernetes will eventually replace vendor specific APIs for cloud infrastructure for most higher level use cases.
  • Kubernetes will primarily be deployed by Cloud providers (RedHat/IBM, Google, AWS, Azure, etc.) rather than by infrastructure teams.
  • Right now, vendors are figuring out what kinds of additional services users and applications need to run in Kubernetes, but eventually there will be another layer of tooling on top of Kubernetes:
    • logging and metrics collection.
    • deployment operations and configuration, particularly around coordinating dependencies.
    • authentication and credential management.
    • low-latency offline task orchestration.
  • At some point, we'll see a move multi-cluster orchestration, or more powerful tools approach to workload isolation within a single cluster.


Kubernetes is great, and it's been cool to see how, really in the last couple of years, it's emerged to really bring together things like cloud infrastructure and container orchestration. At the same time, it (of course!) doesn't solve all of the problems that developers have with their infrastructure, and I'm really excited to see how people build upon Kubernetes to achieve some of those higher level concerns, and make it easier to build software on top of the resulting platforms.

Programming in the Common Lisp Ecosystem

I've been writing more and more Common Lips recently and while I reflected a bunch on the experience in a recent post that I recently followed up on .

Why Ecosystems Matter

Most of my thinking and analysis of CL comes down to the ecosystem: the language has some really compelling (and fun!) features, so the question really comes down to the ecosystem. There are two main reasons to care about ecosystems in programming languages:

  • a vibrant ecosystem cuts down the time that an individual developer or team has to spend doing infrastructural work, to get started. Ecosystems provide everything from libraries for common tasks as well as conventions and established patterns for the big fundamental application choices, not to mention things like easily discoverable answers to common problems.

    The more time between "I have an idea" to "I have running (proof-of-concept quality) code running," matters so much. Everything is possible to a point, but the more friction between "idea" and "working prototype" can be a big problem.

  • a bigger and more vibrant ecosystem makes it more tenable for companies/sponsors (of all sizes) to choose to use Common Lisp for various projects, and there's a little bit of a chicken and egg problem here, admittedly. Companies and sponsors want to be confidence that they'll be able to efficiently replace engineers if needed, integrate or lisp components into larger ecosystems, or be able to get support problems. These are all kind of intangible (and reasonable!) and the larger and more vibrant the ecosystem the less risk there is.

    In many ways, recent developments in technology more broadly make lisp slightly more viable, as a result of making it easier to build applications that use multiple languages and tools. Things like microservices, better generic deployment orchestration tools, greater adoption of IDLs (including swagger, thrift and GRPC,) all make language choice less monolithic at the organization level.

Great Things

I've really enjoyed working with a few projects and tools. I'll probably write more about these individually in the near future, but in brief:

  • chanl provides. As a current/recovering Go programmer, this library is very familiar and great to have. In some ways, the API provides a bit more introspection, and flexibility that I've always wanted in Go.
  • lake is a buildsystem tool, in the tradition of make, but with a few additional great features, like target namespacing, a clear definition between "file targets" and "task targets," as well as support for SSH operations, which makes it a reasonable replacement for things like fabric, and other basic deployment tools.
  • cl-docutils provides the basis for a document processing system. I'm particularly partial because I've been using the python (reference) implementation for years, but the implementation is really quite good and quite easy to extend.
  • roswell is really great for getting started with CL, and also for making it possible to test library code against different implementations and versions of the language. I'm a touch iffy on using it to install packages into it's own directory, but it's pretty great.
  • ASDF is the "buildsystem" component of CL, comparable to setuptools in python, and it (particularly the latest versions,) is really great. I like the ability to produce binaries directly from asdf, and the "package-inferred" is a great addition (basically, giving python-style automatic package discovery.)
  • There's a full Apache Thrift implementation. While I'm not presently working on anything that would require a legit RPC protocol, being able to integrate CL components into larger ecosystem, having the option is useful.
  • Hunchensocket adds websockets! Web sockets are a weird little corner of any stack, but it's nice to be able to have the option of being able to do this kind of programming. Also CL seems like a really good platform to do
  • make-hash makes constructing hash tables easier, which is sort of needlessly gawky otherwise.
  • ceramic provides bridges between CL and Electron for delivering desktop applications based on web technologies in CL.

