We reduced our iOS app launch time by 60%(doordash.engineering)
doordash.engineering
We reduced our iOS app launch time by 60%
https://doordash.engineering/2023/01/31/how-we-reduced-our-ios-app-launch-time-by-60/
214 comments
In short, they are using a third party library (they have not named it though) that accounts to 40% of the app launch time and they deferred loading of this library to later point!
Thanks, it's astonishing how many teams make this mistake, simply putting some hungry library into the code to solve some story without thinking much further about the overall implications
I'm like 90% confident that it's their crash tracking or analytics library :P
Edit: It's a framework from Salesforce called "ServiceCore". In case you were wondering it decided that it was necessary to request a list of all frameworks in a static constructor so it could find one that contains a certain class of theirs that does bundle-relative image loading. Pro tip, don't do this.
Edit: It's a framework from Salesforce called "ServiceCore". In case you were wondering it decided that it was necessary to request a list of all frameworks in a static constructor so it could find one that contains a certain class of theirs that does bundle-relative image loading. Pro tip, don't do this.
How can you tell which framework it is?
I pulled open the app and looked for frameworks with approximately 9 static initializers, one of which called into NSBundle. ServiceCore was the one that matched.
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I don't know if it's still the case, but some third party libraries are required to run on launch.
I worked on a an app where the Facebook login library took 600ms to load, and was required to run on launch.
I worked on a an app where the Facebook login library took 600ms to load, and was required to run on launch.
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If it's a crash manager, you have to load it early if you want to catch early crashes. Still, only the Mach exception handler really needs to be installed. I wrote an in-house crash reporting SDK based around PLCrashReporter and the whole thing loads in under 20 ms on a modern device.
200 ms is insane for an SDK, any SDK. Our company had that as its target cold start time to first interaction across all of our apps and it's something we watched religiously as part of launching new app versions.
200 ms is insane for an SDK, any SDK. Our company had that as its target cold start time to first interaction across all of our apps and it's something we watched religiously as part of launching new app versions.
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Most work on making things faster is to give a shit.
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I wish they’d name the third party library.
I thought the same, especially after said-3rd-party didn't respond to their request for a lazy initializer.
But then I'm thinking, what does it matter? Is this the only selfish 3rd-party library out there?
Maybe better than: "Here is a bad library to link against", the takeaway is "all 3rd-party libraries are a potential liability."
But then I'm thinking, what does it matter? Is this the only selfish 3rd-party library out there?
Maybe better than: "Here is a bad library to link against", the takeaway is "all 3rd-party libraries are a potential liability."
> "all 3rd-party libraries are a potential liability."
Yup. Even if they are responsive today, doesn't mean they will be, tomorrow.
My views on The Dependapocalypse are not usually welcome, in modern discussions of software strategy.
Not exactly sure why they are using string(describing:) in ship code. I suspect the architecture may need a bit of a look-see.
I only use it in debug tracking. It's the reflection API, and that's not really something I'd consider for runtime. Sort of like using exceptions for branching. It works, but your results may not be optimal.
UPDATED TO ADD: I did think of one place I might use it (actually, the ".description" computed property), and that's in a "one-off" bit of code that may be doing something like figuring out how to deal with some JSON I parsed, or reading stored prefs. Otherwise, I've usually figured out other ways to deal with it. One advantage I have, is I seldom use third-party libraries, and can actually go into my modules, and tweak them to serve the frontend better (in fact, I just did exactly that, this morning).
Yup. Even if they are responsive today, doesn't mean they will be, tomorrow.
My views on The Dependapocalypse are not usually welcome, in modern discussions of software strategy.
Not exactly sure why they are using string(describing:) in ship code. I suspect the architecture may need a bit of a look-see.
I only use it in debug tracking. It's the reflection API, and that's not really something I'd consider for runtime. Sort of like using exceptions for branching. It works, but your results may not be optimal.
UPDATED TO ADD: I did think of one place I might use it (actually, the ".description" computed property), and that's in a "one-off" bit of code that may be doing something like figuring out how to deal with some JSON I parsed, or reading stored prefs. Otherwise, I've usually figured out other ways to deal with it. One advantage I have, is I seldom use third-party libraries, and can actually go into my modules, and tweak them to serve the frontend better (in fact, I just did exactly that, this morning).
I've fixed similar performance problems, typically the reason people use this is because it's a convenient way to get the name of the type or because they are logging it somewhere and get the default Swift behavior.
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I don't think we can conclude from this that there's anything wrong with the third-party library people... there are tradeoffs and doordash probably isn't their only user. Doordash may not be paying or contributing either. Maybe the 3rd-party library people could have sent a basic "Thanks for the feature request" reply for the sake of politeness... But lacking that polish doesn't make them "selfish".
> Maybe the 3rd-party library people could have sent a basic "Thanks for the feature request" reply for the sake of politeness... But lacking that polish doesn't make them "selfish".
Why would they? I mean, when was the last time you got a "thank you" message by opening a feature request to any open source project bug tracker?
Why would they? I mean, when was the last time you got a "thank you" message by opening a feature request to any open source project bug tracker?
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I am going to guess it is google maps. Here is a non-exhaustive list of frameworks they have in the app:
- Google Maps
- Persona
- InstaBug
- CardVerify
- SendBird
- Stripe
- Google Sign-in
- PhoneNumberKit
- Riskified
- VGS
"The third-party framework in question had a total of nine module initializers". I would guess it is probably google maps simply because they tend to do things like this and IIRC you have to setup in the startup even if you use the map later.
Might have missed some frameworks but I think I got most of them.
Edit: maybe not google maps... it seems that 200ms added to any app that uses it would be fairly noticeable. Perhaps one of the lesser used ones.
- Google Maps
- Persona
- InstaBug
- CardVerify
- SendBird
- Stripe
- Google Sign-in
- PhoneNumberKit
- Riskified
- VGS
"The third-party framework in question had a total of nine module initializers". I would guess it is probably google maps simply because they tend to do things like this and IIRC you have to setup in the startup even if you use the map later.
