Previously I blogged about many concerns that I have about the sorts of examples that Angular sets (deep in its core libraries) and how I feel like it leads to a “pit of failure” when it comes to reliability engineering and performance optimization. In my day job I feel backed into a corner where I have to support Angular application development and have had to become something of the performance expert and performance “officer” against my early advice that we should have picked anything but Angular. In the end of that complaint post, to offer something constructive, I offered some bon mots about what you might do if you were to rebuild Angular from nearly scratch (I called that idea “Project Gawky” if you want to skip to it). At the end of the day though, I’m a pragmatic software engineer. It’s always my job to build my way out of problems, especially solving other people’s problems.

The short story is that I’ve built a growing collection of libraries around what I’ve called the Pharkas Component Framework. It codifies a lot my “Observables-only” best practices into what I hope is a “pit of success” tool that’s easy to slot into existing (“brownfield”) Angular applications and migrate things a component at a time as you can. I think it is incredibly useful out of the box and have been using it to improve performance in production apps for months now. At the very least, I hope these libraries serve as a good example to the Angular ecosystem, whether or not it sees strong adoption outside of production apps that I’m personally charged to “grease the wheels of”.

I thought I would narrate some of the longer story as well. I’m very proud of Pharkas and what it accomplishes as an example to get around what I think are  problems in Angular deep in the core libraries of the framework, but I also feel like I need to provide at least as much motivation and context as I can on why I built this to help answer why anyone should trust Angular libraries written by someone that unequivocally admits to hating working in Angular.

I Picked a Losing Fight With Zone.js

When I last blogged about Angular I was obviously already trying to think of constructive ways to build my way out of the mess. I mentioned these “Project Gawky” ideas in case they sparked someone else to maybe put in the work, because at the time they mostly revolved around replacing or somehow augmenting/extending Angular’s template language compiler. Angular likes to pretend that it doesn’t have a template language “it just uses HTML” and as you would imagine this means that Angular’s (massive) template compilers (there have been several massive rewrites) themselves are somewhat “secretive” in what of its internals are publicly documented. They aren’t really built for easy replacement or augmentation/enhancement. That lack of tools support is the core to why “Project Gawky” was much more of a pie-in-the-sky rewrite idea than a pragmatic solution to offer.

Soon after publicly documenting those thoughts on my blog, but while I was still in the middle of thinking about trying to construct my way out Angular, I got tossed into a massive performance fight where the biggest production app I was working on would just “stall out” for minutes of wall clock time. There was no noticeable network activity, no useful “progress” indication, terrible responsiveness to user interactions (“slow”/”ignored” clicks), and not even a “please wait/processing” beach ball or spinning hour glass: it was just the absolute possible worst user experience and it was making our production users angry.

There wasn’t a clear indication of when the problem started, much less if it was a performance regression specific to any recent code. (There wasn’t even a clear indication of a specific source/cause. The reproduction was “navigate the app randomly for long enough”.) There was some heavy calculation work in an observable pipeline that recently was refactored just a tiny bit, so in terms of hypotheses, and enough evidence that pipeline was shared by enough components on most pages that was my best idea of a place to start. I started in the obvious places of making sure that the pipeline wasn’t over-subscribed, wasn’t leaking subscriptions without unsubscribes, and wasn’t accidentally over-observing to many input events from other pipelines.

I started with a lot of taps and console.logging debugging, and in the middle of that was pointed to RxJS-Spy which is a fantastic debugging tool and I can’t recommend enough. It provides a simple tag operator where you give a pipeline a name, which is a no-op in production builds but in debug builds gives you an entire dev console framework to spy on specific pipelines by name or groups of pipelines by regex. It offers the ability to choose between console.logging and debugger breakpoints. Again, it’s just a great improvement on “tap-style” debugging. Install it today. (I have nothing to do with RxJS-Spy, I just keep recommending it to projects now.)

The more I tagged with RxJS-Spy the more I verified that the app’s observable pipelines didn’t have obvious leaks and were observing things at a pace that seemed reasonable, including the massive possibly expensive calculations I was worried about in my hypothesis. At this point I had easily disproved my hypothesis.

