Answering your questions about Heroku routing and web performance

https://blog.heroku.com/archives/2013/4/2/routing_and_web_performance_on_heroku_a_faq

by adamwiggins • 13 years ago

205 154 13 years ago

blog.heroku.com

scottshea3• 13 years ago

So their solution to the random routing is for the customer to switch to Unicorn/Puma on JRuby. Wow.

adamwiggins38• 13 years ago

Yes, because that is the solution. Empirically.

We've run many experiments over the past month to try other approaches to routing, including recreating the exact layout of the Bamboo routing layer (which would never scale to where we are today, but just as a point of reference). None have produced results that are anywhere near as good as using a concurrent backend. (I'd love to publish some of these results so that you don't have to take my word for it.)

That said, we're not done. There are changes to the router behavior that could have an additive effect with apps running Unicorn/Puma/etc, and we'll continue to look into those. But concurrent backends are a solution that is ready and fully-baked today.

habosa2• 13 years ago

Please publish these results. I think a chart showing that Unicorn + Random routing is better than Thin + Intelligent routing would go a long way to ending this whole thing. That's assuming that you can make deploying a Unicorn app as easy as it was with Thin ('git push heroku')

boundlessdreamz• 13 years ago

Unless the dyno signals to the router that it is busy, isn't this just postponing the problem? Per dyno, unicorn can handle more requests but requests will still get queued at dyno level if one of the requests is a slow one (say 2-3 seconds)

tjb• 13 years ago

We also adopted Unicorn pretty early on but still suffered issues as dynos simply ran out of memory. In fact with some apps we have seen improvements (but still far from acceptable) in stability by un-adopting this method. The issues raised by scottshea below, as a consequence concern me, what/will be the charge for these as well?

To be honest it's the fumbling around in the dark that has annoyed me. I am with you 100% on your manifesto and your points about the type of service you provide. However the time we have spent on this (starting before you came clean about the issues) and the time spent on other increasingly suspicious advice to "up dynos" or spend time "optimising your app" sours this slightly. I accept the "magic black box" comes with its compromises and required understanding at our end but it also means needing to be far more communicative and honest about it at yours. Something which you are putting right I can see.

I for one think the premise of Heroku is a great one and you have succeeded for us in many of the things you have set out to achieve. This whole situation has been a real shame, I'm sure this must have a been a pretty shody time for you guys and I hope you come out the better for it. The quicker the better to be honest so you can focus on the new features we'd like to see.

hglaser3• 13 years ago

This is a great response. I'm curious why something like this wasn't posted within 24 hours of RapGenius going public? I'd bet that a more thorough, technical reply would have mitigated a lot of the PR issues.

steveklabnik• 13 years ago

When admitting fault in response to a customer that spends 5 figures/month with you, wise to have a lawyer go over it first.

hglaser3• 13 years ago

I would argue that the brand risk -- e.g. the risk of what ended up happening -- outweighs the legal risk.

That's not to say I wouldn't send it to a lawyer. But I'd do it with some hustle. Something like: "This is going out in 24 hours. Please comment ASAP!"

adamwiggins38• 13 years ago

Agreed, I wish we could have done it much sooner. It took a shocking amount of time to sort through all the entangled issues, emotion, and speculation to try to get to the heart of the matter, which ultimately was about web performance and visibility.

Also, we wanted to respond to our customers first and foremost, and general community discussion second. So we spent close to a month on skype/hangout/phone with hundreds of customers understanding how and at what magnitude this affected their apps.

That was hugely time-consuming, but it gave us the confidence to speak about this in a manner that would be focused on customer needs instead of purely answering community speculation and theoretical discussions.

hglaser3• 13 years ago

Thanks for replying. As a paying Heroku customer (who's not affected by the routing issue), while seeing a blog post earlier would have been nice, it's great to hear that you spent so much time with affected customers.

jfim• 13 years ago

It's pretty much what they have been saying all along; Heroku switched to random routing to support other stacks than only Rails and they kept the routing infrastructure between Cedar and Bamboo the same, resulting in an undocumented performance degradation for large customers still on the old stack or running non-concurrent web frameworks on the new one. The last part was an oversight on Heroku's part, but the rest makes sense, especially considering Cedar supports other stacks than just Rails, including massively concurrent ones(Nodejs, Play, etc.).

The rest of the whole thing was people who were unsatisfied by the change and wanted the old product offering to return and/or felt shortchanged by Heroku. Luckily, Heroku doesn't lock you into their platform like GAE does, for example; it's essentially a bunch of shell scripts to deploy binaries on EC2 workers, a hosted instance of Postgres on EC2, some routing and ops as a service. Anyone who wasn't happy about the change could've contacted Heroku to say "you said we would be sold non-random routing, but you've sold us random routing" or moved their app away to another provider or even their own servers.