Might have missed some frameworks but I think I got most of them.
Edit: maybe not google maps... it seems that 200ms added to any app that uses it would be fairly noticeable. Perhaps one of the lesser used ones.
Not Google Maps (which by the way has 51 initializers) :)
out of curiosity, how did you find out the frameworks used in the app?
I'm with you, but I also think that discussion about specific tools often is wrongly prioritized over discussion of general principles. The lesson should be "always profile your programs, and be especially wary of third-party dependencies" rather than "avoid this specific library at all costs."
I'm assuming they also understandably don't want to start a flame war, where their specific criticism of the library is going to be taken to mean "this library is always bad, do not use it, even if its effect on performance is negligible in your case."
I'm assuming they also understandably don't want to start a flame war, where their specific criticism of the library is going to be taken to mean "this library is always bad, do not use it, even if its effect on performance is negligible in your case."
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I'd put my money on either the Facebook SDK or a crash/bugreporting tool. They say it's important to UX, and both of those are (for sign-in-with-FB, or bugreporting).
It would be nice if DoorDash cared as much about their web app performance as they do their native app performance. Their web app perf is abysmal. Pathetically slow. Clicking takes seconds to see a response in the UI.
Oh my God, how did they do this? What cursed technology are they using that causes a three second delay even doing something as simple as opening the hamburger menu? It's infuriating.
Opening the menu launches a WebAssembly virtual machine for their Docker images to build and run to return the appropriate options /s
In all seriousness though, the tech industry is an immense contributor to global warming because of inefficient software which uses large quantities of energy and necessitates the creation of massive quantities of e-waste as older machines are unable to provide an adequate user experience for extremely computationally heavy designs.
Extremely inefficient software which is necessary for everyday tasks also means only the latest hardware from China/Taiwan is competitive. Bad software is a geopolitical and national security risk.
In all seriousness though, the tech industry is an immense contributor to global warming because of inefficient software which uses large quantities of energy and necessitates the creation of massive quantities of e-waste as older machines are unable to provide an adequate user experience for extremely computationally heavy designs.
Extremely inefficient software which is necessary for everyday tasks also means only the latest hardware from China/Taiwan is competitive. Bad software is a geopolitical and national security risk.
> the tech industry is an immense contributor to global warming because of inefficient software
A quick Google search reveals that different sources suggest data centers are responsible for something between 0.2% and 3% of global CO2 emissions. (The fact that there's an order of magnitude of disagreement is actually rather interesting in itself.)
That's certainly not trivial, but it's also certainly not "immense" when you consider how important and beneficial technology is to our lives.
Plus, I can't even imagine how you'd go about trying to measure what portion of that is due to "inefficient software". Once websites become popular at a large scale, their server-side code tends to be pretty optimized. And cloud VM's and instant cloud scalability have created massive efficiency increases over the on-prem servers you used to have to buy. And newer ARM chips are so much more energy-efficient than Intel.
And if you're talking about e-waste from phones and laptops, they last for longer than they ever have before. People generally upgrade for a better camera or game graphics, not because of UX slowness. Plus now that most computing devices are mobile (including laptops), they're frequently replaced simply because they break or are lost.
A quick Google search reveals that different sources suggest data centers are responsible for something between 0.2% and 3% of global CO2 emissions. (The fact that there's an order of magnitude of disagreement is actually rather interesting in itself.)
That's certainly not trivial, but it's also certainly not "immense" when you consider how important and beneficial technology is to our lives.
Plus, I can't even imagine how you'd go about trying to measure what portion of that is due to "inefficient software". Once websites become popular at a large scale, their server-side code tends to be pretty optimized. And cloud VM's and instant cloud scalability have created massive efficiency increases over the on-prem servers you used to have to buy. And newer ARM chips are so much more energy-efficient than Intel.
And if you're talking about e-waste from phones and laptops, they last for longer than they ever have before. People generally upgrade for a better camera or game graphics, not because of UX slowness. Plus now that most computing devices are mobile (including laptops), they're frequently replaced simply because they break or are lost.
> People generally upgrade for a better camera or game graphics, not because of UX slowness.
Not my experience. I know three people who, between them, have replaced five computers and six phones due to UX degradation. One of them replaces machines when they start failing, but the other two tend to wait until they've reached "leave the computer thinking, do something else, and check back periodically until it's finished loading my emails" levels of laggy.
Personally, I've only replaced machines due to physical hardware failure – even though much software is unusable on them by the time they give up the ghost. (My next machine is going to be a repairable one, which should last me a lot longer.) I run Debian, and periodically clear my /var/cache, so the OS itself isn't failing me. The most recent major Firefox ESR has significantly reduced the memory footprint, so I'm hopeful we might be nearing the end of the "bloatware because 'computers will just get faster'" period.
Not my experience. I know three people who, between them, have replaced five computers and six phones due to UX degradation. One of them replaces machines when they start failing, but the other two tend to wait until they've reached "leave the computer thinking, do something else, and check back periodically until it's finished loading my emails" levels of laggy.
Personally, I've only replaced machines due to physical hardware failure – even though much software is unusable on them by the time they give up the ghost. (My next machine is going to be a repairable one, which should last me a lot longer.) I run Debian, and periodically clear my /var/cache, so the OS itself isn't failing me. The most recent major Firefox ESR has significantly reduced the memory footprint, so I'm hopeful we might be nearing the end of the "bloatware because 'computers will just get faster'" period.
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In this context we're talking about client-side waste, right? Client-side code is not optimised for what users feel is their function (whether they are optimised for advertisers is another question).
The rise of webtech-for-"apps" is the only reason I can't still work on a 4GB laptop and feel like that's a luxurious amount of memory (8 feels cramped now, in fact), so wasteful software drives e-waste and higher resource use in computer manufacturing, too.
