The other day, a friend asked me a seemingly simple question: what's the best way to convert a list of integers into a string, presuming that the integers are ASCII values. For instance, the list [97, 98, 99] should be converted to the string 'abc'. Let's assume we want to write a function to do this.The first version I came up with was totally straightforward: def f1(list): string = "" for item in list: string = string + chr(item) return stringThat can't be the fastest way to do it, said my friend. How about this one: def f2(list): return reduce...

So there's recently been a bit of hype about another Colebourne article: http://blog.joda.org/2011/11/real-life-scala-feedback-from-yammer.htmlI'd like to respond to a few points he makes.First - You should evaluate Scala and pay attention to its benefits and flaws before adopting it.  Yes, there are flaws to Scala.   Working at typesafe makes you more aware of some of them.  We're actively working to reduce/minimize/get rid of these.   In my opinion, the negatives of using Scala are peanuts compared to the postives of choosing Scala over Java.  I think everyone s...

With the releasing of the Lockless Memory Allocator under the GPL version 3.0 license, we can now discuss more of the optimization tricks used inside it. Many of these are things you wouldn't want to use in normal code. However, when speed is the ultimate goal, sometimes we need to break a few rules and use code that is a little sneaky.The SlabA slab is a well-known technique for allocating fixed size objects. For a given object size, a chunk of memory is divided up into smaller regions of that length. Since all the interior objects have the same size, fragmentation is eliminated. The only rea...

Hi! I’m Pavel and I interned at Dropbox over the past summer. One of my biggest projects during this internship was optimizing Python for dynamic page generation on the website. By the end of the summer, I optimized many of dropbox.com’s pages to render 5 times faster. This came with a fair share of challenges though, which I’d like to write about today:The ProblemDropbox is a large website with lots of dynamically generated pages. The more pages that are dynamically generated from user input, the bigger the risk becomes for Cross-site scriptingattacks. To prevent thi...

We've always put a heavy emphasis on performance at Stack Overflow and Stack Exchange. Not just because we're performance wonks (guilty!), but because we think speed is a competitive advantage. There's plenty of experimental data proving that the slower your website loads and displays, the less people will use it.[Google found that] the page with 10 results took 0.4 seconds to generate. The page with 30 results took 0.9 seconds. Half a second delay caused a 20% drop in traffic. Half a second delay killed user satisfaction.In A/B tests, [Amazon] tried delaying the page in increments of 100 mill...