This is the part of debugging that gives everyone nightmares: all of my team’s code is working just as expected. Does that mean the performance issue isn’t in my team’s code?

In just about any other framework I would have already have pulled out “flame graphs” from the Browser’s performance developer tools and been trying to base my hypotheses on real, hard evidence, not just shooting from the hip in the dark or trying to litter the entire code base with console.logs in the hopes that I could guess at performance bottlenecks. In Angular it is really hard to get useful data out of flame graphs for one specific reason: Zone.js.

Zone.js is a supposed “prollyfill” to implement a JS proposed feature that ECMA Technical Committee 39 (TC-39) shot down years ago for being dangerous, confusing, and not generally useful. So far as I’m aware, Angular remains the only “customer” of Zone.js, and today is entirely embedded in the Angular repo. Angular uses Zone.js deeply to power its change detection systems. Zone.js works by monkey patching the entire JS world like a virus or other malware: it infects every Event callback, every Promise, and every RxJS Observable. It plugs in a bunch of its own guts in the middle of every bit of code you try to run in an Angular app.

This “infection” is completely visible in any Angular production flame graph. It changes and impacts every single execution stack in the application. Look at the flame graph and the flames are all Zone.js. You may insert here in your mind an “Everything is fine” meme with the dog labeled Angular and all the flames labeled Zone.js.

Somewhere in those Zone.js flames your code is probably running. Somewhere.

I captured some of these wall clock stalls in the performance tools. I knew to expect most of the flame graphs to be Zone.js nonsense. I assumed with the stalls taking minutes of wall clock time that something not Zone.js should be visible enough in that haystack to make a difference and make it possible to find.

I consistently found no needles in that haystack. I had minutes and minutes of call stacks and the further I dug in the more it was all Zone.js haystack and not a single needle of application code. Was the performance problem entirely Zone.js? I had no good ideas from the glimpses of internal-only Zone.js APIs and source files in the stack traces to tell in any reasonable way whatever it thought it was doing. (I still have no good ideas or answers months later. Zone.js remains a terrifying horror mystery to me.)

At this point in the horror movie (Happy Halloween! I guess you can now guess why I was maybe saving this story for this month; it’s a debugger’s ghost story) several audience members would be shouting at me: Zone.js has a debugger mode and turning it on is buried as a comment line in the Dev environment.ts file in every template-scaffolded Angular application, because they presume you will need it at some point. As a developer with a lot of experience in debugging, I find deep behavior changes between environments spooky. It was at this point where I felt that I was out of debug options and I needed that frightening last option. I cautiously opened that last door.

With Zone.js in that weird debug mode, I could no longer reproduce the pauses and the application performed better than production. đŸ‘» Boo! It’s haunted! You’re going to die! Get out of the house! đŸ‘»

Zone.js Must Die

This absolutely is one of my deepest nightmares as a sometimes “performance expert”: the bad performance is coming from inside the framework itself! The framework acts weirdly different in debug and production environments and it’s the production environment experiencing the worse performance in a way that makes no sense. You can’t debug your way out of the production problem because your debugger can’t reproduce it.

Hyperbolically, I went insane here. I lost my damn mind.

I had hard evidence that Angular was a horror show under the covers and was causing our production users real pain, anguish, and suffering. But unfortunately, I don’t have the power to convince an entire company that the Sunk Cost Fallacy is real and less of a problem than trying to keep sleeping in the haunted horror house because we got such a good deal when we bought it from the previous owners who died of mysterious circumstances that surely were unrelated to why the house was on sale. I’m told to “just do my job” and patch a fix.

That left to me the only “logical” and “pragmatic” realization: Zone.js Must Die.

I suppose in the horror film analogy this is the realization by the final girl that Zone.js really is some sort of serial killer and it is time for her to roll up her sleeves and go on the offense and fight back against that ruthless serial killer.

So I started researching everything I could to murder Zone.js without breaking Angular.