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> I can't even imagine how you'd go about trying to measure what portion of that is due to "inefficient software". Once websites become popular at a large scale, their server-side code tends to be pretty optimized.
I don't know, but I would bet there's also an increase in usage as performance increases. When software is fast you use it more frequently and for more things.
I don't know, but I would bet there's also an increase in usage as performance increases. When software is fast you use it more frequently and for more things.
reminded me of this article that talks about the environmental cost of bloated mobile apps: https://www.emergetools.com/blog/posts/CostOfAByte
I hate inefficient software for its human cost. Add up the wasted human time and it's whole lifetimes lost to thoughtless software.
I'll bet if you calculated the carbon "cost" of a human life and did the math on the wasted human time it would be higher than the incremental electricity cost of the datacenter or amortized manufacturing cost of the phone or whatever else you're worried about. But I feel much worse about the wasted life for its own sake, personally.
I'll bet if you calculated the carbon "cost" of a human life and did the math on the wasted human time it would be higher than the incremental electricity cost of the datacenter or amortized manufacturing cost of the phone or whatever else you're worried about. But I feel much worse about the wasted life for its own sake, personally.
This seems so out of left field to me. Geopolitics and global warming are so far down the list of concerns from inefficient and slow software.
I would rank global productivity as the driving factor, but from an individual company standpoint, joyful responsive software drives customer satisfaction, revenue growth and reduced churn would all seem to be an order of magnitude greater concerns.
Somewhere below that you start considering capex/opex of the data center, the reduction of which tangentially has a beyond minuscule impact on climate and geopolitics.
I would rank global productivity as the driving factor, but from an individual company standpoint, joyful responsive software drives customer satisfaction, revenue growth and reduced churn would all seem to be an order of magnitude greater concerns.
Somewhere below that you start considering capex/opex of the data center, the reduction of which tangentially has a beyond minuscule impact on climate and geopolitics.
Quick look at the network tab shows two network requests, they are launched in parallel and take 250ms on my end.
The stunning part is one of these is to get a string of text that is displayed in a banner that is only visible if you scroll in the menu (like, at the very bottom). You could easily defer this call to happen once the menu is open and have 0 impact on the UX.
The other call, I have no idea what it does, but is launched both when you open and close the menu.
The stunning part is one of these is to get a string of text that is displayed in a banner that is only visible if you scroll in the menu (like, at the very bottom). You could easily defer this call to happen once the menu is open and have 0 impact on the UX.
The other call, I have no idea what it does, but is launched both when you open and close the menu.
It’s likely a tracking event. I work for an e-commerce company and tracking menu open/close is a big metric.
But why would these be network calls that block the UI?
Analytics calls don't generally block the UI. Must be the call the fetch the string. Or incompetence.
Prevent the user from blocking the tracking?
Are such metrics even meaningful? It sounds like metrics-for-the-metrics-god, useless unactionable information.
The problem is you often don’t know what metrics are meaningful until after the fact.
Like, if new order starts drop by 4% while traffic remains constant, what happened? If that happens, you might want to see if people are using the menu more because something got harder to find on the page.
I doubt anyone is looking purely at menu opens as a metric, unless maybe trying to reduce it. But for ongoing funnel and ad hoc investigations it could be useful. So you collect it.
The obvious answer is sampling rather than collecting for every user, but then you get into complicated statistics about required sample sizes if you want to correlate multiple actions across tech and demographics. Again, easier to just collect it all.
Like, if new order starts drop by 4% while traffic remains constant, what happened? If that happens, you might want to see if people are using the menu more because something got harder to find on the page.
I doubt anyone is looking purely at menu opens as a metric, unless maybe trying to reduce it. But for ongoing funnel and ad hoc investigations it could be useful. So you collect it.
The obvious answer is sampling rather than collecting for every user, but then you get into complicated statistics about required sample sizes if you want to correlate multiple actions across tech and demographics. Again, easier to just collect it all.
Do many oversized tests but carefully avoid testing the test themselves because why would you? Would you test the test of the test too? etc? Someone might one day conclude the tests cost more than they are worth but it wouldn't be the ones hired to inflict them.
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Maybe there is a conference somewhere that includes instacart, the reddit redesigners, twitter, facebook messenger and instagram and they all share their tips for making their interfaces as slow as molasses.
That’s laughable. Twitter is one of the best web apps I use both on desktop and in iOS while Reddit is pathetic. They’re not in the same galaxy.
Twitter's web app was at that conference doing a workshop on ways to disable right-click Open in new tab.
Twitter's web version is actually using React Native for web - one of the types of technology people often expect will perform poorly
Trying to use it while logged out in a private session on mobile is an absolute joke. After the page loads, you get the "Download the mobile app" nag that takes up half the screen and that you have to dismiss. As often as not, as I'm trying to dismiss that, the "Sign in with Google" nag pops up over it and I accidentally navigate away to their SSO flow, have to hit back, wait patiently for the popup that pops up over the popup, dismiss them both, then just read the text on the page that I intended to read.
Credit where credit is due though, up until a month or two ago I'd then also get hit with the Quora-esque "Make an account to continue" nag that blocked reading if God forbid I scrolled too far down the page. When geohotz went to Twitter, I recall him saying if nothing else he would get rid of this garbage anti-feature and sure enough I've not seen it since.
Credit where credit is due though, up until a month or two ago I'd then also get hit with the Quora-esque "Make an account to continue" nag that blocked reading if God forbid I scrolled too far down the page. When geohotz went to Twitter, I recall him saying if nothing else he would get rid of this garbage anti-feature and sure enough I've not seen it since.
GP mentioned slowness, not UX choices (on which I agree). They’re two different (but slightly overlapping) issues: incompetence and policy.
They choose to make the experience suck for anonymous users, but no one chooses to have the app react after 3 seconds on an iPhone 13 (looking at you, Reddit)
They choose to make the experience suck for anonymous users, but no one chooses to have the app react after 3 seconds on an iPhone 13 (looking at you, Reddit)
On my iPhone SE the Twitter web app becomes laggy after performing a few searches and scrolling through a few lists.
