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Ruby on Rails and the importance of being stupid

120 points by lackbeard 17y ago

bittersweet 17y ago
Interesting read. I work with Ruby on Rails myself but I'm not that knowledgeable about scaling it. It seems to me they didn't really know what setup they were running if they are wondering what a 'mongrel' is. I hope they weren't trying to serve the site on only a couple of mongrels. My first thoughts, Benchmark a bit, use a tool like fiveruns to find out what's really happening. I wonder what the real bottleneck is. Of course they shouldn't use a shared database server, but I'm wondering if they are they using caching? What I'm reading about that site I think they could cache the hell out of it. I've only used the builtin Rails cache methods but a tool like memcached should help out on all the database requests.
- jcapote 17y ago
  Thankfully there are numerous parties out there that will handle the scaling issues for you (heroku.com, engineyard.com) so you can concentrate on what's important, the app itself.
  - jmillikin 17y ago
    If the application is performing idiotic operations such as "[querying] MySQL 1500 times with 1500 separate queries (instead of one query returning 1500 rows).", merely moving to a better provider or using more powerful servers won't help. A modern web-based application is very complex -- the programmer has to understand how the database and application communicate, how HTTP works, how to cache data, etc.
    - dallasrpi 17y ago
      This sounds like a simple eager loading fail. Viewing the log for any page hit uncovers these mistakes quickly.
    - pelle 17y ago
      As a RoR developer I have often been hired into optimize various services. One of the biggest issues I have seen is this exponential growth of queries. I have routinely seen requests at clients with 2-3000 queries (even with query caching). Most of them are small, but at that amount it doesn't matter how small and efficient each query is. I love AR to death as an OR library, but it is extremely easy to get into these kinds of issues when you iterate over a large dataset and then call associations of associations without thinking too much about it. I don't think it is only an AR issue, conceptually I think it is true for all ORMs. They can be a PITA to unravel and are often very hard to do in a clean AR like way in more complex data models. Normally you end up doing some fairly un AR like pre loading like you would do in a pre ORM app, which while ugly works.
      - mikeryan 17y ago
        Agreed, I do all my dev with query trace in order to make sure I'm not looping back into individual queries. to those that don't know, Rails doesn't load the children of AR objects by default, so if you do something like Select * from books and then iterate through the books and get books.author_name where the author data is a relational table, you're going to get a separate query for each row.
        ericb 17y ago
        Usually the point where you could get into trouble would look more like: book.author.name in the given example.
  - kingkongrevenge 17y ago
    The article is partly about how hosting service like that sucked.
  - jimboyoungblood 17y ago
    If you're operating a top site/service, scaling is the most important issue you have. It's naive to think that you can get someone else to handle it for you flawlessly.
imownbey 17y ago
"Bad programmer writes bad code" This is hardly a new idea. The fact that a bad programmer used Ruby on Rails, or Django, or PHP, or C++ to write bad code and implement it on a shoddy system is no reflection on anything. This is essentially a story of someone who took good advice for a hosting environment, and someone who took bad advice for a hosting environment. Learn your tool, don't buy into the hype. Make sure you are aware of the reason behind everything that you do (because they I read it on a blog is not a reason). Don't be a bad programmer.
- DougBTX 17y ago
  Simply knowing particular languages has been pointed out on sites not too far away from here as a sign of a Good Programmer. This counts as evidence to the contrary. But not absolute evedence, I guess we all still have to think for ourselves.
  - Periodic 17y ago
    I could understand an argument that knowledge of certain languages is correlated with being a Good Programmer. This guy seems to have heard about the cool tools of the day, jumped in, and failed mostly due to a lack of experience. One great lesson of experience is that there is often a simple solution to complex problems.
jimboyoungblood 17y ago
Yawn. Yet another misinformed "Ruby/Rails can't scale" article. Seems to me the main problem is that his "MIT trained" friend had no experience building a scalable web service. He would've botched it up in PHP, Python, Java, whatever. There's nothing about his main mistakes- running your database on a shared server, naive (ab)use of SQL- that is unique to Rails. And this bit: "pull entire tables into Ruby, the most beautiful computer language ever designed, and filter down to the desired rows using Ruby and its “ActiveRecord” facility" is completely incorrect and makes it obvious Philip Greenspun knows less than nothing about what he's ranting about.
- mattmaroon 17y ago
  I didn't read "Rails can't scale" at all. Did you even finish it? He recommended still using Rails at the end.
  - jimboyoungblood 17y ago
    If this wasn't a RoR hatchet job, why put it in the title and sprinkle sarcastic jabs all over the article? Regarding his recommendation at the end, if someone suggested a server with 32GB of memory to run a site that has "About one user every 10 minutes", I would think "damn, this doesn't scale" :)
    - mattmaroon 17y ago
      It was in the title because many of the snooty programmers who think they're so much smarter than the .NET guys, and who go off and build overly-complicated things that don't work just for the sake of building something complicated, are in love with Ruby on Rails. It doesn't attack RoR so much as a subset of the RoR community. It pretty much abstains from the topic of RoR as a language and framework.
      - donniefitz2 17y ago
        I think you're spot on. And I'm a .Net developer (a bumbling fool no doubt). But really, you grasp the point best so far.
tjogin 17y ago
Shouldn't the lesson to take away from this rather be that it's important to not be stupid? Clearly, the "MIT trained" programmer don't know what what he's doing, at all. I'd expect similarly disastrous results had he used the same 100% ignorant approach to any other language or platform.
luckyland 17y ago
seems to be about ruby and rails by coincidence.
blader 17y ago
Ruby on Rails and the importance of being COMPETENT.
rbranson 17y ago
Umm, it sounds like some tweaking of your ActiveRecord::Base.find calls with the ":include" parameter might improve performance by 10,000x as well.
frodwith 17y ago