Angular is kind enough to give you the option to boot up with a noop “Zone” and entirely disable Zone.js. Unfortunately, this breaks Angular Change Detection in weird ways and most apps stop functioning at this point if you just switch to the noop â€œZone”.

Angular’s Change Detection apparatus is a direct consequence of Angular’s broken compromises between providing RxJS Observables and then also providing tons of imperative escape hatches. Observables are entirely “push”: they push notifications when changes happen. You shouldn’t need change detection in a pure Observable world, you already have change notification (“for free”), because that is what Observables are. (This is where the “Project Gawky” idea gets most of its promise: with “free” change notifications you can wire it to do some very smart things also “for free”.) But Observables are “hard” and Angular couldn’t commit to them and the resulting worst of both worlds compromise “needs” Change Detection.

That Change Detection uses Zone.js to tell it any time anything happens in the app, ever. Zone.js figures this out by wrapping all the Events, Promises, and Observables in the world that it can find with extra instrumentation. Just to tell Angular “hey, something changed somewhere, I don’t know, maybe” (not even really what changed, certainly not to the specific level of individual Observable pushes). Angular still has to do a ton of work after those Zone.js callbacks to figure out what exactly changed and then from there what to update in the templates/DOM.

Fortunately Angular seems to have actually anticipated this, too, that with Observables you have a “push” based system for notifications already and in theory shouldn’t need change detection at all. It took me something of a deep dive into some of the less well documented parts of Angular, but it turns out the framework indeed has left component developers a “manual stick shift” option for writing components: you can annotate in the Component decorator that the component uses the Change Detection Strategy named “OnPush” and that you will push all change notifications manually.

The “OnPush” Change Detection Strategy does give you an offense strategy to use to fight Zone.js from the bottom-up of an application, and it needs to be from the bottom up: OnPush components do not need to be wrapped in Zones (and generally aren’t, though Zone.js is “viral” in nature and there are no guarantees it doesn’t accidentally infect), which is great. But that also means that OnPush components can only ever use other OnPush components. Components that use the “Default” change detection strategy and need Zone.js to detect their changes can use OnPush components just fine, but not the other way around.

But a “bottom up only” hope in a brownfield application is still a ton of hope to make a noticeable change. A “manual stick shift” option isn’t ideal, but that too gives hope that you have something that you can automate and that you can build an automatic transmission on top of a manual stick shift with software. It’s not pretty, but it is “pragmatic” and it will get the job done.

Introducing the Pharkas Component Framework

To recap: I lost my mind in horror. I decided that Zone.js must die. Then I finally discovered some hope for a “bottom-up solution”.

I realized that I could build it: I could codify my “Observables only” way of building components into a library, and use that library to build a handy “automatic transmission” to replace Zone.js-based Change Detection with something smarter and less compromised (if it sticks to “Observables only”).

Unlike “Project Gawky”, I had a firm place to start to build a useful, reusable library for building (Zone-free) OnPush components in an Observables only way that could provide not just automated push-based change detection to Angular, but even bring in some of the “smarts” ideas of “Project Gawky” and apply them as good defaults. By making them good defaults I hope that my library can build not just a “pit of success” but a “pit of smart success” to the developers that choose to use it. For instance, React took several major versions worth of revisions and refactoring and a lot of code to deliver “concurrent mode” which deprioritizes most DOM work until after idle callbacks such as requestAnimationFrame helping the browser to focus on interactivity over DOM element thrashing. Concurrent mode is still not yet the default in React for several compatibility reasons and needs to be opt-in. I’ve built something similar in my own library for debouncing change notifications to Angular to nice clean requestAnimationFrame time just using Observable schedulers in very little code (it’s probably a lot more documentation than code at this point), and it is default and (simple) opt-out. (While it is at it, the library also takes care of boring Angular administrative trivia such as ngOnInit and ngOnDestroy lifecycle callbacks.)