I kept thinking that there wouldn't be good examples of various things, (there's a Kafka driver! there's support for various other Apache ecosystem components,) but there are, and that's great. There's gaps, of course, but fewer, I think, than you'd expect.

The Dark Underbelly

The biggest problem in CL is probably discoverability: lots of folks are building great tools and it's hard to really know about the projects.

I thought about phrasing this as a kind of list of things that would be good for supporting bounties or something of the like. Also if I've missed something, please let me know! I've tried to look for a lot of things, but discovery is hard.


  • rove doesn't seem to work when multi-threaded results effectively. It's listed in the readme, but I was able to write really trivial tests that crashed the test harness.
  • Chanl would be super lovely with some kind of concept of cancellation (like contexts in Go,) and while it's nice to have a bit more thread introspection, given that the threads are somewhat heavier weight, being able to avoid resource leaks seems like a good plan.
  • There doesn't seem to be any library capable of producing YAML formated data. I don't have a specific need, but it'd be nice.
  • it would be nice to have some way of configuring the quicklisp client to be able to prefer quicklisp (stable) but also using ultralisp (or another source) if that's available.
  • Putting the capacity in asdf to produce binaries easily is great, and the only thing missing from buildapp/cl-launch is multi-entry binaries. That'd be swell. It might also be easier as an alternative to have support for some git-style sub-commands in a commandline parser (which doesn't easily exist at the moment'), but one-command-per-binary, seems difficult to manage.
  • there are no available implementations of a multi-reader single-writer mutex, which seems like an oversite, and yet, here we are.

Bigger Projects

  • There are no encoders/decoders for data formats like Apache Parquet, and the protocol buffers implementation don't support proto3. Neither of these are particular deal breakers, but having good tools dealing with common developments, lowers to cost and risk of using CL in more applications.
  • No support for http/2 and therefore gRPC. Having the ability to write software in CL with the knowledge that it'll be able to integrate with other components, is good for the ecosystem.
  • There is no great modern MongoDB driver. There were a couple of early implementations, but there are important changes to the MongoDB protocol. A clearer interface for producing BSON might be useful too.
  • I've looked for libraries and tools to integrate and manage aspects of things like systemd, docker, and k8s. k8s seems easiest to close, as things like cube can be generated from updated swagger definitions, but there's less for the others.
  • Application delievery remains a bit of an open. I'm particularly interested in being able to produce binaries that target other platforms/systems (cross compilation,) but there are a class of problems related to being able to ship tools once built.
  • I'm eagerly waiting and concerned about the plight of the current implementations around the move of ARM to Darwin, in the intermediate term. My sense is that the transition won't be super difficult, but it seems like a thing.

Pattern Fragment 2

This is the follow up to Pattern Fragment 0 and Pattern Fragment 1.

After the yoke decreases, in addition to the steeks, there should be 196 stitches in total, or 98 stitches on the front and back of the neck.

Knit the yoke section plain, until it is--in total--3 inches deep. On the front of the sweater, knit 49 stitches (half), cast on 10 steek stitches, and continue knitting round marking the stitches. Knit the next round plan, and then decrease one stitch on either side of the steek, every other round, 21 or 22 times to shape the neck (42 or 44 rounds). Knit plain from here to the end of the sweater. After the first 2-3 inches of decreases, you may choose to space out the decreases more for a gradual slope, though I wouldn't.

Meanwhile, when the yoke is 7.5 inches deep, set aside at least 26 stitches in the middle of the back for back-of-neck-shaping, cast on a 10 stitch steak, and then decrease on alternating sides of the steek over the next inch and a half, until the number of stitches decreased at the front is exactly equal to the number of stitches decreased at the back.

When the yoke is 9 inches deep, in the last round bind off the middle two stitch of both of the armhole steeks, ending with knitting across the back one last time. Turn the work inside out and using a three-needle bind off, join and bind off the shoulders.