Classic case of overengineering the problem. I'd venture that it's a common enough class of mistake for those who have recently learned the hip/new/cool way of doing a thing. Thing = scaling a webservice in this example.
jhawk28 17y ago
ORM is rarely effective unless it is just used for CRUD. Most OOP programmers using ORM rarely use it efficiently.
- mrinterweb 17y ago
  ORMs are extremely useful. Many extensions/plugins/gems/whatever can be developed for an ORM. With ORMs not being tied to one database technology extensions to the ORMs can reach a wide audience. Look at Rail's ActiveRecord. There are many extensions based on that ORM that tie into Rails allowing for developers to not have to recreate the wheel over and over. When using ActiveRecord I have seen how a simple over-site can lead to inefficient database use, but it makes that inefficiency pretty obvious and can usually be easily corrected. ORMs can also take care of query caching and other optimizations for you. If you pay attention to what your ORM is doing for you, an ORM can be efficient and a giant time saver. BTW, what do OOP programmers have to do with things anyway? Do functional or procedural programmers use ORM more efficiently?
lr 17y ago
This is a slam on virtualization, not Ruby/Rails. Bad title, but the overall point remains: When you buy a "slice" of something, you have no idea what you are really buying. If you buy a piece of hardware with 32GB of RAM, then that's what you get. And if you know what you are doing, it is going to be much cheaper than buying "slices." In other words, the whole pizza is always cheaper than if you were to pay for 8 separate slices.
- jmtulloss 17y ago
  Most virtualized infrastructure providers give you some guarantee of how much RAM, CPU, and diskspace you will have available. You may be able to exceed the limits from time to time, but the minimums should be clear when you sign up.
  - Andys 17y ago
    I haven't seen any that guarantee disk access latency.
    - Xichekolas 17y ago
      Probably because it would be impossible without having a dedicated physical disk for each slice on the machine, or some kind of really fancy network storage array. Maybe that will change once SSDs become the default hardware. Without the bottleneck of seek time, latency should be much easier to quantify. Also, since you wouldn't be penalized for "context switching" (I know this term doesn't really apply to disk IO, but I mean switching disk jobs often, which requires a head move on HDs) you could maybe someday slice up the SSD time like a CPU and guarantee it directly. (For instance, if the SSD is capable of 200mbps, you're slice could be guaranteed 10mbps. Or something more technically realistic, I am but an amateur.)
  - lsc 17y ago
    that's not the point; the point is that if you buy 32 1GiB 'slices' even if you are getting completely fair slices that really have 1GiB ram, they are going to cost more than buying one server with 32GiB ram. (now in some situations, 32 1GiB slices are going to be more useful, but 1 32GiB server is going to be cheaper than 32 1GiB slices. ) I sell slices myself; and this is something that should be clear to everyone; the reason why you'd want to buy a slice from me (or someone else) is that a 1GiB slice from me is a lot cheaper than a dedicated server with 1GiB ram. now, some VPS providers have really cool provisioning systems that add a lot of value (I'm still working on mine... but I'm not there.) but those are not unique to virtualization. You can build really cool provisioning systems to work with hardware servers as well. The win from virtualization is that 8 cores/32GiB ram is the most economical server configuration at the moment; with virtualization you can slice that up into smaller servers for people who need less than 32GiB ram /8 cores, and save them a bunch of money.
chaostheory 17y ago
this is a little funny. This isn't the first time Greenspun has been evangelizing the benefits of MS ASP (and now ASP.NET) vs x technology (back then he was deriding Java). The structure of the post is the same: some sensationalism with some missing context (since he doesn't usually do his homework on what he is criticizing). I guess some things don't change (much)
- patrickg-zill 17y ago
  I think he is using the MSFT technology as the worst case or "caveman" approach and then contrasting it with situations where the person outsmarted themselves.
ars 17y ago
"Configure the system with no swap file so that it will use all of its spare RAM as file system cache." That will do EXACTLY the opposite of what he wants. Give it a swap file and unneeded parts of memory will be swapped out to disk, freeing memory for use as a file system cache. There is _never_ a reason to configure a system without a swap file - except if it's a laptop and you don't want the disk to spin up. Don't want the system to use swap space? Don't allocate more memory than you have (or buy more memory), but disabling the swapfile never helps. In some cases disabling it doesn't hurt anything, but it never helps.
- cma 17y ago
  Why should it ever be acceptable for someone to sit down in the morning to a machine with 4GB+ RAM and have things like a volume OSD take tens of painful seconds to swap in because the night before the machine ran 'updatedb' and the system decided to swap out a few bits of "unused program memory" with a useless cache of the entire disk index?
  - jimboyoungblood 17y ago
    Since you know its useless, why not just turn off the updatedb cron job?
    - sokoloff 17y ago
      Because updatedb isn't inherently useless, but rather that file system caching (especially for pages read once) shouldn't eject application pages from RAM to disk. Being able to run locate and have it quickly return an accurate result is useful at times. I just don't want it paging my entire session out to disk every night in order to do that.
      - ars 17y ago
        "I just don't want it paging my entire session out to disk every night in order to do that." It doesn't.
  - 17y ago
dasil003 17y ago