Does this suck if you wanted the old service? Sure. Witness the flak that the canning of Google Reader got and it's obvious that discontinuing old services isn't exactly a popular decision. On the other hand, you can self-host (it's massively cheaper than Heroku) or switch to another provider. And if there are no other providers that specialize in Rails hosting, isn't that a business opportunity?

ebbv4• 13 years ago

It seems to me that Heroku is still failing to understand (or at least cop to) the fact that the switch from intelligent to randomized routing was a loss of a major reason people chose Heroku in the first place.

A lot of Heroku's apparent value came from the intelligent routing feature. Everybody knew that it was harder to implement than random routing, that's why they were willing to pay Heroku for it.

Nobody's arguing random routing isn't easier and more stable; of course it is.

The problem is that by switching over to it, Heroku gave up a major selling point of their platform. Are they really blind enough not to know this? I have a hard time believing that.

It seems to me the real way to make people happy is to discount the "base" products which come with random routing and make intelligent routing available as a premium feature. Of course, people who thought they were getting intelligent routing should be credited.

tptacek5• 13 years ago

Is anybody operating at Heroku's scale offering centralized request routing queues? At what price?

ebbv4• 13 years ago

Not that I know of but that's why I'm saying it would be a premium product. Likely pricing would have to scale with the number of dynos running behind the router.

But that's the service people thought they were getting and what they wanted.

If Heroku prices out the intelligent routing and says; "Ok you can have intelligent routing with your current backend stack, but it's going to cost you $25/mo for evert 10 dynos, or you can switch your stack and use randomized routing for free." Then they are empowering their customers to make the choice rather than dictating to them what they should do.

wmf• 13 years ago

Amazon ELB? It does cost significantly more than Heroku AFAIK.

adamwiggins38• 13 years ago

I hear you. Heroku's value proposition is that we abstract away infrastructure tasks and let you focus on your app. Keeping you from needing to deal with load balancers is one part of that. If you're worried about how routing works then you're in some way dealing with load balancing.

However, if someone chose us purely because of a routing algorithm, we probably weren't a great fit for them to begin with. We're not selling algorithms, we're selling abstraction, convenience, elasticity, and productivity.

I do see that part of the reason this topic has been very emotional (for us inside Heroku as well as our customers and the community) is that the Heroku router has historically been seen as a sort of magic black box. This matter required peeking inside that black box, which I think has created a sense of some of that magic being dispelled.

cynicalkane2• 13 years ago

You sound like a politician talking to someone of the opposite party, in that you say "I hear you", but then completely fail to address anyone's concerns. Selling a "magic black box" that guarantees certain properties, changes them, then lies about having changed them presents a liability for users who want to do serious work.

A major selling point of Heroku is that scaling dynos wouldn't be a risk. This guarantee is now gone and it's not coming back soon even if routing behavior is reverted, because users prefer good communication and trust with their providers. The responses of Heroku are blithe non-acknowledgement acknowledgements of this problem.

ebbv4• 13 years ago

I doubt anyone chose Heroku solely because of the routing algorithm, but the sales point of intelligent routing was certainly an appealing one.

Developers don't want to pay for abstraction just for abstraction's sake, they want to pay for abstraction of difficult things. Intelligent routing is one of those difficult things. Random routing is easy, which is of course why it's also more reliable, but also why you're seeing people feeling like they didn't get what they paid for.

I should be clear; this doesn't affect me personally but I am totally sympathetic with the customers who are bent out of shape about this and I still see a divide between your response and why people are upset, and I'm trying to help you bridge that divide.

rhizome• 13 years ago

I'm sure at least one person's job depends on this working out in the direction they've been trying to go, cf. Blaine Cook (who I think got a raw deal).

aphyr2• 13 years ago

"the switch from intelligent to randomized routing"

As I understand it, Heroku (on the Bamboo stack) didn't up and decide "Hey, we're gonna switch from intelligent to random routing." The routers are still (individually) intelligent. It's just that there are more of them now, and they were never designed to distribute their internal queue state across the cluster. The system as a whole behaves more and more like a random router as the number of intelligent bamboo routing nodes increases.

adamwiggins38• 13 years ago

True, although it's more confusing than this. We didn't make an explicit decision for Bamboo, and thus the big problem — docs fell out of date, at a minimum.

For Cedar, we did make an explicit decision. People on the leading edge of web development were running concurrent backends and long-running requests. Our experimental support for Node.js in 2010 was a big driver here, but also people who wanted to use concurrency in Ruby, like Ilya Grigorick's Goliath and Rails becoming threadsafe. These folks complained that the single-request-per-backend algorithm was actually in their way.

This plus horizontal scaling / reliability demands caused us to make an explicit product decision for Cedar.

josh2600• 13 years ago

I don't understand how the system behaves more intelligently when the edge routers increase. The core routers random behavior gets worse with the larger load, and increasing the number of intelligent routers doesn't help to solve that problem in any meaningful way.

