6 ms·

Systems Programming at Twitter

69 points by DanielRibeiro 14y ago

halayli 14y ago
This is more about Scala than systems programming.
- codewright 14y ago
  For that matter, it's an incredibly anachronistic and inaccurate usage of systems programming. People generally reserve systems programming to problems that in order to be solved require something closer to gluing toothpicks than spraying memory.
- rudasn 14y ago
  On topic then, this is the first time I see Scala syntax and was somewhat pleasantly surprised (the only languages I really know are JavaScript and Python). On slide http://monkey.org/~marius/talks/twittersystems/#16 http://monkey.org/~marius/talks/twittersystems/#16: case class Stock(ticker: String, price: Double) { def <(other: Stock) = price < other.price } val goog = Stock("GOOG", 675.15) val aapl = Stock("AAPL", 604.00) aapl < goog == true goog < aapl == false Correct me if I'm wrong but it seems to me that the class Stock gets a method called "<". So appl.< google (or the other way around) would also work. The previous slide also shows this, but the Stock example is makes it even clearer that "Scala is a pure object oriented language: every value is an object." appl and goog are objects, of type Stock, and < is an object, a method of Stock. I wonder if this kind of method would work def ==(other: Stock) = price != other.price and what would happen if it was like this def ==(other: Stock) = self != other (where self would be a reference to the Stock instance, ala python, or this in javascript) and it was invoked like this appl == goog and return true
  - alexdias 14y ago
    Yes, it would work. "==" is a method like any other, and you're overriding it. You should download the Scala IDE and play with a feature called the "Worksheet". See here: https://github.com/scala-ide/scala-worksheet/wiki/Getting-Started https://github.com/scala-ide/scala-worksheet/wiki/Getting-St...
    - rudasn 14y ago
      Cool thanks. Isn't this ability a bit dangerous or worrisome? It means that for every Scala package you use you need to review the code. It does make a good prank though :)
      - Bjartr 14y ago
        It's certainly possible to get out of hand with operator overloading, especially if you try. Take this implementation of "analog literals" in C++ http://www.eelis.net/C++/analogliterals.xhtml http://www.eelis.net/C++/analogliterals.xhtml
      - weego 14y ago
        There is a library called Dispatch that has/had this problem entirely, the author decided to use symbols instead of natural language method names and left it fairly undocumented, so you had to spend time reading the source to have any idea what was going on. To the point where a kindly soul decided to write a periodic table (http://www.flotsam.nl/dispatch-periodic-table.html http://www.flotsam.nl/dispatch-periodic-table.html) to help people with its use. I wouldn't say it was particularly dangerous, but it is a massive pain to deal with (it also means you can google for any help with a particular method).
      - cheald 14y ago
        For what it's worth, this is how Ruby operates, as well - "a + b" is really "a.+(b)". In practice, it doesn't end up being very dangerous. Maybe it's just a community thing (the potential for abuse is certainly there), but it means that you get some really nice, natural-feeling code when you do need to use those overrides.
smegel 14y ago
Yawn. Headline should have been "Scala tutorial".
codewright 14y ago
Do the dispatches from engineering-land from Twitter strike anyone else as: "Please learn Scala, we can't hire people that already know Scala. Please? Learn Scala." The last presentation of any substance I saw re: Twitter Engineering was their cute BitTorrent based deployment stack.
- DanielRibeiro 14y ago
  If you take slides 52[1] to 63[2], you can see the emphasis put into run-time diagnosis. Which is really important for largely distributed systems. Google wrote a little about it when they introduced their global run-time performance tracing tool called Dapper[3] in "Dapper, a Large-Scale Distributed Systems Tracing Infrastructure"[4]" Modern Internet services are often implemented as complex, large-scale distributed systems. These applications are constructed from collections of software modules that may be developed by different teams, perhaps in different programming languages, and could span many thousands of machines across multiple physical facili- ties. Tools that aid in understanding system behavior and reasoning about performance issues are invaluable in such an environment. [1] http://monkey.org/~marius/talks/twittersystems/#52 http://monkey.org/~marius/talks/twittersystems/#52 [2] http://monkey.org/~marius/talks/twittersystems/#63 http://monkey.org/~marius/talks/twittersystems/#63 [3] http://highscalability.com/blog/2010/4/27/paper-dapper-googles-large-scale-distributed-systems-tracing.html http://highscalability.com/blog/2010/4/27/paper-dapper-googl... [4] http://research.google.com/pubs/pub36356.html http://research.google.com/pubs/pub36356.html
  - zxypoo 14y ago
    Twitter open sourced Zipkin, their distributed tracing system based on the Dapper paper: http://twitter.github.com/zipkin/ http://twitter.github.com/zipkin/
abhijat 14y ago