Judging by some of the comments here, it seems people are giving Greenspun a free pass because he's apparently getting at deeper point. However when I read this article, it is chock full of straw men. The comparison between a competent Microsoft programmer vs a complete bumbling fool labeled as an MIT Genius is at best intellectually dishonest. I wrote a lengthy response which I'll post here in case his moderator decides he doesn't like it: I read the moderation policy where it's suggested that reviews of the post are not valued. However I feel an obligation to point out the factual errors in this post. There are dozens of nonsensical assertions and could potentially be very misleading to anyone who doesn't understand Rails or web development in general. My first general critique is that there is no real comparison going on here. It says the business guy called up Microsoft and they recommended buying a bunch of hardware, but there's no discussion of who developed the site or how they got up and running. There's no discussion of the price of the hardware, which clearly looks to be well into the 5-figures, or the price of the fiber connection at home, system administration, backups, etc. To get into some specifics: The programmer, being way smarter than the swaptree idiot, decided to use Ruby on Rails, the latest and greatest Web development tool. As only a fool would use obsolete systems such as SQL Server or Oracle, our brilliant programmer chose MySQL. This is a caricature of an "MIT Genius" that doesn't jive with reality. Anyone who was actually that smart would know better than to dismiss Oracle in favor of MySQL. They may prefer using Ruby on Rails and be more productive than if they used .NET, but they wouldn't go around calling people idiot's for such superficial reasons. Therefore you're not describing an actual genius, just someone who thinks they are a genius, but is actually a fool. Using such a person as the basis for an argument of why Microsoft's recommendations are better than Rails is intellectually dishonest. How do you get scale and reliability? Start by virtualizing everything. The database server should be a virtual “slice” of a physical machine, without direct access to memory or disk, the two resources that dumb old database administrators thought that a database management system needed. The reason that virtualization is done in the web deployment world is so that you can get access to fast and reliable hardware if you need less than the cost of the full resources. A degenerate example would be that if your capacity requirements could be met by a 250mhz processor, you would get better throughput by using 1/8th of a 2Ghz server. The reasoning for this is that the vast majority of sites don't need dedicated hardware, which you seem to imply as being cheaper, but clearly it is not if you are leasing server capacity. Ruby and Rails should run in some virtual “slices” too, restricted maybe to 500 MB or 800 MB of RAM. More users? Add some more slices! I'm going to assume you are talking about EngineYard here, since that is the managed Rails hosting provider I am most familiar with and is somewhat inline with your pricing figures below. First, the 500 or 800 MB is just a base amount of RAM that is good for most small Rails apps. When that starts to run out, the solution is NOT to add more slices, you simply commission more RAM. EY can do this without even restarting your slice. Incidentally you can also commission more CPU if you need it. The reason they start with two production slices is for redundancy. One of your slices goes down for some reason? That's okay because there's a backup. The cost for all of this hosting wizardry at an expert Ruby on Rails shop? $1100 per month. What you described above is a very poor description of what you are paying for at a managed hosting provider like EngineYard. I will describe managed hosting in a minute. But to compare to your unmanaged Microsoft example, I currently pay $8/month for a 256MB of unmanaged hosting that is plenty to server significant traffic on a well optimized app. This is an order of magnitude less than the Verizon FiOS line alone, and provides much better network connectivity (ie. multiple tier-1 connections, lower latency to more endpoints). With managed hosting at EngineYard, you are not just paying for the server. You are basically paying for a fulltime system administrator. They have people all over the world ready to help you at a moment's notice any time of day or night. They proactively monitor your server and contact you if they notice any abnormalities. They provide a large suite of finely tuned recipes and standard software installations that they can install on a moment's notice, and will tie into their monit-based server monitoring setup. The individual machines in the cluster are optimized for their specific tasks. The network hardware and topography is optimized for real world usage scenarios. They continuously tune the machines for throughput and move clients around to avoid bottlenecks. They will even take significant steps towards helping the client tune their own application, above and beyond their contractual obligations for server adminstration. In short, you've completely ignored 95% of what they do, and painted it as extremely expensive without even providing a comparison against the overhead costs of buying and managing your own servers. For the last six months, my friend and his programmer have been trying to figure out why their site is so slow. It could take literally 5 minutes to load a user page. Updates to the database were proceeding at one every several seconds. Was the site heavily loaded? About one user every 10 minutes. If a request on an unloaded server takes 5 minutes to load, and the programmer can not figure it out in 6 months, then that programmer is incompetent plain and simple. Laying this at the feet of Rails is just plain ridiculous. I began emailing the sysadmins of the slices. How big was the MySQL database? How big were the thumbnail images? It turned out that the database was about 2.5 GB and the thumbnails and other stuff on disk worked out to 10 GB. The servers were thrashing constantly and every database request went to disk. I asked “How could this ever have worked?” The database “slice” had only 5 GB of RAM. It was shared with a bunch of other sites, all of which were more popular than mitgenius.com. Are you implying that you need enough RAM to keep the entire database in physical memory? That is patently false. In a worst case scenario, yes it could take performance down quite a bit, but disc access is not nearly as slow as implied above. I've served tons of sites on pure shared hosting (not even virtualized) with much higher load and orders of magnitude better performance than you are describing here. How could a “slice” with 800 MB of RAM run out of memory and start swapping when all it was trying to do was run an HTTP server and a scripting language interpreter? Only a dinosaur would use SQL as a query language. Much better to pull entire tables into Ruby, the most beautiful computer language ever designed, and filter down to the desired rows using Ruby and its “ActiveRecord” facility. This is nonsense Philip. Please don't take this as an ad-hominem, because there's no other way to put this. What you described here is 100% pure nonsense. ActiveRecord, like any ORM component, abstracts away some SQL in order to simplify common database interactions. The lion's share of ActiveRecord code is all about constructing efficient SQL. When you are developing with Rails it shows you all the SQL running the development log, and you can quickly spot n+1 errors. If you need something more efficient, it offers plenty of levels of access right down to pure SQL. In reviewing email traffic, I noticed much discussion of “mongrels” being restarted. I never did figure out what those were for ... What am I missing? To my inexperienced untrained-in-the-ways-of-Ruby mind, it would seem that enough RAM to hold the required data is more important than a “mongrel”. Can it be that simple? I'm shocked that a programmer would speculate so wildly as to say something like this. A mongrel is an application server. I don't understand what you seem to think it is, but it's simply the process serving up Rails requests to the web server and passed through to the client. Typically you run more than one so you can serve multiple requests concurrently, but for a well-optimized app usually no more than 3 or 4 are necessary. Rails uses a non-threaded share-nothing architecture which means you can scale horizontally across unlimited servers. Note that I am not talking about virtualized servers. I'm talking about when you have more traffic than the biggest server in the world can handle, Rails will let you scale out painlessly at the web server level until your database can not be served by a single box. At that point you need to look at database sharding, or alternative data stores using Map-Reduce or some other scalable database solution. None of this is to say Rails doesn't have its warts. Ruby is memory hungry, leaky, and relatively slow. Deployment has traditionally been very complicated compared to something like PHP (although it's much improved with Phusion Passenger aka. mod_rails for Apache/Nginx). There are many reasons why you would be well-advised not to use Rails, however this article doesn't touch on any of them. Rails, just like Oracle, .NET, Java or many other technologies is a proven platform with pros and cons. In this article you pit an apparently competent programmer developing swaptree.com against what can be described as nothing less than a complete bumbling idiot using Rails. You insist the cost of Rails is high without any justification or direct comparison against the costs of swaptree.com. I've read your blog in the past and found it to be pretty interesting, which is why I've taken the time to write this response, and suggest politely that you retract this article.
va_coder 17y ago
This post spoke poorly about two concepts: * query optimization * robust hosting Both of which are generic and have nothing to do with Ruby on Rails in particular.
- deleted 17y ago
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mtarnovan 17y ago
The problem is not that you need better hardware for this scenario, you just need a better programmer. "Not helping matters was the fact that the sysadmins found some public pages that went into MySQL 1500 times with 1500 separate queries (instead of one query returning 1500 rows)." Looks like someone forgot to use :include on some finders. Let's say you have 1000 users with an address each. This will produce 1000 SQL queries: User.all.each do |user| p user.address.street_name end This, however, will only issue two queries: User.all(:include =>:address).each do |user| p user.address.street_name end
- Raphomet 17y ago
  The classic ActiveRecord 1+N trap.
- sunkencity 17y ago
  Well, if you know your way around RoR, the first thing you do after most development is done, is to load the query_reviewer plugin to get an automated profiling on each page, and take steps to limit the number of queries. Either by memcached, or by adding indexes. It's not unusual to go from a couple of hundred queries per page to less than 10 per page in a day of optimizing.
jdavid 17y ago
just built a service in PHP that can process 15,000 rows of data, with a complexity of about O(1000*(10|100)n) and it runs in 4.5min. I was looking to beat 15m. I expect to get that down further. right now i use a LIMIT of 100 to minimize sql queries, and memory. i might try going to 1000 rows or about 10k in data, but in my experience when the DB has to return that much data you are not really gaining that much. what do you think? any other optimizations i should look to?
- cschneid 17y ago
  One optimization is to write big O notation in minimized form. It looks more impressive to write O(n). And to try being helpful: do aggregation in the db where possible, be sure indexes are good, play around with the number of rows you process at a time, use joins if appropriate to minimize queries, if your queries are expensive at all use EXPLAIN, depending on the database, look into using a cursor (maybe?).
  - jdavid 17y ago
    Cursor? I was using LIMIT and OFFSET, did you mean something else? update: I processes 200k-300k rows in a few hours, and since the DB is on the same box, as the php app, there is no need to make this more complicated.
- mrtron 17y ago
  Do all your work in the database...you should be able to crush that speed.
lsc 17y ago
Ram is King for most workloads; and he's right, it's ridiculously cheap. If you need more than 16GiB ram, it makes a lot of sense to buy your own hardware and co-locate it. Now, I disagree about keeping it in your basement, at least once you have users on it. co-locating a 2 cpu box is going to cost you around $100/month, and you get much better connectivity than DSL at that price. DSL isn't much cheaper, if you get a reasonable uplink speed (at least around here) and I don't know about you, but the power in my house (I live in California) isn't exactly /enterprise grade/. But yeah, I see a largely untapped market for renting high-ram otherwise-cheap servers; I've rented out one 32GiB server with a bunch of drives (and some slow CPUs) to a guy for $1200 setup and $175/month... once my next load of servers is up and built, I'm thinking about chasing that business model again, if I can build the servers faster than I get new vps signups, anyhow.
joshu 17y ago
Troll bridge. Pay troll.
- jimboyoungblood 17y ago
  Trolls are usually anonymous.
c00p3r 17y ago
Choice appropriate tools for your task, not the task for available tools. MS fans, Delphi fans, Java fans and now RoR fans are thinking second way - they love their tools. The altrernative approach is about using mix of technologies and tools to complete actual tasks. Today's linux distributions, which are actually mix (if not mess) of applications and tools written on every possible scripting language is a good example. In the area of web-development the same approach works the same way - you can build different [sub]services and [sub]systems with different tools which are more appropriate for some particular task. REST-JSON-Key-Value-Storage here, classic SQL back-end there and so on.
andybak 17y ago
I'd been puzzling why the name was so familiar and it's because this man is the source of the ultimate Smug Lisp Weenie quote... Greenspun's Tenth Rule of Programming: "Any sufficiently complicated C or Fortran program contains an ad-hoc, informally-specified bug-ridden slow implementation of half of Common Lisp."
rue 17y ago
Hm. It seems the linked article is somewhat over-engineered for general consumption.