Sorry, correct me if I missed something, but I believe that as the overall volume of system transactions increases (thus necessitating more "intelligent" nodes) the volume of random dispersal from the core routers increases as well, which can create situations like what we saw with RapGenius where some requests are 100ms and others are 6500ms (the reason being that random routing is not intelligent and can assign jobs to a node that's completely saturated). Adding more and more intelligent nodes doesn't solve the crux of the issue, which is the random assignment of jobs in the core routers to the "intelligent" routers/nodes.

This whole situation boils down to this: "Intelligent routing is hard, so fuck it" and that's why everyone is pissed off. Heroku could've said "hey Intelligent routing is hard so we're not doing that anymore" but instead they just silently deprecated the service. It's a textbook example of how to be a bad service provider.

jcampbell1• 13 years ago

Random routing will work fine so long as the operating system has the ability to intelligently schedule the work. The problem is that the dynos were setup to handle request sequentially. Unicorn will help mitigate the problem, but the best solution is to not try and serve webpages from hardware that is about as powerful as an old mobile phone. The 2x dynos are a step in the right direction, but I have no idea why they don't offer a real app server like a 16x dyno.

adamwiggins38• 13 years ago

It's probably easy to guess that once we have 2X dynos, 4X dynos (and up) may be on the way. We'll drive this according to demand, so if you need/want dynos of a particular size, drop us a line.

streptomycin4• 13 years ago

He forgot to explain why they won't be refunding customers who were defrauded.

res0nat0r3• 13 years ago

Because they weren't victims of fraud.

dangrossman• 13 years ago

Is promising one service but delivering another not fraud?

Promises from the Heroku website pre-Rap Genius posts:

    "Incoming web traffic is automatically routed to web dynos, with intelligent distribution of load instantly"

    "Intelligent routing: The routing mesh tracks the availability of each dyno and balances load accordingly. Requests are routed to a dyno only once it becomes available. If a dyno is tied up due to a long-running request, the request is routed to another dyno instead of piling up on the unavailable dyno’s backlog."

    "Intelligent routing: The routing mesh tracks the location of all dynos running web processes (web dynos) and routes HTTP traffic to them accordingly."

    "the routing mesh will never serve more than a single request to a dyno at a time"

Actual service provided: requests are routed randomly to dynos regardless of how many requests they are currently handling or their current load.

streptomycin4• 13 years ago

Even if that's true, you're just distracting from the main point. If I buy X from a company and they don't provide it, I expect a refund.

Like if I order a laptop from Dell and, oops, it gets lost in the mail, it's not okay to just say "oh, we changed our shipping company, so that should happen less in the future."

dandelany2• 13 years ago

I think you're right, and defraud is the wrong word, because fraud implies malicious intent. However, that's almost beside the point - many customers paid for the product that was advertised/documented and received something completely different. Whether or not it was intentional, it should be remediated rather than painted over.

Let's completely ignore the random vs. intelligent routing question for the moment and just talk about the New Relic analytics add-on. Heroku customers were paying ~$40 per month PER DYNO for this service. One of the most compelling things about New Relic is that it not only tracks average request time, but also breaks down this data into its components so developers can see which systems are slowing down their requests. Not only did it fail to report the queueing component, it failed to account for it in the total request time, meaning both values were wrong and basically useless.

I don't understand how Heroku can admit that the tools for which their customers paid obscene amounts of money were completely broken for two years straight and yet do nothing about it besides apologize. The fact that most customers did not realize it was broken does not mean it didn't cause real, tangible harm to their businesses.

It's hard to draw an analogy here since it's rare to use a product for so long without noticing it's not what you paid for, but I'll try - imagine you lease a car for two years. You can pay $500/month for the standard model with n tons of CO2 emissions/mile, or $800/month for a hybrid model with n/5 tons of emissions. You opt for the more expensive hybrid, but after driving the car around happily for two years, you pop the hood only to find that the company gave you the standard model. After complaining to the company, they apologize and give you the standard model. Wouldn't you expect them to also retroactively refund you $300/month for every month you paid for a product that you didn't receive? Does the fact that this was a genuine mistake, rather than an attempt to defraud, change your expectation for receiving a refund? It certainly wouldn't for me.

scorpion032• 13 years ago

The same way Apple doesn't refund the buyers of iPhone 4, at the launch of an iPhone 5?

tvladeck• 13 years ago

All of the stuff that Heroku are doing now to mitigate the routing issues for their Bamboo customers are things they should have done when it first became an issue. They are not going above and beyond in any way to make up for the lost time and money their customers.