Sure my phone is kinda old, but I don’t believe it has to be like this ...
Sure my phone is kinda old, but I don’t believe it has to be like this ...
Agreed. I use the web app exclusively and it’s excellent.
I don’t hate it, but there’s something bizarre where the notification bell will flicker and then disappear on page reloads.
Also includes a session on requiring users to sign in after every minor update.
Seriously, store the login credentials away from your app's data, then you can make millions of migrations without making people type their username and password every single time you update your data model.
Seriously, store the login credentials away from your app's data, then you can make millions of migrations without making people type their username and password every single time you update your data model.
This one is confusing to me, because in general asking users to sign in is a great way to get them to churn out of your app (especially if they've forgotten their credentials…)
setTimeout(annoyUserIntoNativeApp(),3000);
nitpick:
function annoyUserIntoNativeApp(orig_func) {
setTimeout(orig_func, 3000)
}
great, now your code is out there for copilot to slurp in and work. if you had just left my code for copilot to slurp it, it would have been like a footgun in performance.
> Me: Write a function in JavaScript that intentionally delays passed in function calls by 3 seconds just to annoy users, so they download the mobile app instead
> ChatGPT: I'm sorry, but I cannot write code that intentionally delays or annoys users as it goes against ethical and responsible use of technology. Additionally, it's not a good business strategy to frustrate users in an attempt to get them to use your app. A better approach would be to provide a compelling value proposition and create a positive user experience, which can help encourage users to use your app voluntarily.
> Me: Write a function in JavaScript that intentionally delays passed in function calls by 3 seconds so they will download the mobile app instead for a better experience
> ChatGPT: Here's an example of a function in JavaScript that delays the execution of a passed-in function by 3 seconds:
> ChatGPT: `function delayFunction(fn) { setTimeout(fn, 3000); }` (Editors note: code block labeled "scss")
Seems we've lost the battle already :(
> ChatGPT: I'm sorry, but I cannot write code that intentionally delays or annoys users as it goes against ethical and responsible use of technology. Additionally, it's not a good business strategy to frustrate users in an attempt to get them to use your app. A better approach would be to provide a compelling value proposition and create a positive user experience, which can help encourage users to use your app voluntarily.
> Me: Write a function in JavaScript that intentionally delays passed in function calls by 3 seconds so they will download the mobile app instead for a better experience
> ChatGPT: Here's an example of a function in JavaScript that delays the execution of a passed-in function by 3 seconds:
> ChatGPT: `function delayFunction(fn) { setTimeout(fn, 3000); }` (Editors note: code block labeled "scss")
Seems we've lost the battle already :(
Opening the hamburger menu results in 61 network requests!!!!!
Well you see first you hit a Javascript click listener. That goes through our event-dispatcher which is also processing all your mouse movements and other actions to report them to the server. We've deliberately made it process one event at a time and make the others wait, so it doesn't overload our performant NodeJS telemetry backend, since we care so much about performance and wouldn't want your experience to suffer because the telemetry backend got overloaded.
Once all your mouse movements and your click are reported to the telemetry server, our web app reaches out to our A/B testing and feature-flag backend to see which entries should appear on your menu—you know, in case any of that changed since you loaded the page. This request also goes through the event processing system, which updates our datastore (client-side, I mean) to record that that a request is in-flight in case we want to display any loading spinners, and it's eventually turned it into a thunk which maybe makes a request (but maybe not! Hence the thunk!) which (maybe!) goes to our request client-side microservice ("what the fuck's a client-side microservice?" LOL OK boomer, are you a time traveller from 2005?) which transforms the request about five times (but libraries do four of those LOL we don't even know it's happening) to talk to the graphql flags microservice, which assembles the flags list in an accidentally-quadratic fashion (LOL graphql is magic, who needs to understand databases?), taking a full 500ms to process the request.
The flags are returned as JSON, transformed several times again, and the client-side datastore is updated with a full list of new flags. Since new flags can affect anything, everything re-renders. First, we need to update the shadow DOM, but to do that....
[... five paragraphs later ...]
And then your hamburger menu is on the screen!
Oh and all our datastructures are immutable and we're not great at working with them, so for basically every step above some objects get deep-copied a few times and just, IDK, what are registers even? Client- and server-side both. For safety! Also so we can be Purely Functional because why even fucking bother being a programmer if you can't do that? Like literally just die if you're not writing eighty HOFs a day. You have no idea how elegant all this code is. So elegant.
Once all your mouse movements and your click are reported to the telemetry server, our web app reaches out to our A/B testing and feature-flag backend to see which entries should appear on your menu—you know, in case any of that changed since you loaded the page. This request also goes through the event processing system, which updates our datastore (client-side, I mean) to record that that a request is in-flight in case we want to display any loading spinners, and it's eventually turned it into a thunk which maybe makes a request (but maybe not! Hence the thunk!) which (maybe!) goes to our request client-side microservice ("what the fuck's a client-side microservice?" LOL OK boomer, are you a time traveller from 2005?) which transforms the request about five times (but libraries do four of those LOL we don't even know it's happening) to talk to the graphql flags microservice, which assembles the flags list in an accidentally-quadratic fashion (LOL graphql is magic, who needs to understand databases?), taking a full 500ms to process the request.
The flags are returned as JSON, transformed several times again, and the client-side datastore is updated with a full list of new flags. Since new flags can affect anything, everything re-renders. First, we need to update the shadow DOM, but to do that....
[... five paragraphs later ...]
And then your hamburger menu is on the screen!
Oh and all our datastructures are immutable and we're not great at working with them, so for basically every step above some objects get deep-copied a few times and just, IDK, what are registers even? Client- and server-side both. For safety! Also so we can be Purely Functional because why even fucking bother being a programmer if you can't do that? Like literally just die if you're not writing eighty HOFs a day. You have no idea how elegant all this code is. So elegant.