120 points by lackbeard 17y ago

Interesting read. I work with Ruby on Rails myself but I'm not that knowledgeable about scaling it. It seems to me they didn't really know what setup they were running if they are wondering what a 'mongrel' is. I hope they weren't trying to serve the site on only a couple of mongrels. My first thoughts, Benchmark a bit, use a tool like fiveruns to find out what's really happening. I wonder what the real bottleneck is. Of course they shouldn't use a shared database server, but I'm wondering if they are they using caching? What I'm reading about that site I think they could cache the hell out of it. I've only used the builtin Rails cache methods but a tool like memcached should help out on all the database requests.

jcapote 17y ago
Thankfully there are numerous parties out there that will handle the scaling issues for you (heroku.com, engineyard.com) so you can concentrate on what's important, the app itself.
- jmillikin 17y ago
  If the application is performing idiotic operations such as "[querying] MySQL 1500 times with 1500 separate queries (instead of one query returning 1500 rows).", merely moving to a better provider or using more powerful servers won't help. A modern web-based application is very complex -- the programmer has to understand how the database and application communicate, how HTTP works, how to cache data, etc.
  - dallasrpi 17y ago
    This sounds like a simple eager loading fail. Viewing the log for any page hit uncovers these mistakes quickly.
  - pelle 17y ago
    As a RoR developer I have often been hired into optimize various services. One of the biggest issues I have seen is this exponential growth of queries. I have routinely seen requests at clients with 2-3000 queries (even with query caching). Most of them are small, but at that amount it doesn't matter how small and efficient each query is. I love AR to death as an OR library, but it is extremely easy to get into these kinds of issues when you iterate over a large dataset and then call associations of associations without thinking too much about it. I don't think it is only an AR issue, conceptually I think it is true for all ORMs. They can be a PITA to unravel and are often very hard to do in a clean AR like way in more complex data models. Normally you end up doing some fairly un AR like pre loading like you would do in a pre ORM app, which while ugly works.
    - mikeryan 17y ago
      Agreed, I do all my dev with query trace in order to make sure I'm not looping back into individual queries. to those that don't know, Rails doesn't load the children of AR objects by default, so if you do something like Select * from books and then iterate through the books and get books.author_name where the author data is a relational table, you're going to get a separate query for each row.
      - ericb 17y ago
        Usually the point where you could get into trouble would look more like: book.author.name in the given example.
- kingkongrevenge 17y ago
  The article is partly about how hosting service like that sucked.
- jimboyoungblood 17y ago
  If you're operating a top site/service, scaling is the most important issue you have. It's naive to think that you can get someone else to handle it for you flawlessly.

imownbey 17y ago

"Bad programmer writes bad code" This is hardly a new idea. The fact that a bad programmer used Ruby on Rails, or Django, or PHP, or C++ to write bad code and implement it on a shoddy system is no reflection on anything. This is essentially a story of someone who took good advice for a hosting environment, and someone who took bad advice for a hosting environment. Learn your tool, don't buy into the hype. Make sure you are aware of the reason behind everything that you do (because they I read it on a blog is not a reason). Don't be a bad programmer.

DougBTX 17y ago
Simply knowing particular languages has been pointed out on sites not too far away from here as a sign of a Good Programmer. This counts as evidence to the contrary. But not absolute evedence, I guess we all still have to think for ourselves.
- Periodic 17y ago
  I could understand an argument that knowledge of certain languages is correlated with being a Good Programmer. This guy seems to have heard about the cool tools of the day, jumped in, and failed mostly due to a lack of experience. One great lesson of experience is that there is often a simple solution to complex problems.

jimboyoungblood 17y ago

Yawn. Yet another misinformed "Ruby/Rails can't scale" article. Seems to me the main problem is that his "MIT trained" friend had no experience building a scalable web service. He would've botched it up in PHP, Python, Java, whatever. There's nothing about his main mistakes- running your database on a shared server, naive (ab)use of SQL- that is unique to Rails. And this bit: "pull entire tables into Ruby, the most beautiful computer language ever designed, and filter down to the desired rows using Ruby and its “ActiveRecord” facility" is completely incorrect and makes it obvious Philip Greenspun knows less than nothing about what he's ranting about.

mattmaroon 17y ago
I didn't read "Rails can't scale" at all. Did you even finish it? He recommended still using Rails at the end.
- jimboyoungblood 17y ago
  If this wasn't a RoR hatchet job, why put it in the title and sprinkle sarcastic jabs all over the article? Regarding his recommendation at the end, if someone suggested a server with 32GB of memory to run a site that has "About one user every 10 minutes", I would think "damn, this doesn't scale" :)
  - mattmaroon 17y ago
    It was in the title because many of the snooty programmers who think they're so much smarter than the .NET guys, and who go off and build overly-complicated things that don't work just for the sake of building something complicated, are in love with Ruby on Rails. It doesn't attack RoR so much as a subset of the RoR community. It pretty much abstains from the topic of RoR as a language and framework.
    - donniefitz2 17y ago
      I think you're spot on. And I'm a .Net developer (a bumbling fool no doubt). But really, you grasp the point best so far.

tjogin 17y ago

Shouldn't the lesson to take away from this rather be that it's important to not be stupid? Clearly, the "MIT trained" programmer don't know what what he's doing, at all. I'd expect similarly disastrous results had he used the same 100% ignorant approach to any other language or platform.

luckyland 17y ago

seems to be about ruby and rails by coincidence.

blader 17y ago

Ruby on Rails and the importance of being COMPETENT.