Again, this is not about

-how advanced Heroku's technology is on an absolute level

-how challenging routing is for their scale

-what competitors offer in this space and for what prices

This is only about the delta between what Heroku sold their customers and what their customers received. They are collapsing the delta now, by being honest about what they are selling (and improving their offering, it seems), but they are doing nothing to address the long time for which the delta was significant for a subset of their customers.

chc2• 13 years ago

Your complaints are all about the past. What are you looking for here? For Heroku to invent a time machine?

ambrice• 13 years ago

How about refunds? Isn't that the normal response when a company screws up in a way that causes the customers to pay more money?

badgar• 13 years ago

> 1k req/min

Also known as <17 requests per second... or a trickle of traffic. Hooray for using bigger numbers and a nonstandard unit to hide inadequacy!

Does Heroku use req/min throughout their service? I can't understand why they would, unless they also can't build the infrastructure to measure on a per-second basis.

> After extensive research and experimentation, we have yet to find either a theoretical model or a practical implementation that beats the simplicity and robustness of random routing to web backends that can support multiple concurrent connections.

Does this CTO think companies like Google and Amazon route their HTTP traffic randomly? No... he knows there are scaleable routing solutions and random routing isn't the best. So he cites "simplicity and robustness." Here, this means "we can't be bothered."

adamwiggins38• 13 years ago

Re: requests. RPM is the metric that New Relic reports, and it's the one most of our customers use when they talk about traffic. I try to speak in whatever terms are most familiar to our customers.

Re: I can't speak to Google and Amazon, and they aren't representative of the size of our customers anyway. We have discussed with many folks who run ops at many companies that are more on par with the size of our mid- and large-sized customers, and single global request queues are exceedingly rare.

The most common setup seems to be clusters of web backends (say, 4 clusters of 40 processes each) that each have their own request queue, but with random load balancing across those clusters. This is a reasonable happy medium between pure random and global request queue, and isn't too different from what you get running (say) 16 processes inside a 2X dyno and 8 web dynos.

meritt• 13 years ago

I too was shocked at that. Also that 6 dynos is apparently the average size to handle that load.

It takes $179/mo (6 dynos) to handle 17 requests/second? That's insane.

adamwiggins38• 13 years ago

Didn't intend to imply that. Number of dynos needed varies extremely widely, with the app's response time and language/framework being used as the main variables.

There are apps on Heroku that serve 30k–50k reqs/min on 10–20 dynos, typically written in something like Scala/Akka or Node.js and serving incredibly short (~30ms) response times with very little variation. But these are unusual.

The more common case of a website, written in non-threadsafe Rails, with median response times of ~200ms but 95th percentile at 3+ seconds, would probably use those same 10 dynos to do only a few thousand requests per minute. Whether or not you use a CDN and page caching also makes a big difference (see Urban Dictionary for an example that does it well).

But it really depends. We were trying to quantify when you should be worried. If you're running a blog that serves 600 rpm / 10 reqs/sec off of two dynos, you don't need to sweat it.

ozgune• 13 years ago

(I was in the bigger engineering team at Amazon that looked into this between between '04-'08.)

After having notable issues with Cisco's hardware load balancers, there was an internal project at Amazon aimed at developing scalable routing solutions.

After years of development effort, it turned out that the "better" solutions didn't work well in production, at least not for our workloads. So we went back to million $ hardware load balancers and random routing.

I don't know if things changed after I left, but I can tell you it wasn't an easy problem. So I completely buy the robustness and simplicity argument these guys are making.

adamwiggins38• 13 years ago

Awesome info, thanks. This has been exactly our experience.

In theory, clever load distribution algorithms (of which one can imagine many variations) are very compelling. Maybe like object databases, or visual programming, or an algorithm that can detect when your program has hit an infinite loop. These are all compelling, but ultimately impractical or impossible in the real world.

senderista• 13 years ago

Nope, DRR is still dead :)

bhauer• 13 years ago

I am surprised they do not moderate the comments on their blog. They have one visible presently that is plain offensive.

cmelbye• 13 years ago

They still fail to understand that using Unicorn doesn't magically fix this issue. Like, at all. It simply means that the dunk gets tied up when n+1 requests (n is number of unicorn workers) get randomly routed to it instead of just 1. It's in no way comparable to a node.js server that handles thousands of concurrent requests asynchronously. They're simply two different designs, and Ruby's traditional design is fundamentally incompatible with Heroku's router.

velominati• 13 years ago

That's not right. In any configuration the goal is to minimize queue time. What is critical to doing this is having a request queue and a pool of concurrent "workers" (to use the generic queueing theory term) in back of it.