This is hilarious and sarcastic, but there's a hint of reality here. Overly Complex Engineering is a fashionable (and evidently lucrative) technical discipline now, and is almost expected as the default. If you get an interview question "design a web frontend and backend to do X" and you say "Easy, a single LAMP server can do this," it's likely you're not getting the job.
Sarcastic, but I didn't put anything in I thought entirely implausible (and some of it's straight-up normal; I cut off because there was too much normal remaining, actually, and I didn't feel like writing it all out—we still had to take a trip down into the frontend framework's state machine, and back out again!). Looks like others dug into the page and posted their findings, and my made-up bit about telemetry isn't even that far off, LOL—god, Web is a shit-show. But wasting everyone's time with this crap pays the bills....
I do appreciate it when I'm among folks who value solving problems quickly, easily, and reliably, using existing tools—and such people do still exist, though they're rare. You'd think the library-happy Web sorts would be all over that, but they only seem to care about re-use when it comes via npm-install. Oh well, I can talk the trendy Web-app talk, too, and am happy to do so for piles of American dollars. It's not my money getting tossed in a bonfire.
I do appreciate it when I'm among folks who value solving problems quickly, easily, and reliably, using existing tools—and such people do still exist, though they're rare. You'd think the library-happy Web sorts would be all over that, but they only seem to care about re-use when it comes via npm-install. Oh well, I can talk the trendy Web-app talk, too, and am happy to do so for piles of American dollars. It's not my money getting tossed in a bonfire.
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How any of these developers can call themselves engineers and still look themselves in the mirror is beyond me. An engineer's job is to design the most efficient structure in as little time, and cheap manner as possible that still produce a reasonable and satisfactory result. What all modern web apps have in common is that they cut all corners on development time prior to release to then be forced to optimize the hell out of the mess afterwards in perpetuity. A simple tech stack would accomplish the same tasks with minimal extra initial development time and effort, but would remain performant for a very long time.
They use tons and tons of third party trackers and advertising brokers for populating parts of the page.
They have broken sha512 subresource integrity links on the page.
The site produces no less than 11 samesite cookie misuse warnings.
5.71MB compressed. 520 requests to load the page.
Clicking on a store performs another 224 requests. Loads another 449kb.
Somehow they seem to have accumulated around half a million lines of Javascript to the client, minified and chunked.
They have broken sha512 subresource integrity links on the page.
The site produces no less than 11 samesite cookie misuse warnings.
5.71MB compressed. 520 requests to load the page.
Clicking on a store performs another 224 requests. Loads another 449kb.
Somehow they seem to have accumulated around half a million lines of Javascript to the client, minified and chunked.
Do you mean the hamburger menu or the hamburger menu? :)
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You should hope they don’t pay attention to their web app, since the vast of majority of web sites/apps from big companies seem to only get slower every time a developer touches it. Major redesign? Expect major slowdown at least half of the time.
I recently got back into posting videos to YouTube after ~7 years. Can’t fucking believe how slow the video upload UI has become. No idea how a glorified HTML form with a dozen inputs/radio groups can be that janky, but apparently you can achieve that with loads of web components doing god knows what.
I recently got back into posting videos to YouTube after ~7 years. Can’t fucking believe how slow the video upload UI has become. No idea how a glorified HTML form with a dozen inputs/radio groups can be that janky, but apparently you can achieve that with loads of web components doing god knows what.
Even worse: Every time I order something from a restaurant online, only the first line of the address goes to the delivery driver.
Every. Single. Time. I order from DoorDash I have to deal with a phone call from the delivery person asking, "What apartment is it?" Or worse, living somewhere with a gate code. Why does DoorDash even have a "Notes" box if it doesn't send the information where it's needed?
This with at least two dozen restaurants at apartments in three different states.
Every. Single. Time. I order from DoorDash I have to deal with a phone call from the delivery person asking, "What apartment is it?" Or worse, living somewhere with a gate code. Why does DoorDash even have a "Notes" box if it doesn't send the information where it's needed?
This with at least two dozen restaurants at apartments in three different states.
The backend story is still being prioritized for this task
The cynical part of me thinks that the bad web app is intentional. They can get much more data from you if you use the app, so they want that to be the best experience. All others should be bad enough that you will only use it if there is no other way to give them your money.
I am not disagreeing that they shouldn't focus on their web app, too, but I assume they look at how often the mobile app is used versus web app and are just prioritizing for user base. If more people used web, I'm sure it would get more love.
They really need to look at counterfactuals though - if our webapp were better how many people would use it. The fact that a mediocre site with a better alternative (the app and competitors) doesn't get much traffic should hardly play into the calculation at all.
Unlike HN users, supermajority of population is perfectly fine downloading and using an app. I would even say, opening a browser, going to a website, potentially logging in is more friction than “sliding down and typing doordash to open the app”.
That's fine. I don't have a horse in the app vs website race. What's important to note though is that you are doing the thing I'm preaching. Hammering the idea home:
- The (probabilistic) consequences of your actions are what determine the success of your business. E.g., given <improve shitty website> we <won't increase sales>.
- Current usage metrics matter for time allocation only insofar as they serve the former point.
It's fine to say that users like apps therefore you don't need a decent website. What's not fine is the post I responded to -- the shitty site doesn't have users, so we won't improve it. That's a dangerous thought pattern because it silently substitutes something easily measured for the value you need and tends to cause people to conflate the two. (maybe the author was thinking something more nuanced, but as written it's still a good opportunity to highlight the issue)
- The (probabilistic) consequences of your actions are what determine the success of your business. E.g., given <improve shitty website> we <won't increase sales>.
- Current usage metrics matter for time allocation only insofar as they serve the former point.