rbranson 17y ago

Umm, it sounds like some tweaking of your ActiveRecord::Base.find calls with the ":include" parameter might improve performance by 10,000x as well.

frodwith 17y ago

Classic case of overengineering the problem. I'd venture that it's a common enough class of mistake for those who have recently learned the hip/new/cool way of doing a thing. Thing = scaling a webservice in this example.

jhawk28 17y ago

ORM is rarely effective unless it is just used for CRUD. Most OOP programmers using ORM rarely use it efficiently.

mrinterweb 17y ago
ORMs are extremely useful. Many extensions/plugins/gems/whatever can be developed for an ORM. With ORMs not being tied to one database technology extensions to the ORMs can reach a wide audience. Look at Rail's ActiveRecord. There are many extensions based on that ORM that tie into Rails allowing for developers to not have to recreate the wheel over and over. When using ActiveRecord I have seen how a simple over-site can lead to inefficient database use, but it makes that inefficiency pretty obvious and can usually be easily corrected. ORMs can also take care of query caching and other optimizations for you. If you pay attention to what your ORM is doing for you, an ORM can be efficient and a giant time saver. BTW, what do OOP programmers have to do with things anyway? Do functional or procedural programmers use ORM more efficiently?

lr 17y ago

This is a slam on virtualization, not Ruby/Rails. Bad title, but the overall point remains: When you buy a "slice" of something, you have no idea what you are really buying. If you buy a piece of hardware with 32GB of RAM, then that's what you get. And if you know what you are doing, it is going to be much cheaper than buying "slices." In other words, the whole pizza is always cheaper than if you were to pay for 8 separate slices.

jmtulloss 17y ago
Most virtualized infrastructure providers give you some guarantee of how much RAM, CPU, and diskspace you will have available. You may be able to exceed the limits from time to time, but the minimums should be clear when you sign up.
- Andys 17y ago
  I haven't seen any that guarantee disk access latency.
  - Xichekolas 17y ago
    Probably because it would be impossible without having a dedicated physical disk for each slice on the machine, or some kind of really fancy network storage array. Maybe that will change once SSDs become the default hardware. Without the bottleneck of seek time, latency should be much easier to quantify. Also, since you wouldn't be penalized for "context switching" (I know this term doesn't really apply to disk IO, but I mean switching disk jobs often, which requires a head move on HDs) you could maybe someday slice up the SSD time like a CPU and guarantee it directly. (For instance, if the SSD is capable of 200mbps, you're slice could be guaranteed 10mbps. Or something more technically realistic, I am but an amateur.)
- lsc 17y ago
  that's not the point; the point is that if you buy 32 1GiB 'slices' even if you are getting completely fair slices that really have 1GiB ram, they are going to cost more than buying one server with 32GiB ram. (now in some situations, 32 1GiB slices are going to be more useful, but 1 32GiB server is going to be cheaper than 32 1GiB slices. ) I sell slices myself; and this is something that should be clear to everyone; the reason why you'd want to buy a slice from me (or someone else) is that a 1GiB slice from me is a lot cheaper than a dedicated server with 1GiB ram. now, some VPS providers have really cool provisioning systems that add a lot of value (I'm still working on mine... but I'm not there.) but those are not unique to virtualization. You can build really cool provisioning systems to work with hardware servers as well. The win from virtualization is that 8 cores/32GiB ram is the most economical server configuration at the moment; with virtualization you can slice that up into smaller servers for people who need less than 32GiB ram /8 cores, and save them a bunch of money.

chaostheory 17y ago

this is a little funny. This isn't the first time Greenspun has been evangelizing the benefits of MS ASP (and now ASP.NET) vs x technology (back then he was deriding Java). The structure of the post is the same: some sensationalism with some missing context (since he doesn't usually do his homework on what he is criticizing). I guess some things don't change (much)

patrickg-zill 17y ago
I think he is using the MSFT technology as the worst case or "caveman" approach and then contrasting it with situations where the person outsmarted themselves.

ars 17y ago

"Configure the system with no swap file so that it will use all of its spare RAM as file system cache." That will do EXACTLY the opposite of what he wants. Give it a swap file and unneeded parts of memory will be swapped out to disk, freeing memory for use as a file system cache. There is _never_ a reason to configure a system without a swap file - except if it's a laptop and you don't want the disk to spin up. Don't want the system to use swap space? Don't allocate more memory than you have (or buy more memory), but disabling the swapfile never helps. In some cases disabling it doesn't hurt anything, but it never helps.

cma 17y ago
Why should it ever be acceptable for someone to sit down in the morning to a machine with 4GB+ RAM and have things like a volume OSD take tens of painful seconds to swap in because the night before the machine ran 'updatedb' and the system decided to swap out a few bits of "unused program memory" with a useless cache of the entire disk index?
- jimboyoungblood 17y ago
  Since you know its useless, why not just turn off the updatedb cron job?
  - sokoloff 17y ago
    Because updatedb isn't inherently useless, but rather that file system caching (especially for pages read once) shouldn't eject application pages from RAM to disk. Being able to run locate and have it quickly return an accurate result is useful at times. I just don't want it paging my entire session out to disk every night in order to do that.
    - ars 17y ago
      "I just don't want it paging my entire session out to disk every night in order to do that." It doesn't.
- 17y ago