Unicorn uses the operating system's TCP connection queue to queue incoming requests that it is not able to immediately server. While n+1 requests can (and will) get routed to a single dyno, this only results in 1 request being queued. It will be queued until the first of the in-process requests is served, which will take ~ the average response time for the app. Given that the other n requests did not get queued (queue time = 0), the average queue time will equal Sum(queue times) / # requests = Average Response Time / n+1.

persei8• 13 years ago

Is it true that you don't fully buffer body of POST request on router? This limitation works against Unicorn design and makes it hardly a "fix": http://rubyforge.org/pipermail/mongrel-unicorn/2013-April/00...

geekylucas• 13 years ago

Heroku only buffers the request headers: https://devcenter.heroku.com/articles/http-routing#request-b...

adamwiggins38• 13 years ago

Plenty of room for improvement here, sure. Some technical discussion in this thread: https://blog.heroku.com/archives/2013/4/3/routing_and_web_pe...

bradleyjg• 13 years ago

Random routing to concurrent servers works fairly well if the kind of long running requests you need to worry about spend a lot of time blocking for some external service (e.g. a database call). Then you can get a lot of benefit on the from cooperative or preemptive multitasking on the server, and so the performance characteristics, from the point of view of a new request, of each server is roughly the same, and so going to a random server is pretty good.

However, if you have long running requests because they make intensive use of server resources (CPU, RAM) then concurrent servers buys you very little. In that case, sending a new request to a server that is chugging along on a difficult problem is significantly different than sending it to one that isn't. That's where knowing the resource state of each server, and routing accordingly is of huge benefit.

While load balancing is a very difficult problem, with some counterintuitive aspects, it is an area of active research, and there are some very clever algorithms out there.

For example, this article (http://research.microsoft.com/pubs/153348/idleq.pdf) from UIUC and Microsoft introduces the Join-Idle-Queue, which is suitable for distributed load balancers, has considerably lower communication overhead than Shortest Queue (AFAICT the original 'intelligent' routing algorithm), and compares its charateristics to both SQ and random routing.

bifrost• 13 years ago

I'd say there's a major flaw here - "the new world of concurrent web backends" - If now was 1995 I might agree with you, but having concurrency in web-app servers is not new. The lack of concurrency in test/demo app situations is totally understandable, in a production environment you'd have to be completely bonkers to think thats ever useful. I also agree that "having to deal with loadbalancing" is something that most people don't get and shouldn't really have to get, but when the way you do loadbalancing is so fundamentally flawed that its worse than Round Robin DNS, you also clearly don't understand it.

To be fair, I have to say I meet people all the time who don't understand it at all and think $randomcrappything is great at loadbalancing. If "connections go to more than one box!" is your metric, then yes, thats loadbalancing. My metric is "Do you send connections to servers that are responsive and not overloaded, maybe with session affinity" and in general most HW loadbalancer products since 1998 have supported that. So if you're not better than 1998 technology, you may want to reevaluate your solution.

bgentry2• 13 years ago

I'd say there's a major flaw here - "the new world of concurrent web backends" - If now was 1995 I might agree with you, but having concurrency in web-app servers is not new.

Sadly, concurrency is relatively new and unfamiliar territory to many in the Ruby on Rails community.

derengel• 13 years ago

Heroku's message: "If you have slow clients you are screwed" Unicorn is designed to only serve fast clients on low-latency.

And no, they don't do any buffering.

adamwiggins38• 13 years ago

I think that overstates it a bit, but yes, there are problems with Unicorn and slow clients. We're investigating: https://blog.heroku.com/archives/2013/4/3/routing_and_web_pe...

If this is an immediate problem for you, it might be worth your while to make your app threadsafe, which gives you more concurrent webserver options.

thatthatis• 13 years ago

What data do you have to show that the random selection algo has superior performance to a round-robin algo?

adamwiggins38• 13 years ago

We investigated round-robin. With N routing (or load balancer) nodes, and any degree of request variance, round robin effectively becomes random very quickly.

deedubaya• 13 years ago

Haters gonna hate.

I wonder how many people bitching here are actual customers who are having problems that haven't been address with a solution. I'm guessing that number is low.

Oh, you're a potential customer? That's why you're bitching? About a problem you may or may not have if you actually choose the product? Think about that argument for a second.

I've never seen such a transparent response and follow up as I have from Heroku on this issue. Most other companies would have gone into immediate damage mitigation mode and let the wound heal instead of re-opening it and giving feedback on how to fix the problem as Heroku has.

I applaud the Heroku team for their effort on their platform and being a kickass company.

stickfigure2• 13 years ago

I'm a real customer with real problems. Grep this page for latchkey's description of it.

The funny thing is, I don't have much sympathy for Rails users. Scaling problems with a single-threaded, serial request-processing architecture? No surprise there. But we have inexplicable H12 problems with Node.js. There's something broken in the system and it isn't random routing.

Cabal• 13 years ago

You're talking like Node offers real concurrency. It doesn't.

latchkey7• 13 years ago

I am working for a fairly large heroku app running Node on ~50-100 web dyno's with another 20-50 backends. Here are the problems as I see it:

We get H12's all the time. Randomly. The only suggestion we get from Heroku is to make the requests process as fast as possible. Thus, we've spent considerable amount of time going through everything we can possibly do to make all requests respond as fast as possible. I've given up. I see this as a fundamental issue with the routing system. If you are going to use Heroku for a large production deployment, H12's (and your users getting dropped connections) will become a fact of life.