It's fine to say that users like apps therefore you don't need a decent website. What's not fine is the post I responded to -- the shitty site doesn't have users, so we won't improve it. That's a dangerous thought pattern because it silently substitutes something easily measured for the value you need and tends to cause people to conflate the two. (maybe the author was thinking something more nuanced, but as written it's still a good opportunity to highlight the issue)
If we add another metric into our decision-making - the percentage of users that have already downloaded the app and stagnating user growth (realistically, it has slowed down since most of people have already either ordered a take out or decided they never will), it doesn’t make sense to add resources into improving a UX that wouldn’t even grow.
Generally I agree with you, but when we focus on specific business use case, it’s harder to convince the stakeholders to work on projects that obviously have lower user engagement.
Generally I agree with you, but when we focus on specific business use case, it’s harder to convince the stakeholders to work on projects that obviously have lower user engagement.
Convenience is the most effective way to get people to abandon software freedom.
You care about software freedom, I do, but end users? Not really. When you’re in business of trying to increase your revenue, largely focusing on theoretical-ethical issues while your competition doesn’t will just drive you out of business. That’s probably when the legislation needs to come into play to even out the field. Whether that needs to be legislated is a different question though.
More likely it's just a different team of people building it, and one cares more about performance than the other.
Just checked, they use React. React has set web performance back decades.
In a smartphone-dominated world, you're lucky there's any webapp at all.
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I know this isn't the point, but I suffer bad connections all the time. I'm so used to a click taking 5 seconds.
Anyways, I do agree with your statement.
Anyways, I do agree with your statement.
Impressive improvement, but is mobile app startup time that important after a certain threshold? I'm not a mobile dev.
If the flame graph extends over the entire startup time, then I'd estimate it to be around 600-700ms (wish they gave the numbers rather than the percentage) which already sounds very nice as a user. If it was like 5 seconds then it would be amazing.
Furthermore, I'm assuming that this only affects when the app is initially started instead of when it is already running in the background or navigating between screens, which is why I feel the linked article on why latency matters in tfa doesn't really support it.
I'm curious about what metrics mobile developers use to prioritize tasks.
If the flame graph extends over the entire startup time, then I'd estimate it to be around 600-700ms (wish they gave the numbers rather than the percentage) which already sounds very nice as a user. If it was like 5 seconds then it would be amazing.
Furthermore, I'm assuming that this only affects when the app is initially started instead of when it is already running in the background or navigating between screens, which is why I feel the linked article on why latency matters in tfa doesn't really support it.
I'm curious about what metrics mobile developers use to prioritize tasks.
I generally lead teams to move quickly to get products usable, deliver the most important features to feed the business, then go back and start optimizing things like launch times.
The DoorDash app is feature stable as far as I can tell as an infrequent user. It makes sense to have the team invest into small optimizations for experience and speed. Much better than letting idle hands start redesigning things that aren’t broken or doing new features for the sake of doing more things.
Also, a 600ms launch time on a high-end phone could be a 5s launch time for someone using a cheap, old phone. Optimizations are most noticed by the lower end of your userbase’s hardware.
The DoorDash app is feature stable as far as I can tell as an infrequent user. It makes sense to have the team invest into small optimizations for experience and speed. Much better than letting idle hands start redesigning things that aren’t broken or doing new features for the sake of doing more things.
Also, a 600ms launch time on a high-end phone could be a 5s launch time for someone using a cheap, old phone. Optimizations are most noticed by the lower end of your userbase’s hardware.
Apple recommends 400ms for startup time because that's how long the app open animation takes. It's also hard to tell from just one flamegraph how long it will really take in prod, that's why the percentages are nice to use. I've mostly used percentiles like p95 to track and prioritize mobile perf work. 600ms on one phone could be 2s on older hardware with other factors slowing it down, but it depends on the distribution of doordash users.
I actually came across the 400ms number in a 2019 WWDC talk while researching the topic! It said 100ms of that time was delegated to the iOS system for setup, leaving 300ms for whatever your app does.
Granted the 100ms section included System Interface - DYLD3 (dynamic linking) as part of it, which includes the 200ms portion that was optimized in tfa so I don't know how accurate that 100-300 breakup is.
The talk also says to avoid dynamic library loading during launch to improve time which is interesting, as it suggests there's an alternative, which may or may not be what Doordash did here.
Granted the 100ms section included System Interface - DYLD3 (dynamic linking) as part of it, which includes the 200ms portion that was optimized in tfa so I don't know how accurate that 100-300 breakup is.
The talk also says to avoid dynamic library loading during launch to improve time which is interesting, as it suggests there's an alternative, which may or may not be what Doordash did here.
Using dlopen is generally not a performant option unless you are doing it off the startup path.
For Doordash I'd say it doesn't matter if the app opens in 700ms or 7000ms. Hungry people are willing to wait a little to order their food.
But then again: How did this get so bad in the first place? I mean, yeah, premature optimization and stuff ... but ...
>One of the biggest immediate standouts was the time we spent on Swift protocol conformance checks (checking if a type conforms to a protocol), but why?
Correct: But why? Why would you do this in a static typed language? Conformance checks should be a rare exception.
>Architectural principles like the single responsibility principle, separation of concerns, and others, are key to how we write code at DoorDash.
Oh, OK, architecture astronautics at play, I guess. Sorry, but you can separate concerns and all that other stuff without ending up with what looks like a dynamic typing system.
/rant (I'm hungry)
But then again: How did this get so bad in the first place? I mean, yeah, premature optimization and stuff ... but ...
>One of the biggest immediate standouts was the time we spent on Swift protocol conformance checks (checking if a type conforms to a protocol), but why?
Correct: But why? Why would you do this in a static typed language? Conformance checks should be a rare exception.
>Architectural principles like the single responsibility principle, separation of concerns, and others, are key to how we write code at DoorDash.
Oh, OK, architecture astronautics at play, I guess. Sorry, but you can separate concerns and all that other stuff without ending up with what looks like a dynamic typing system.
/rant (I'm hungry)
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There are some tried-and-true principles that have worked since the dawn of computing.
For example, if response time is less than 0.1 sec, whatever the user is doing is "interactive" and does not disrupt the flow of the task.