It appears to have an error on slide 23, where the flatMap should return 1, -1 at the beginning rather than 1, -2? I don't know enough Scala to say with certainty but that seems to be an error: Seq(1,2,3,4) flatMap { x => Seq(x, -x) } == Seq(1,-2,2,-2,3,-3,4,-4)
- domlebo70 14y ago
  Yeah you're right.
duncans 14y ago
Off-topic somewhat, but I appreciate the way the slides used `location.replace('#'+n)` so my browser history wasn't littered with slide navigations, hence the back button brought me back here (but slides are still bookmarkable).
tzury 14y ago
Well, aapl < goog == true Should be false, at least by real market values. ;-)
deleted 14y ago
[deleted]
shin_lao 14y ago
Scala is interesting but as others have pointed out, I think it gives a disservice to the presentation to call it "Systems programming at Twitter" . To me it shows two things: * The author doesn't know what system programming is; * Future, promises and generally speaking asynchronous operations are I/O management 101. It doesn't paint your company in a good light to exhibit these techniques as "how we do things". Am I too pedantic?
- frou_dh 14y ago
  Bikeshedding what constitutes Systems Programming has been done to death in Go-related discussions.
- pretoriusB 14y ago
  >The author doesn't know what system programming is No, it's that systems programming is not what it was. The term now also applies to large scale server side systems, not just drivers and lower level work. See also how Go was presented as a "systems language" for these same uses. >Future, promises and generally speaking asynchronous operations are I/O management 101. It doesn't paint your company in a good light to exhibit these techniques as "how we do things". I/O 101? You'd be surprised. Take a look around the industry, and even HN posts, and you'll find out this is far far from the truth.
  - jeremiep 14y ago
    I couldn't agree more, if this is I/O 101 then most network programmers I've met weren't even aware this course existed! Heck, back when I was in CS I had one teacher who was saying "use Java applets for web forms, its more secure since you can't right click to view the source to see the field names in order to forge a request". Somehow most of his students ended up on government contracts..
- mariusaeriksen 14y ago
  Hello from the author. Indeed the vernacular has changed, and “systems programming” refers also to the distributed systems server software. Composable futures and promises are still fairly new in use; I would wager our systems are some of the largest using the techniques described therein. While this talk focused on composable IO and services, there is much more to it. Finagle (https://github.com/twitter/finagle https://github.com/twitter/finagle) is where the rubber meets the road. Its interfaces are described in these terms and it makes great use of their power. Also, as with any talk, it is difficult to convey the message using only the slides.
duaneb 14y ago
Whatever presentation software is used appears to be nigh unusable on the iPad.
- wtracy 14y ago
  I don't know if this helps you, but the presentation is quite readable on a browser that has JavaScript completely disabled.
  - duaneb 14y ago
    Not being a web developer, I really have no idea what the problem is. But it would be fixed with links that connect the slides.
pionar 14y ago
OT, but it took me way too long to figure out how to make the slides advance. I'm an idiot :)
fkaminski 14y ago
I agree this is more about scala than system programming.. I was very happy back then when scala shows up.. but with time i think computer languages should just get out of your way.. be simple as possible.. nowadays im more a Dennis Ritchie/Ken Thompson fan.. they had make simple tools with C and Unix, that just worked.. This is also the Go language school of thought.. Languages must get out of our way, get things done in the simplest way possible.. Functional language people , are more passionate about proving some theoretical points like using immutability all way down.. even if this will blow out your memory resources, or make your code longer.. i think language designers need to be more pratical, and i like when the simplicity way of thought like the one seen in Go comes around the table, to make discussion a little bit more interesting.. We nee more simplicity, work less, so we can be more with our children or family.. and spending less time on our computer.
jebblue 14y ago
I can't get my head around stuff like a function is a value (I can what it's doing, it's the syntax that boggles me) : val f: Int => Int = { x => x*2 } f(123) == 246
- mrcrassic 14y ago
  If you do more functional programming, it will become second-hand to you.
ChrisArchitect 14y ago
err http://news.ycombinator.com/item?id=4732958 http://news.ycombinator.com/item?id=4732958
mattdw 14y ago
When all you have is a flatMap, everything looks like a nested list ;). (The author seems to be shoe-horning a lot of different concepts into flatMap via traits. I count several different Monads in there.)
- sanderjd 14y ago
  It is possible that you're making the same mistake you accuse the author of making. "You have a hammer and are seeing everything as a nail, but I have a screwdriver and all those things are actually screws."