Overall, I feel like this library has turned into some of the best documented and well-tested open source I’ve had the pleasure to work on. I’m not entirely satisfied with the testing just yet, as I’m waiting for Angular to make the leap to the next major version of RxJS to get some good “marble diagram” timing tests added. Because of that useful default of debouncing to requestAnimationFrame, I need a marble diagram harness that understands and fakes requestAnimationFrame timing, which the next major of RxJS supports out of the box and I wasn’t happy with backports I attempted for the current Angular supported RxJS.

I named this library “Angular Pharkas” and the approach the “Pharkas Component Framework”. This name is a terrible joke, that is possibly only funny to myself. I had lost my mind, remember, and I needed to scrape out whatever sanity I could out of this entire horror situation, and had to get whatever I built into production ASAP to make users happy (and naming is indeed one of the hardest problems in all of computer science). So I named it a joke and filled its README with a few jokes to amuse myself. It’s maybe not the most “professional” approach, but sometimes we need humor in our darkest hours.

To entirely over explain the joke: Freddy Pharkas: Frontier Pharmacist was a 1993 adventure game from Sierra On-Line near the peak of their development golden age. It can be described as the “Blazing Saddles of videogames” and is a joke filled satire of cowboy, Western, and Old West tropes in which the title character just wants to be a respectable, civilized Pharmacist selling prescriptions in a lawless frontier town. (I recall it nearly breaks the fourth wall as hard as Blazing Saddles as well, but it has been a decade easily since I last played it. The comparison is not entirely unearned, for those that have a high opinion of Blazing Saddles.) As someone trying to peddle RxJS best practices in a sometimes lawless-feeling ecosystem, I sometimes feel like a frontier pharmacist when working in Angular. (The terrible pun there being that “Rx” in addition to technically meaning “Reactive Extensions”, which was the original .NET name for its Observables-pattern framework, is also one of the more common abbreviations for the word “prescription” sometimes stylized ℞ and has been used by pharmacists for that word for a long time, from latin “recipe” meaning â€œtake”.)

The Growing Pharkas â€œFamily”

Beyond the base component and the library that provides the core “Pharkas Component Framework“, I’ve been slowly accumulating a lot of ancillary libraries of other open source components and component base classes that make sense to release next to it.

So far the biggest running theme of these other components is providing Angular wrappers for “Vanilla JS” components. There are a number of factors behind this including the sorts of components I’ve needed to work on for my day job’s production apps, navigating which components are “business critical/secret sauce/non-disclosable” versus which seem good candidates to open source (or clean room rewrite as open source in my spare time, because I lost my mind and have done some moonlighting here) because they have no domain specific code, and that the “bottom up” approach to converting to OnPush components especially highlights your “VanillaJS wrapper components” as a key “bottom” that needs conversion early.

I think “Vanilla JS” components (and components from outside frameworks embedded inside Angular) are especially ripe to gain the benefits of OnPush style components: they shouldn’t have any change detection needs because they handle everything internally. Wiring all of a “Vanilla JS” component’s Event handlers, Promises, and even Observables with Zone.js just because it may in very unlikely cases result in a change to detect is possibly the purest example of obviously unnecessary overhead. Zone.js tries not to be that “viral”, and most existing Angular wrapper components know the pain of what that means and all the little things that need to be wrapped in an NgZone.run callback. (Default components using OnPush components don’t need NgZone.run callbacks in my experience, that boundary is handled automatically enough, unlike the “Vanilla JS” boundary.)

I think these Pharkas “family” of “Vanilla JS” wrappers should serve as useful examples of the gains to be made in using OnPush component wrappers in all cases. There should be no doubts that the performance is better in the boundary spaces between Angular and not-Angular. There’s no NgZone injections and no NgZone.run calls. There’s no change detection notifications necessary at all when the component handles all of its own update cycles.

I think they also serve as good, interesting examples of the types of setup and teardown you can do when you think entirely in Observables. I think that’s often one of the things developers complain the most that they need imperative “escape hatches” from Observables for (and why Angular is the bizarre compromise that it is): dealing with the boundaries between components that understand them and those that have more imperative APIs. You can do a lot with Observables if you put your mind to it.