dasil003 17y ago

Judging by some of the comments here, it seems people are giving Greenspun a free pass because he's apparently getting at deeper point. However when I read this article, it is chock full of straw men. The comparison between a competent Microsoft programmer vs a complete bumbling fool labeled as an MIT Genius is at best intellectually dishonest. I wrote a lengthy response which I'll post here in case his moderator decides he doesn't like it: I read the moderation policy where it's suggested that reviews of the post are not valued. However I feel an obligation to point out the factual errors in this post. There are dozens of nonsensical assertions and could potentially be very misleading to anyone who doesn't understand Rails or web development in general. My first general critique is that there is no real comparison going on here. It says the business guy called up Microsoft and they recommended buying a bunch of hardware, but there's no discussion of who developed the site or how they got up and running. There's no discussion of the price of the hardware, which clearly looks to be well into the 5-figures, or the price of the fiber connection at home, system administration, backups, etc. To get into some specifics: The programmer, being way smarter than the swaptree idiot, decided to use Ruby on Rails, the latest and greatest Web development tool. As only a fool would use obsolete systems such as SQL Server or Oracle, our brilliant programmer chose MySQL. This is a caricature of an "MIT Genius" that doesn't jive with reality. Anyone who was actually that smart would know better than to dismiss Oracle in favor of MySQL. They may prefer using Ruby on Rails and be more productive than if they used .NET, but they wouldn't go around calling people idiot's for such superficial reasons. Therefore you're not describing an actual genius, just someone who thinks they are a genius, but is actually a fool. Using such a person as the basis for an argument of why Microsoft's recommendations are better than Rails is intellectually dishonest. How do you get scale and reliability? Start by virtualizing everything. The database server should be a virtual “slice” of a physical machine, without direct access to memory or disk, the two resources that dumb old database administrators thought that a database management system needed. The reason that virtualization is done in the web deployment world is so that you can get access to fast and reliable hardware if you need less than the cost of the full resources. A degenerate example would be that if your capacity requirements could be met by a 250mhz processor, you would get better throughput by using 1/8th of a 2Ghz server. The reasoning for this is that the vast majority of sites don't need dedicated hardware, which you seem to imply as being cheaper, but clearly it is not if you are leasing server capacity. Ruby and Rails should run in some virtual “slices” too, restricted maybe to 500 MB or 800 MB of RAM. More users? Add some more slices! I'm going to assume you are talking about EngineYard here, since that is the managed Rails hosting provider I am most familiar with and is somewhat inline with your pricing figures below. First, the 500 or 800 MB is just a base amount of RAM that is good for most small Rails apps. When that starts to run out, the solution is NOT to add more slices, you simply commission more RAM. EY can do this without even restarting your slice. Incidentally you can also commission more CPU if you need it. The reason they start with two production slices is for redundancy. One of your slices goes down for some reason? That's okay because there's a backup. The cost for all of this hosting wizardry at an expert Ruby on Rails shop? $1100 per month. What you described above is a very poor description of what you are paying for at a managed hosting provider like EngineYard. I will describe managed hosting in a minute. But to compare to your unmanaged Microsoft example, I currently pay $8/month for a 256MB of unmanaged hosting that is plenty to server significant traffic on a well optimized app. This is an order of magnitude less than the Verizon FiOS line alone, and provides much better network connectivity (ie. multiple tier-1 connections, lower latency to more endpoints). With managed hosting at EngineYard, you are not just paying for the server. You are basically paying for a fulltime system administrator. They have people all over the world ready to help you at a moment's notice any time of day or night. They proactively monitor your server and contact you if they notice any abnormalities. They provide a large suite of finely tuned recipes and standard software installations that they can install on a moment's notice, and will tie into their monit-based server monitoring setup. The individual machines in the cluster are optimized for their specific tasks. The network hardware and topography is optimized for real world usage scenarios. They continuously tune the machines for throughput and move clients around to avoid bottlenecks. They will even take significant steps towards helping the client tune their own application, above and beyond their contractual obligations for server adminstration. In short, you've completely ignored 95% of what they do, and painted it as extremely expensive without even providing a comparison against the overhead costs of buying and managing your own servers. For the last six months, my friend and his programmer have been trying to figure out why their site is so slow. It could take literally 5 minutes to load a user page. Updates to the database were proceeding at one every several seconds. Was the site heavily loaded? About one user every 10 minutes. If a request on an unloaded server takes 5 minutes to load, and the programmer can not figure it out in 6 months, then that programmer is incompetent plain and simple. Laying this at the feet of Rails is just plain ridiculous. I began emailing the sysadmins of the slices. How big was the MySQL database? How big were the thumbnail images? It turned out that the database was about 2.5 GB and the thumbnails and other stuff on disk worked out to 10 GB. The servers were thrashing constantly and every database request went to disk. I asked “How could this ever have worked?” The database “slice” had only 5 GB of RAM. It was shared with a bunch of other sites, all of which were more popular than mitgenius.com. Are you implying that you need enough RAM to keep the entire database in physical memory? That is patently false. In a worst case scenario, yes it could take performance down quite a bit, but disc access is not nearly as slow as implied above. I've served tons of sites on pure shared hosting (not even virtualized) with much higher load and orders of magnitude better performance than you are describing here. How could a “slice” with 800 MB of RAM run out of memory and start swapping when all it was trying to do was run an HTTP server and a scripting language interpreter? Only a dinosaur would use SQL as a query language. Much better to pull entire tables into Ruby, the most beautiful computer language ever designed, and filter down to the desired rows using Ruby and its “ActiveRecord” facility. This is nonsense Philip. Please don't take this as an ad-hominem, because there's no other way to put this. What you described here is 100% pure nonsense. ActiveRecord, like any ORM component, abstracts away some SQL in order to simplify common database interactions. The lion's share of ActiveRecord code is all about constructing efficient SQL. When you are developing with Rails it shows you all the SQL running the development log, and you can quickly spot n+1 errors. If you need something more efficient, it offers plenty of levels of access right down to pure SQL. In reviewing email traffic, I noticed much discussion of “mongrels” being restarted. I never did figure out what those were for ... What am I missing? To my inexperienced untrained-in-the-ways-of-Ruby mind, it would seem that enough RAM to hold the required data is more important than a “mongrel”. Can it be that simple? I'm shocked that a programmer would speculate so wildly as to say something like this. A mongrel is an application server. I don't understand what you seem to think it is, but it's simply the process serving up Rails requests to the web server and passed through to the client. Typically you run more than one so you can serve multiple requests concurrently, but for a well-optimized app usually no more than 3 or 4 are necessary. Rails uses a non-threaded share-nothing architecture which means you can scale horizontally across unlimited servers. Note that I am not talking about virtualized servers. I'm talking about when you have more traffic than the biggest server in the world can handle, Rails will let you scale out painlessly at the web server level until your database can not be served by a single box. At that point you need to look at database sharding, or alternative data stores using Map-Reduce or some other scalable database solution. None of this is to say Rails doesn't have its warts. Ruby is memory hungry, leaky, and relatively slow. Deployment has traditionally been very complicated compared to something like PHP (although it's much improved with Phusion Passenger aka. mod_rails for Apache/Nginx). There are many reasons why you would be well-advised not to use Rails, however this article doesn't touch on any of them. Rails, just like Oracle, .NET, Java or many other technologies is a proven platform with pros and cons. In this article you pit an apparently competent programmer developing swaptree.com against what can be described as nothing less than a complete bumbling idiot using Rails. You insist the cost of Rails is high without any justification or direct comparison against the costs of swaptree.com. I've read your blog in the past and found it to be pretty interesting, which is why I've taken the time to write this response, and suggest politely that you retract this article.