I remember there were similar statistics for web page response time (number of lost views as response time increased). These seem like they might be similar to app launch speed.
That said, I wonder if this "ios spp launch time" post was something that management pursued in a data-driven way, or some engineer getting annoyed and scratching an itch (or something in the middle)
For example, if response time is less than 0.1 sec, whatever the user is doing is "interactive" and does not disrupt the flow of the task.
I remember there were similar statistics for web page response time (number of lost views as response time increased). These seem like they might be similar to app launch speed.
That said, I wonder if this "ios spp launch time" post was something that management pursued in a data-driven way, or some engineer getting annoyed and scratching an itch (or something in the middle)
> I'm curious about what metrics mobile developers use to prioritize tasks.
This is a very MBA take. Task priority should always be considered beforehand, but whenever there is some leeway (including "20% time") I contend that performance tasks should be given some preference. There is almost no end to the ill effects of slow software.
This is a very MBA take. Task priority should always be considered beforehand, but whenever there is some leeway (including "20% time") I contend that performance tasks should be given some preference. There is almost no end to the ill effects of slow software.
Given the performance of most mobile phones, hitting below 400ms to launch and be usable feels like a low bar to cross.
Yeah 600ms to 300ms is noticeable, if you play online games 200ms lag gets killed by 50ms everytime
But that's exactly the poster's point. You don't get headshot in doordash. Slightly slower performance doesn't actually change anything about your use of the app, until it becomes slow enough to make you stop using it (thus, the threshold).
Optimizing startup performance is respecting your user’s time.
“It’s not slow enough to make someone give up” isn’t a performance metric that puts your users first.
“It’s not slow enough to make someone give up” isn’t a performance metric that puts your users first.
This is such a weird thread. The question was essentially about optimization having diminishing returns at some point. Yes, we can spend 10,000 dev hours getting another 50ms off the start time because that's respecting the user's time... but if nobody is going to leave because of that extra time, why not do something else with that labor?
Yes, and specifically because I believe startup time to be a rare occurrence when using an app.
According to a talk I found [here](https://developer.apple.com/videos/play/wwdc2019/423/): there are three types of launches; cold, warm, and hot. Warm is what's typically profiled and occurs when the app has been run at least once but has been closed since, while hot launches are what occur when bringing an app to the foreground. I assume warm launches are what are being profiled.
I don't have any statistics, but my observation is that most people do not exit out of apps and instead just background them, which suggests warm launches are relatively rare if my understanding of which state triggers which type of launch is correct.
According to a talk I found [here](https://developer.apple.com/videos/play/wwdc2019/423/): there are three types of launches; cold, warm, and hot. Warm is what's typically profiled and occurs when the app has been run at least once but has been closed since, while hot launches are what occur when bringing an app to the foreground. I assume warm launches are what are being profiled.
I don't have any statistics, but my observation is that most people do not exit out of apps and instead just background them, which suggests warm launches are relatively rare if my understanding of which state triggers which type of launch is correct.
Slow enough to notice is slow enough to annoy somebody out there. Yes certainly there are diminishing returns, but if you can be noticeably faster than your competitors, that makes a really good impression.
It’s a weird thread and not comparable in any meaningful way. Latency to actions performed multiple times per second to a one shot event is not useful due to it being an entirely different context.
Ok, maybe I misrepresented what a good threshold is. I certainly don't expect developers anywhere to target "minimum viable load time". But the comment I was responding to was totally off the mark, so I was explaining that.
> I certainly don't expect developers anywhere to target "minimum viable load time".
Is this not the job of your performance team?
Is this not the job of your performance team?
You misunderstand. I said target, meaning their goal would be the slowest time they could get away with. That is not an acceptable goal; an app should be faster than that.
Online multiplayer video game latency and app launch latency are very different things and perceived very differently, though.
Depends on what you consider important. Do you want to reduce churn? Optimizing startup performance is one of the best ways you can do that.
Never done any serious development, can someone please educate me whether any of these three issues can and should be targeted earlier in development? For example is any of the first two directly going against some well known best practices? I'm judt curious, not trying to insinuating anything as I don't understand iOS development.
A lot is silly issues can be ignored in any small app, and will become big later on.
If you picked good habits from past scars, stick to them. Otherwise, concentrate on functionality, dogfooding on real devices that real people have as much as possible, and use profiling to find the bottlenecks that emerge when you find the time (since you’re focusing on functionality).
(Exceptions to this rule exist, like if your product is some cloud service then speed might be an actual functional requirement of whatever you’re building)
If you picked good habits from past scars, stick to them. Otherwise, concentrate on functionality, dogfooding on real devices that real people have as much as possible, and use profiling to find the bottlenecks that emerge when you find the time (since you’re focusing on functionality).
(Exceptions to this rule exist, like if your product is some cloud service then speed might be an actual functional requirement of whatever you’re building)
Thanks!
Using Strings in any performance-critical situation, like object identifiers, is a newbie mistake (but also extremely common). That one shouldn't have happened. The others just strike me as things one learns about and fixes as the project matures and someone bothers to do a perf analysis to find the low-hanging fruit.
…this is not very good advice? Using strings is fine, until it becomes a problem. People are going to read your comment and decide to change all their strings to integers or something at the cost of maintainability.
Thanks! Is the reason Strings impact performance because we can use smaller objects to do such work while Strings are larger?
It's not necessarily about the size itself, but more about the fact that it has to go through a memory allocator and it has to be GC'd if that's applicable, while a simple integer doesn't. Copies are more involved too.
Using strings for identifiers is almost always a bad idea.
Using strings for identifiers is almost always a bad idea.
Not something I had considered. So for example a UI component that might load 3 different versions based on a string identifier, should instead use an enum which maps to integers? I say an enum because this would preserve readability of the code.
Do you mean an API entirely internal to your application? In that case, yes, you probably want to use integers (enums), not Strings, to choose what to display.