These libraries are also more documentation than code. Some of them are direct drop-in replacements for well known Angular wrapper libraries and I think you’ll find less, easier to understand code than the wrappers that they replace, even before you add in the additional benefits that they simply perform better.

The “demo site” for Pharkas right now is a collection of these “Vanilla JS” components themselves (more than one!) used in a combined “dashboard” with (fake) real time data. I’m incredibly biased here, but I have never seen performance that strong at the “Vanilla JS boundaries” anywhere else in the Angular world. The real time is “fake” but modeled at speeds and amount of data I’ve seen in actual real time dashboards in Production (in Frameworks that are not Angular). There’s definitely no strange and unexpected Zone.js stalls. (The demo site is built in the Angular noop “Zone” so truly has no Zone.js at all even in accidental fallback.)

All of this is MIT licensed open source, and I encourage everyone to at least dig in and glance at the source and maybe try to learn from it, if nothing else, even if you don’t think you need any of these libraries in your own production work.

Aside: Observable “State Management”

The “Pharkas Component Framework” is agnostic to how you build Observables, it only mandates that you use Observables.

There are a lot of options in Angular, many inspired by the React ecosystem’s Redux (in my opinion without understanding the reasoning behind Redux, but that is a complaint for another blog post) such as NgRx, NgXs, and more. Pharkas doesn’t care if you use any or none of them. It works well with them. It works well without them.

In my company’s production we already have a wild hodge podge of all of the above. In my own development and prioritization I’ve taken a “without them” approach I currently call “lots of small Observables” which may be possibly called “Atomic Observables” in analogy to the React “counter-Redux” term “Atomics”. Today I don’t have a library to offer on this pattern. I see it as simply a pattern and an “obvious one” at that, so I don’t think it needs a library at all. (I might even describe it today as a “natural” pattern of Observable building, implying it is the NgRx/NgXs/et al of the world that is perhaps a bit “unnatural”.) It is on my TODO list to eventually try to write some better documentation on that pattern in the hopes it sparks joy in some developers.

At one point I thought Pharkas “needed” a state management answer or to be a little bit less state management “agnostic” to be a “real” Angular Observable library (thanks NgRx/NgXs et al for that bit of impostor syndrome), but I decided YAGNI (you aren’t going to need it) and yeeted it out in early versions and have no regrets having done so.

Should You Use Pharkas?

I probably wouldn’t if I were you. You likely have no good reason to trust my claims at face value and doubt my credentials. I probably wouldn’t even build this library, much less offer to maintain it if I convinced my day job to avoid Angular like the plague, which I have tried to convince them multiple times. I don’t blame you to be skeptical.

Highlighted and self-aware summary of previous sections:

I scratched my own itch here. I solved some critical production problems that needed solving ASAP, somehow or another. I did what I had to do. This blog post isn’t a plea to use this work. I have made promises that I think you would see clear performance gains and kinder, gentler developer experience if you to do that, but I don’t expect you to take my word for it.

What I would like? Please learn from it! It’s a handy, easy to explore MIT-licensed Open Source repository. If there’s one particular takeaway here: use OnPush components everywhere you can! This truly is a bottom up initiative. It needs to be “grass roots” in Angular, because it is not the default. Component developers (especially those wrapping “Vanilla JS” components) should start leaning OnPush component by their own default choice. I hope no one else experiences the debugging ghost story đŸ‘» I did to the same extent and it truly is as rare as it seems in Angular that more people don’t call Angular the “haunted house framework” or worse, but after having experienced that every library I see in Angular I now evaluate on “does it use OnPush components?”. You don’t need Pharkas to build OnPush components. I think Pharkas makes it very easy to do that, and adds some nice “automatic transmission” and smarts on top of it, so I would recommend taking a look using it to build your next components, but again my plea here is only for using OnPush components, I don’t care how you get there (“manual stick-shift” or not).

I hope I have set a good example here.

Happy Halloween, and good luck if you are an Angular developer. đŸŽƒ