Knitting off the Cone

I have, for a long time, done rather a lot of knitting from yarn directly off of cones, which is maybe a bit weird or at least uncommon, so I thought I'd elaborate a bit more:

  • Theoretically a cone of yarn, which often contains at least 250 grams or more of yarn, has fewer breaks in it than you'd have with an equivalent weight of yarn packaged in skeins or balls. This isn't always true, as cones of yarn do have breaks, sometimes, but if you have a construction that doesn't require you break the yarn very much you can probably save a lot of weaving in by knitting off of a cone.
  • Cones of yarn are often not quite ready for use: most often the yarn hasn't received its final wash, which often means that the spinning oil is still in the wool. This is potentially only true for yarn that's undyed or dyed before being spun, and not the case for yarn that's dyed after being spun. It's also likely the case that the yarn will be wound onto the cone slightly tighter than it would be otherwise. The effect is that the yarn will be a bit limp relative to it's final state. The color can also change a bit. You can knit with the unwashed yarn, but know that the final product will require a bit more washing, and the texture can change.
  • Typically the kind of yarn that's available on cones is boring, which is to say that there are less varieties in general but also of different colors. I think this is actually a great thing: knitting in more plain colors and simple smooth yarns draws attention to the knitting itself, which is often my goal.
  • Cones of yarn feel like buying yarn in bulk, and buying yarn by the pound or kilo (!) means that you can really get a feel for the yarn and it's behavior and knit with it for more than one project. Make a few sweaters, or many pairs of socks. See what happens!
  • Because yarn on cones is often used as a method of distributing undyed yarn to dyers in bulk, you can select materials on the basis of fiber content in a way that can be difficult when you also have to balance color considerations.

The clear solution to this problem is, of course, to wind the yarn off the cone into a hank (typically using a niddy nody or similar,) avoid tying the yarn too tightly, soak and wash the yarn gently with wool wash, and then hang it up to dry, and then wind it back into balls. I never do this. I should, but realistically I never do.

How to Write Performant Software and Why You Shouldn't

I said a thing on twitter that I like, and I realized that I hadn't really written (or ranted) much about performance engineering, and it seemed like a good thing to do. Let's get to it.

Making software fast is pretty easy:

  • Measure the performance of your software at two distinct levels:

    • figure out how to isolate specific operations, as in unit test, and get the code to run many times, and measure how long the operations take.
    • Run meaningful units of work, as in integration tests, to understand how the components of your system come together.

    If you're running a service, sometimes tracking the actual timing of actual operations over time, can also be useful, but you need a lot of traffic for this to be really useful. Run these measurements regularly, and track the timing of operations over time so you know when things actually chair.

  • When you notice something is slow, identify the slow thing and make it faster. This sounds silly, but the things that are slow usually fall into one of a few common cases:

    • an operation that you expected to be quick and in memory, actually does something that does I/O (either to a disk or to the network,)
    • an operation allocates more memory than you expect, or allocates memory more often than you expect.
    • there's a loop that takes more time than you expect, because you expected the number of iterations to be small (10?) and instead there are hundreds or thousands of operations.

    Combine these and you can get some really weird effects, particularly over time. An operation that used to be quick gets slower over time, because the items iterated over grows, or a function is called in a loop that used to be an in-memory only operation, now accesses the database, or something like that. The memory based ones can be trickier (but also end up being less common, at least with more recent programming runtimes.)

Collect data, and when something gets slower you should fix it.

Well no.

Most of the time slow software doesn't really matter. The appearance of slowness or fastness is rarely material to user's experience or the bottom line. If software gets slower, most of the time you should just let it get slower:

  • Computers get faster and cheaper over time, so most of the time, as long as your rate of slow down is slow and steady over time, its usually fine to just ride it out. Obviously big slow downs are a problem, but a few percent year-over-year is so rarely worth fixing.

    It's also the case that runtimes and compilers are almost always getting faster, (because compiler devlopers are, in the best way possible, total nerds,) so upgrading the compiler/runtime regularly often offsets regular slow down over time.

  • In the vast majority of cases, the thing that makes software slow is doing I/O (disks or network,) and so your code probably doesn't matter and so what your code does is unlikely to matter much and you can solve the problem by changing how traffic flows through your system.