69 points by DanielRibeiro 14y ago

halayli 14y ago

This is more about Scala than systems programming.

codewright 14y ago
For that matter, it's an incredibly anachronistic and inaccurate usage of systems programming. People generally reserve systems programming to problems that in order to be solved require something closer to gluing toothpicks than spraying memory.
rudasn 14y ago
On topic then, this is the first time I see Scala syntax and was somewhat pleasantly surprised (the only languages I really know are JavaScript and Python). On slide http://monkey.org/~marius/talks/twittersystems/#16 http://monkey.org/~marius/talks/twittersystems/#16: case class Stock(ticker: String, price: Double) { def <(other: Stock) = price < other.price } val goog = Stock("GOOG", 675.15) val aapl = Stock("AAPL", 604.00) aapl < goog == true goog < aapl == false Correct me if I'm wrong but it seems to me that the class Stock gets a method called "<". So appl.< google (or the other way around) would also work. The previous slide also shows this, but the Stock example is makes it even clearer that "Scala is a pure object oriented language: every value is an object." appl and goog are objects, of type Stock, and < is an object, a method of Stock. I wonder if this kind of method would work def ==(other: Stock) = price != other.price and what would happen if it was like this def ==(other: Stock) = self != other (where self would be a reference to the Stock instance, ala python, or this in javascript) and it was invoked like this appl == goog and return true
- alexdias 14y ago
  Yes, it would work. "==" is a method like any other, and you're overriding it. You should download the Scala IDE and play with a feature called the "Worksheet". See here: https://github.com/scala-ide/scala-worksheet/wiki/Getting-Started https://github.com/scala-ide/scala-worksheet/wiki/Getting-St...
  - rudasn 14y ago
    Cool thanks. Isn't this ability a bit dangerous or worrisome? It means that for every Scala package you use you need to review the code. It does make a good prank though :)
    - Bjartr 14y ago
      It's certainly possible to get out of hand with operator overloading, especially if you try. Take this implementation of "analog literals" in C++ http://www.eelis.net/C++/analogliterals.xhtml http://www.eelis.net/C++/analogliterals.xhtml
    - weego 14y ago
      There is a library called Dispatch that has/had this problem entirely, the author decided to use symbols instead of natural language method names and left it fairly undocumented, so you had to spend time reading the source to have any idea what was going on. To the point where a kindly soul decided to write a periodic table (http://www.flotsam.nl/dispatch-periodic-table.html http://www.flotsam.nl/dispatch-periodic-table.html) to help people with its use. I wouldn't say it was particularly dangerous, but it is a massive pain to deal with (it also means you can google for any help with a particular method).
    - cheald 14y ago
      For what it's worth, this is how Ruby operates, as well - "a + b" is really "a.+(b)". In practice, it doesn't end up being very dangerous. Maybe it's just a community thing (the potential for abuse is certainly there), but it means that you get some really nice, natural-feeling code when you do need to use those overrides.

smegel 14y ago

Yawn. Headline should have been "Scala tutorial".

codewright 14y ago

Do the dispatches from engineering-land from Twitter strike anyone else as: "Please learn Scala, we can't hire people that already know Scala. Please? Learn Scala." The last presentation of any substance I saw re: Twitter Engineering was their cute BitTorrent based deployment stack.

DanielRibeiro 14y ago
If you take slides 52[1] to 63[2], you can see the emphasis put into run-time diagnosis. Which is really important for largely distributed systems. Google wrote a little about it when they introduced their global run-time performance tracing tool called Dapper[3] in "Dapper, a Large-Scale Distributed Systems Tracing Infrastructure"[4]" Modern Internet services are often implemented as complex, large-scale distributed systems. These applications are constructed from collections of software modules that may be developed by different teams, perhaps in different programming languages, and could span many thousands of machines across multiple physical facili- ties. Tools that aid in understanding system behavior and reasoning about performance issues are invaluable in such an environment. [1] http://monkey.org/~marius/talks/twittersystems/#52 http://monkey.org/~marius/talks/twittersystems/#52 [2] http://monkey.org/~marius/talks/twittersystems/#63 http://monkey.org/~marius/talks/twittersystems/#63 [3] http://highscalability.com/blog/2010/4/27/paper-dapper-googles-large-scale-distributed-systems-tracing.html http://highscalability.com/blog/2010/4/27/paper-dapper-googl... [4] http://research.google.com/pubs/pub36356.html http://research.google.com/pubs/pub36356.html
- zxypoo 14y ago
  Twitter open sourced Zipkin, their distributed tracing system based on the Dapper paper: http://twitter.github.com/zipkin/ http://twitter.github.com/zipkin/

abhijat 14y ago

It appears to have an error on slide 23, where the flatMap should return 1, -1 at the beginning rather than 1, -2? I don't know enough Scala to say with certainty but that seems to be an error: Seq(1,2,3,4) flatMap { x => Seq(x, -x) } == Seq(1,-2,2,-2,3,-3,4,-4)

domlebo70 14y ago
Yeah you're right.