If you are interfacing with other APIs that use Strings, it may make sense to just pass those through. For example loading files from disk or pulling up UI classes from the OS library using some String identifier or something. It's hard to say without more context.
If you are interfacing with other APIs that use Strings, it may make sense to just pass those through. For example loading files from disk or pulling up UI classes from the OS library using some String identifier or something. It's hard to say without more context.
Yes I was referring to internal APIs. Thanks
This is not true on iOS for most strings.
Why is that?
My guess is they are talking about some optimizations iOS does to make strings more performant, like interned string constants and tagged pointers. The majority of string usage probably falls under those.
Working with dynamically allocated strings, like reading from files, rendering from data bytes, working with C strings or building formatted strings, might have worse performance characteristics.
Working with dynamically allocated strings, like reading from files, rendering from data bytes, working with C strings or building formatted strings, might have worse performance characteristics.
Basically yeah. At a super rough level of understanding, the CPU can compare two integers with one instruction, but has to loop through a whole string[1] one character at a time to compare two strings for equality.
[1] Yeah yeah, CPUs & standard libraries are smarter than that, I know, I know. You get the point.
[1] Yeah yeah, CPUs & standard libraries are smarter than that, I know, I know. You get the point.
Most String comparisons are <5 instructions
No. Functionality first. Optimization later.
You'll want to fix most of the problems relatively late in development, although I can't recommend enough testing on the most low-powered hardware from the get-go. It will let you know immediately when you've written slow code.
It's easier to fix a design mistake just when you've made it than when you've got six months of development hinging on the poor design choice.
It's easier to fix a design mistake just when you've made it than when you've got six months of development hinging on the poor design choice.
Functionality first, but I'd say that you should have a healthy skepticism on third-party libraries - not a "we'll write our own instead" but a "do I really need this feature/tracking".
Actually, writing your own is often underrated.
In many cases the time and code required to incorporate some aspect of a 3rd party lib to do something is similar to the amount of time and code in building what you need. In that case, the dependency only serves to make your code more complex (and slow).
This is not always the case, but surprisingly often.
In many cases the time and code required to incorporate some aspect of a 3rd party lib to do something is similar to the amount of time and code in building what you need. In that case, the dependency only serves to make your code more complex (and slow).
This is not always the case, but surprisingly often.
No this would be over optimization
An astronomical simulator loading dark sky data, grabbing your location, charting the current positions of the stars in relation to your location, displaying detailed graphics for constellations, implementing gyroscopic controls for real-time manipulation of the viewport, and loading all overhead objects into memory: loads nearly instantaneously, responds quickly.
A food delivery app: so bloated and sluggish it is borderline unusable and 100% embarrassing.
A food delivery app: so bloated and sluggish it is borderline unusable and 100% embarrassing.
Now if only they could retain the search parameters when you hit the back button. Currently it takes you to the default list with no filters applied.
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The DoorDash iOS app is so horrendously slow and laggy on my iPhone 14 Pro (as it was on my 11 Pro) that I’m using other delivery services whenever I can. That means if the restaurant I want to order from is available on another platform, I’ll use that.
Great, now make it so tracking my delivery driver doesn't freeze my phone and force me to restart.
If they care so much about the user experience, how come they never came out with an iPad version?
I wonder how exactly did they manage to prevent dynamic loader from initing that framework.
These people are very professional. They must get a salary raise. Their tech is advanced, way above threshold and the service they offer is perfect. Give them a medal.
This would be more impressive if I still used Door Dash.
>At DoorDash, we take app startup speed extremely seriously. We are obsessed with optimizing our customers' experience and making continuous improvements.
I wonder if they actually believe this? They make it almost impossible to report bugs in the app, and when I have customer support's reaction has been "there's not really anything I can do about this."
I wonder if they actually believe this? They make it almost impossible to report bugs in the app, and when I have customer support's reaction has been "there's not really anything I can do about this."
This is because most B2C apps have realized that bug reports are pretty much worthless and cost more time to sift through than any potential upside. Why report bugs when you have crash handlers, telemetry, and detailed logs of everything every user does in the app. Your metric dashboards and reports can actually see and measure issues that actually affect the business.
Not an unfair point, although it is alarming at work how many bugs end up being reported directly from customers.
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I apologize if this comes out as negative, but it truly is an honest question.
They are a tens-of-billions company. Why is this news? Shouldn't this be just part of doing business?
They are a tens-of-billions company. Why is this news? Shouldn't this be just part of doing business?
Because it's a helpful contribution to the the engineering community?
Doordash is a zombie company propped up by VCs, their tech is trash. I remember reading their "ML Engineering blog" and it was the most elementary crap every, they just used google maps apis for delivery and we're trying to do point in polygon calculations. The fact they herald things that are kind of simple and obvious to speaks volumes.
It's their engineering blog... This is what engineering blogs talk about and you are on hacker news where things like this are of interest.
Many people here are iOS developers who would like to see how to improve launch times in their own app.
Recruiting
That’s quite nihilistic.
Why are any of the other posts on HackerNews here? Many are less technical or less interesting, depending where your interests are.
This post at least shows how certain things might be debugged and some performance tweaks that people might forget to make.
The bar for interest is arbitrary. One can choose to not engage and move on if they don’t think it’s interesting.
Why are any of the other posts on HackerNews here? Many are less technical or less interesting, depending where your interests are.
This post at least shows how certain things might be debugged and some performance tweaks that people might forget to make.
The bar for interest is arbitrary. One can choose to not engage and move on if they don’t think it’s interesting.
It's an engineering blog targeting other engineers. Some engineers discovered something that had a significant impact so they are communicating it to more engineers.
It's just PR, and/or some internal stunt by the eng team for better performance reviews. Both of which are fine, if the article itself is actually useful. In this case, I feel like the only thing that could have been interesting is the dyld workaround, but they don't go into depth with that at all. The first two "solutions" feel like they were just doing it inefficiently in the first place, rather than some novel technique worth sharing
Most performance wins are someone doing something inefficiently in the first place. Shocker!