There is no auto scaling. We have no idea how many dyno's we actually need. So, we over do it in order to handle peek traffic times. This must be a great money maker for Heroku. There is no incentive for them to build auto scaling into their system because that would mean they wouldn't make as much money. Yes, auto scaling is a hard problem to solve, but there should at least be a plan to start on it and there is none that I have found.

Up until someone bitched loudly, nothing was happening to fix any of this. We have an expensive paid support contract with Heroku and before this whole routing issue blew up in public, their only recommendation was to tune the app more and buy into NewRelic for ~$8k / month. We did both and found NewRelic to not give any relevant information to help us. We did a NodeTime trial for ~$49/mo and that actually helped a lot in identifying slow spots in our app. We fixed all the slow spots in our app and still see an endless stream of H12's. Regardless, it shouldn't take a public bitch slapping for a company to listen to their customers.

You log into a dyno and see a load average of 30+. Who knows if that number is accurate or how big the underlying box really is, but regardless, I can't imagine that number being good. Am I getting H12's because I'm on an overloaded box or is it because the routing system is fundamentally broken? I don't know and nobody can tell me. This is not a good position to be in.

I have heard from several sources that Heroku isn't happy being on AWS and has been wanting to migrate off AWS for a while now. So, if your hosting provider isn't happy on their hosting provider, there must be a reason for that and in the bigger picture, you the customer, is getting screwed.

Given these things, I will never recommend that a company use Heroku. It is great if you know you are going to never have more than one dyno, but if you think you are going to go into a large production system with it, it is far better to find something else. Which brings me to another rant... how come none of these other PaaS solutions are as easy as Heroku? The git deploy is seriously the one thing they got mostly right. I'd love to see someone build a layer on top of all the PaaS solutions so that I can just deploy my code to any one of them (or event multiple).

adamwiggins38• 13 years ago

We're aware of the random H12s problems. Some apps are affected pretty badly, others not at all, and we're not sure why yet. Sorry that you've had such a bad experience with this. We're continuing to investigate. If we're not able to find a solution in a timely fashion, I'll completely understand if you no longer want to use our product for this app.

Knowing how many dynos you need is definitely a problem. We have implemented autoscaling in the past... but it always sucked. It's hard to find a one-size-fits-all-solution. Rather than ship something sub-par we chose not to ship anything at all.

I understand a lot of people do well with autoscaling libraries and 3rd party add-ons. Would be curious to hear your experience with any of these.

I completely agree that it shouldn't take complaining in public to get a company to listen to its customers. That's was our biggest mistake in all of this, IMO — not listening.

For dyno load, have you tried log-runtime-metrics? https://devcenter.heroku.com/articles/log-runtime-metrics It provides per-dyno load averages.

I gladly accept your compliment that our git deploy remains the best on the market. :)

I'm sorry we haven't been able to serve you better. Let me know if you'd be willing to talk via skype sometime — even if you end up leaving the platform (or already have), I'd like to understand in more depth where we went wrong so we can do better in the future.

latchkey7• 13 years ago

Your response only re-enforces my hard won opinion that Heroku should never be used for a production environment for any business that is trying to be successful and popular. Admitting that you have no idea why critical areas of your infrastructure is causing issues, while at the same time charging people an arm and a leg for services (we pay ~$4k/mo) feels like theft to me. I've built solutions for a large porn company that runs on significantly less infrastructure than what we are running on Heroku and handles 100x more traffic. Something is wrong here with the dyno/router model and maybe it is that you guys are just oversubscribed and not admitting to it in public.

Yes, autoscaling is hard. I have apps on Google AppEngine and see their issues as well. That said, at least they are trying. Maybe even take one of those 3rd party libraries and try to harden and adapt that and make it a real solution? I think the real problem though lies in the fact that there isn't any good metrics for what dynos are doing so there is no metric for when something is too busy or not. Yes, log-runtime-metrics puts out some numbers, but those numbers are meaningless when all I have is a slider to change the amount of money we are paying you.

I should qualify that git deploy compliment because there are issues with that as well. For example, why do you have to rebuild the npm modules from scratch each time? Why not have a directory full of pre-built modules for your dyno's that are just copied into my slug? This relatively simple change would increase the speed of deployments greatly. Never mind that deployments aren't reliable and fail randomly. At least it is easy to just try again.

omfg2• 13 years ago

Have you checked out Elastic Beanstalk yet? http://aws.amazon.com/elasticbeanstalk/

Any thoughts on that. It offers a Heroku'esque deploy.

latchkey7• 13 years ago

EBS just recently added support for Node. It's definitely on the list as the next PaaS to try out. AppFog is another one that we've done a JVM deployment to and like a lot except for the fact that it just feels very alpha quality. Their website is painfully slow and under documented and the 'af' command isn't nearly as cool as just doing git deploy remote master.