duncans 14y ago

Off-topic somewhat, but I appreciate the way the slides used `location.replace('#'+n)` so my browser history wasn't littered with slide navigations, hence the back button brought me back here (but slides are still bookmarkable).

tzury 14y ago

Well, aapl < goog == true Should be false, at least by real market values. ;-)

deleted 14y ago

[deleted]

shin_lao 14y ago

Scala is interesting but as others have pointed out, I think it gives a disservice to the presentation to call it "Systems programming at Twitter" . To me it shows two things: * The author doesn't know what system programming is; * Future, promises and generally speaking asynchronous operations are I/O management 101. It doesn't paint your company in a good light to exhibit these techniques as "how we do things". Am I too pedantic?

frou_dh 14y ago
Bikeshedding what constitutes Systems Programming has been done to death in Go-related discussions.
pretoriusB 14y ago
>The author doesn't know what system programming is No, it's that systems programming is not what it was. The term now also applies to large scale server side systems, not just drivers and lower level work. See also how Go was presented as a "systems language" for these same uses. >Future, promises and generally speaking asynchronous operations are I/O management 101. It doesn't paint your company in a good light to exhibit these techniques as "how we do things". I/O 101? You'd be surprised. Take a look around the industry, and even HN posts, and you'll find out this is far far from the truth.
- jeremiep 14y ago
  I couldn't agree more, if this is I/O 101 then most network programmers I've met weren't even aware this course existed! Heck, back when I was in CS I had one teacher who was saying "use Java applets for web forms, its more secure since you can't right click to view the source to see the field names in order to forge a request". Somehow most of his students ended up on government contracts..
mariusaeriksen 14y ago
Hello from the author. Indeed the vernacular has changed, and “systems programming” refers also to the distributed systems server software. Composable futures and promises are still fairly new in use; I would wager our systems are some of the largest using the techniques described therein. While this talk focused on composable IO and services, there is much more to it. Finagle (https://github.com/twitter/finagle https://github.com/twitter/finagle) is where the rubber meets the road. Its interfaces are described in these terms and it makes great use of their power. Also, as with any talk, it is difficult to convey the message using only the slides.

duaneb 14y ago

Whatever presentation software is used appears to be nigh unusable on the iPad.

wtracy 14y ago
I don't know if this helps you, but the presentation is quite readable on a browser that has JavaScript completely disabled.
- duaneb 14y ago
  Not being a web developer, I really have no idea what the problem is. But it would be fixed with links that connect the slides.

pionar 14y ago

OT, but it took me way too long to figure out how to make the slides advance. I'm an idiot :)

fkaminski 14y ago

I agree this is more about scala than system programming.. I was very happy back then when scala shows up.. but with time i think computer languages should just get out of your way.. be simple as possible.. nowadays im more a Dennis Ritchie/Ken Thompson fan.. they had make simple tools with C and Unix, that just worked.. This is also the Go language school of thought.. Languages must get out of our way, get things done in the simplest way possible.. Functional language people , are more passionate about proving some theoretical points like using immutability all way down.. even if this will blow out your memory resources, or make your code longer.. i think language designers need to be more pratical, and i like when the simplicity way of thought like the one seen in Go comes around the table, to make discussion a little bit more interesting.. We nee more simplicity, work less, so we can be more with our children or family.. and spending less time on our computer.

jebblue 14y ago

I can't get my head around stuff like a function is a value (I can what it's doing, it's the syntax that boggles me) : val f: Int => Int = { x => x*2 } f(123) == 246

mrcrassic 14y ago
If you do more functional programming, it will become second-hand to you.

ChrisArchitect 14y ago

err http://news.ycombinator.com/item?id=4732958 http://news.ycombinator.com/item?id=4732958

mattdw 14y ago

When all you have is a flatMap, everything looks like a nested list ;). (The author seems to be shoe-horning a lot of different concepts into flatMap via traits. I count several different Monads in there.)

sanderjd 14y ago
It is possible that you're making the same mistake you accuse the author of making. "You have a hammer and are seeing everything as a nail, but I have a screwdriver and all those things are actually screws."