va_coder 17y ago

This post spoke poorly about two concepts: * query optimization * robust hosting Both of which are generic and have nothing to do with Ruby on Rails in particular.

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mtarnovan 17y ago

The problem is not that you need better hardware for this scenario, you just need a better programmer. "Not helping matters was the fact that the sysadmins found some public pages that went into MySQL 1500 times with 1500 separate queries (instead of one query returning 1500 rows)." Looks like someone forgot to use :include on some finders. Let's say you have 1000 users with an address each. This will produce 1000 SQL queries: User.all.each do |user| p user.address.street_name end This, however, will only issue two queries: User.all(:include =>:address).each do |user| p user.address.street_name end

Raphomet 17y ago
The classic ActiveRecord 1+N trap.
sunkencity 17y ago
Well, if you know your way around RoR, the first thing you do after most development is done, is to load the query_reviewer plugin to get an automated profiling on each page, and take steps to limit the number of queries. Either by memcached, or by adding indexes. It's not unusual to go from a couple of hundred queries per page to less than 10 per page in a day of optimizing.

jdavid 17y ago

just built a service in PHP that can process 15,000 rows of data, with a complexity of about O(1000*(10|100)n) and it runs in 4.5min. I was looking to beat 15m. I expect to get that down further. right now i use a LIMIT of 100 to minimize sql queries, and memory. i might try going to 1000 rows or about 10k in data, but in my experience when the DB has to return that much data you are not really gaining that much. what do you think? any other optimizations i should look to?

cschneid 17y ago
One optimization is to write big O notation in minimized form. It looks more impressive to write O(n). And to try being helpful: do aggregation in the db where possible, be sure indexes are good, play around with the number of rows you process at a time, use joins if appropriate to minimize queries, if your queries are expensive at all use EXPLAIN, depending on the database, look into using a cursor (maybe?).
- jdavid 17y ago
  Cursor? I was using LIMIT and OFFSET, did you mean something else? update: I processes 200k-300k rows in a few hours, and since the DB is on the same box, as the php app, there is no need to make this more complicated.
mrtron 17y ago
Do all your work in the database...you should be able to crush that speed.

lsc 17y ago

Ram is King for most workloads; and he's right, it's ridiculously cheap. If you need more than 16GiB ram, it makes a lot of sense to buy your own hardware and co-locate it. Now, I disagree about keeping it in your basement, at least once you have users on it. co-locating a 2 cpu box is going to cost you around $100/month, and you get much better connectivity than DSL at that price. DSL isn't much cheaper, if you get a reasonable uplink speed (at least around here) and I don't know about you, but the power in my house (I live in California) isn't exactly /enterprise grade/. But yeah, I see a largely untapped market for renting high-ram otherwise-cheap servers; I've rented out one 32GiB server with a bunch of drives (and some slow CPUs) to a guy for $1200 setup and $175/month... once my next load of servers is up and built, I'm thinking about chasing that business model again, if I can build the servers faster than I get new vps signups, anyhow.

joshu 17y ago

Troll bridge. Pay troll.

jimboyoungblood 17y ago
Trolls are usually anonymous.

c00p3r 17y ago

Choice appropriate tools for your task, not the task for available tools. MS fans, Delphi fans, Java fans and now RoR fans are thinking second way - they love their tools. The altrernative approach is about using mix of technologies and tools to complete actual tasks. Today's linux distributions, which are actually mix (if not mess) of applications and tools written on every possible scripting language is a good example. In the area of web-development the same approach works the same way - you can build different [sub]services and [sub]systems with different tools which are more appropriate for some particular task. REST-JSON-Key-Value-Storage here, classic SQL back-end there and so on.

andybak 17y ago

I'd been puzzling why the name was so familiar and it's because this man is the source of the ultimate Smug Lisp Weenie quote... Greenspun's Tenth Rule of Programming: "Any sufficiently complicated C or Fortran program contains an ad-hoc, informally-specified bug-ridden slow implementation of half of Common Lisp."

rue 17y ago

Hm. It seems the linked article is somewhat over-engineered for general consumption.