I should also add that one thing that Heroku did get 100% correct is the heroku logs -t command (aka: tailing the logs). Nobody else does that one quite as well.

dblock• 13 years ago

We have been experimenting with AWS OpsWorks as an option to move forward. It is excellent. Does git.

pytrin• 13 years ago

With that kind of money invested in hosting and scaling, why not get a dedicated professional to handle devops on your team, and go with more traditional hosting solutions? I'm interested in hearing why people still use Heroku at the scale you're describing

latchkey7• 13 years ago

That's a really good question. Heroku is offering to handle the hosting, devops and scaling issues for us so that we can focus our energy on building a killer product. When considering the costs of hiring a devops team and someone to wear a pager 24/7 when servers go down, paying the premium for using Heroku becomes a lot more attractive.

'why not get a dedicated professional to handle devops on your team'

It sure is easy to write that, but the reality isn't as rosy. I've gone through the process at two companies to try to do that, interviewing ~50-80 people and it has been a nightmare. It is really really difficult to find quality devops people. Again, this makes PaaS like AWS, Heroku and AppEngine a lot more attractive. They are betting their entire business on being able to hire good devops people, so they tend to attract better talent.

ROFISH• 13 years ago

Something that's been bugging me about Heroku is that the dyno price has stayed the same ever since launch: $0.05 per hour. Compare to services like Digital Ocean and AWS (who lowered prices significantly in the past few years), Heroku is starting to get very expensive.

The 2X dyno at 2x cost doesn't really make me happy, it just invites me to spend more money when it would be more cost-efficient to move.

cjackson27• 13 years ago

I can't speak to the issues that people are running into when they reach large scale, but I run a small app with two dynos and we've been having issues with H12 request timeout errors for weeks now. This has been bringing down our production app for periods of about fifteen minutes almost daily.

I've been completely disappointed with Heroku's support so far. First they obviously skimmed my support request and provided a canned response that was completely off base. Their next response didn't come for four days and only after I called their sales team to see what I could do to get better support. Their only option is a $1k / mo support contract. If you're running a mission critical app, I'd think twice before choosing Heroku.

adamwiggins38• 13 years ago

The difficulty of diagnosing H12 errors is really challenging. One thing I can recommend is using the http-request-id labs feature: https://devcenter.heroku.com/articles/http-request-id With this enabled and some code in your app, you can correlate your app's request logs directly against the router logs and trace what happened with any particular H12.

I'd be happy to help you do this if you're game. Contact me via adam at heroku dot com.

Could you also email me some links to your support tickets so I can check out what happened there?

jholman2• 13 years ago

I'd like to start by acknowledging that I'm one of the "non-customers who are watching from the sidelines". I think Adam's right that this is an important distinction.

Adam, there's something that confuses me about this. I'm no expert in routing theory, nor have I done the experiments, so forgive me if my reasoning misses something.

I understand why RapGenius took you up on your original promises of "intelligent routing", and I think I understand what you're saying about scaling, and how scaling "intelligent routing" is so far unsolvable, and the motivation for your transition from Bamboo to Cedar, especially in the context of concurrent clients. What I don't understand is this:

It seems to me that if you split into two (or more) tiers, and random-load-balance in the front tier (hit first by the customer), and then at the second tier only send requests to unloaded clients, that you eliminate RapGenius's problem for customers who followed your specific recommendations for good performance on Bamboo (to go single-threaded and trust the router).

Do you have reason to believe that this doesn't one-shot RapGenius's problem? Do you have strategic/architectural reasons for rejecting this even though it would work? Did you try it and it failed? What's the story there?

Maybe I'll write a simulator to (dis)prove my naive theory. :P

adamwiggins38• 13 years ago

> It seems to me that if you split into two (or more) tiers, and random-load-balance in the front tier (hit first by the customer), and then at the second tier only send requests to unloaded clients [...]

I'm unclear how you'd think introducing a second tier changes things. That tier would need to track dyno availability and then you're right back to the same distributed state problem.

Perhaps you mean if the second tier was smaller, or even a single node? In that case, yes, we did try a variation of that. It had some benefits but also some downsides, one being that the extra network hop added latency overhead. We're continuing to explore this and variations of it, but so far we have no evidence that it would provide a major short-term benefit for RG or anyone else.

> Do you have reason to believe that this doesn't one-shot RapGenius's problem?

As a rule of thumb, I find it's best to avoid one-shots (or "specials"). It's appealing in the short term, but in the medium and long term it creates huge technical debt and almost always results in an upset customer. Products made for, and used by, many people have a level of polish and reliability that will never be matched by one-offs.