    For IX (e.g. web/front-end) code, the logic is a bit different, because slow code actually impacts user experience, and humans notice things. The solution here, though, is often not about making the code faster, but in increasingly pushing a lot of code to "the backend," (e.g. avoid prossing data on the front end, and just make sure the backend can always hand you exactly the data you need and want.)

  • Code that's fast is often harder to read and maintain: to make code faster, you often have to be careful and avoid using certain features of your programming language or runtime (e.g. avoiding ususing heap allocations, or reducing the size of allocations by encoding data in more terse ways, etc,) or by avoiding libraries that are "slower," or that use certain abstractions, all of which makes your code less conventional more difficult to read, and harder to debug. Programmer time is almost always more expensive than compute time, so unless it's big or causing problems, its rarely worth making code harder to read.

    Sometimes, making things actually faster is actually required. Maybe you have a lot of data that you need to get through pretty quickly and there's no way around it, or you have some classically difficult algorithm problem (graph search, say,), but in the course of generally building software this happens pretty rarely, and again most of the time pushing the problem "up" (from the front end to the backend and from the backend to the database, similar,) solves whatever problems you might have.

  • While there are obviously pathological counter-examples, ususally related to things that happen in loops, but a lot of operations never have to be fast because they sit right next to another operation that's much slower:

    • Lots of people analyze logging tools for speed, and this is almost always silly because all log messages either have to be written somewhere (I/O) and generally there has to be something to serialize messages (a mutex or functional equivalent,) somewhere because you want to write only one message at a time to the output, so even if you have a really "fast logger" on its own terms, you're going to hit the I/O or the serializing nature of the problem. Use a logger that has the features you have and is easy to use, speed doesn't matter.
    • anything in HTTP request routing and processing. Because request processing sits next to network operations, often between a database as well as to the client, any sort of gain by using a "a faster web framework," is probably immeasurable. Use the ones with the clearest feature set.

Pattern Fragment 1

This is the follow up to Pattern Fragment 0

After all of the shaping for the body of the sweater, you'll have 256 stitches. The goal is to have 196 stitches total for the yoke section, or 98 stitches front and back. This gives me a yoke width of 14 inches, which I know fits me well. Your shoulder width may turn out to be deeply personal, modify as needed to accommodate your personal shoulders.

Put 14 stitches on holders at each underarm, this should be the 7 stitches before and after your round beginning and middle markers. Cast on 10 steek stitches using the backward loop (e-wrap) method above each steek. These are the underarms.

On the next row, after creating the steeks, decrease one body stitch into the first and last steek stitches, and continue these decreases in alternating rows, 7 times (14 total rows), until there are 98 stitches ready for the yoke.

The division between "stitches set aside" and "stitches decreased" at the beginning of the yoke are flexible, as long as you've finished shaping the yoke before its about 2 inches long.

Finished a Sweater

I finished knitting a sweater a bit ago, and it's pretty cool. Some thoughts:

  • The cuffs ended up being a touch too wide, but it's workable. I think this sweater is really good for wearing over an oxford, and as such slightly wider cuffs may be fine.
  • I used the placket / open neck line reminiscent of 1/4 zip sweaters, but chose for the first time to do garter stitch rather than ribbing for the horizontal parts of the plackets, which worked pretty well, though I might choose to execute them differently in the future. Having said that, I think I want to explore different neck shapes.
  • I didn't do any kind of lower body shaping, which is fine, particularly on such a boxy garment, but waist shaping is a good thing that I'd use again in the future.
  • This is the first drop shouldered garment I've made since the knitting hiatus. It was comforting, but I suspect I'll not knit another for quite a while.
  • I'd knit this sweater before using exactly these colors, albeit in a thicker weight yarn, and a few times with different color combinations. It was really fun and familiar.
  • HD Shetland Yarn is pretty awesome. This was the first time I'd used it for non-stranded knitting, and it was great fun to knit.
  • The previous couple of sweaters that I'd made were both knit at about 9 stitches to the inch, and this was about 7 stitches to the inch, which means that it felt like it went really fast. It's wild how we acclimate to things.