So if we're going to invest a bunch of energy into trying to solve one (or a handful) of customer's problems, a better investment is to get those customers onto the most recent product, and using all the best practices (e.g. concurrent backend, CDN, asset compilation at build time). That's a more sustainable and long-term solution.

jholman2• 13 years ago

Sorry, yes, I'm supposing that the second tier serves fewer dynos; sufficiently few that your solutions from 2009 (that motivated you to advertise intelligent routing in the first place) are still usable.

> As a rule of thumb, I find it's best to avoid one-shots (or "specials").

Absolutely, and I would never suggest that. However, it's not just RG that has this problem, right? If I understand correctly, isn't it every single customer who believed your advertising and followed your suggested strategy to use single-threaded Rails, and doesn't want to switch?

So it's not about short or medium term; it's about letting customers take the latency hit (as you note), in order to get the scaling properties that they already paid for.

siong1987• 13 years ago

Since we are on the question of visibility of Heroku dyno, what is the amount of CPU power each dyno has?

What about 2Xdyno?

adamwiggins38• 13 years ago

This is a tough area. If you go look at various types of infrastructure providers (e.g. EC2, Linode, Rackspace) you'll see that they always end up making up vague units of measurement (e.g. "cores") and then showing all the resources in reference to whatever the base unit is. So there's really no good way to talk about CPU power like there is with memory.

That said, I can say that a 1X dyno is not very powerful compared to, say, any server you'd purchase for your own datacenter. Our intention is that 2X dynos will provide twice the CPU horsepower, although CPU and I/O are harder to allocate reliability in virtualized environments.

jordanthoms• 13 years ago

My biggest issue with heroku is the general slowness with the API - maybe I'm just impatient, but most simple commands like listing releases, viewing logs etc take at least a second, sometimes five before anything happens. Pushes also take quite a while, even the Git push part is much slower than pushing to github. It's just a general sluggishness which gets annoying after a while.

If they could get all the API requests down under 500ms I'd be much happier.

adamwiggins38• 13 years ago

Yeah, the developer-facing control surfaces on the platform (API calls and git push mainly) have gotten slower over the past year or two. This is on my list of of personal pet peeves, but so far has not made it onto our list of priorities.

We try to drive priorities based on what customers want, not what we want: and what we've heard in the last year or so is all about app uptime, security, and now performance and visibility.

I'm very much hoping that bringing back "fast is a feature" on the developer-facing portions of the product is something we can work on this year.

j-kidd2• 13 years ago

From the article:

> Q. Did the Bamboo router degrade?

> A. Yes. Our older router was built and designed during the early years of Heroku to support the Aspen and later the Bamboo stack. These stacks did not support concurrent backends, and thus the router was designed with a per-app global request queue. This worked as designed originally, but then degraded slowly over the course of the next two years.

From Adam's message on Feb 17th, 2011 (https://groups.google.com/forum/?fromgroups=#!topic/heroku/8...):

> You're correct, the routing mesh does not behave in quite the way described by the docs. We're working on evolving away from the global backlog concept in order to provide better support for different concurrency models, and the docs are no longer accurate. The current behavior is not ideal, but we're on our way to a new model which we'll document fully once it's done.

It looks like random load balancing was already the expected behavior 2 years ago? The "slow degradation" part seems a bit dishonest to me.

adamwiggins38• 13 years ago

There are two separate issues here, and it's easy to get them confused. One is the slow degradation on Bamboo without any change to the routing algorithm code, and the other was the explicit product choice for Cedar with a different code path in the router. Both are described fully here: https://blog.heroku.com/archives/2013/2/16/routing_performan...

The reason it's easy to confuse these two is also part of what confused us at the time. The slow degradation of the Bamboo routing behavior was causing it to gradually become more and more like the explicit choice we had made for our new product.

But of course it's up to you (and everyone else observing) to judge whether this was some kind of malicious intent to mislead, versus that we made a series of oversights that added up to some serious problems for our customers. And that we are now doing everything in our power to be fully transparent about, to rectify, and to make sure never happen again.

j-kidd2• 13 years ago

Sorry about the accusation. I read the Bamboo's issue wrongly. The article from Feb 2013 seems to imply that the slow degradation happened from 2011 to 2013. It starts with "Over the past couple of years", I guess that's what got me confused. The FAQ clarifies that the slow degradation happened from 2009 to 2011.

randall• 13 years ago

I think the most annoying thing is they still don't answer Rap Genius's questions about being owed money for paying megabucks for newrelic. I mean If you offer a service that provides incorrect data for two years and you don't offer any sort of framework for reimbursement, that still seems, at best annoying, at worst, dishonest.

adamwiggins38• 13 years ago

We spent quite a bit of time trying to find a one-size-fits-all framework. There just wasn't one, so we've done credits on a case-by-case basis.

Sorry you find it annoying. It's what was best for our customers.

Answering your questions about Heroku routing and web performance

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