It depends on what you are intending to do with it. Sets are significantly faster when it comes to determining if an object is present in the set (as in x in s), but its elements are not ordered so you cannot access items by index as you would in a list. Sets are also … Read more
The explanation comes from Agner Fog in Optimizing software in C++ and it reduces to how data is accessed and stored in the cache. For terms and detailed info, see the wiki entry on caching, I’m gonna narrow it down here. A cache is organized in sets and lines. At a time, only one set … Read more
Dependency analysis. The Go FAQ used to contain the following sentence: Go provides a model for software construction that makes dependency analysis easy and avoids much of the overhead of C-style include files and libraries. While the phrase is not in the FAQ anymore, this topic is elaborated upon in the talk Go at Google, … Read more
When you are using the unsorted list all tuples are accessed in memory-order. They have been allocated consecutively in RAM. CPUs love accessing memory sequentially because they can speculatively request the next cache line so it will always be present when needed. When you are sorting the list you put it into random order because … Read more
To answer this question, we’ll examine the assembly code produced by the X86 and X64 JITs for each of these cases. X86, if/then 32: foreach (int i in array) 0000007c 33 D2 xor edx,edx 0000007e 83 7E 04 00 cmp dword ptr [esi+4],0 00000082 7E 1C jle 000000A0 00000084 8B 44 96 08 mov eax,dword … Read more
this.id (as you know) this.value (on most input types. only issues I know are IE when a <select> doesn’t have value properties set on its <option> elements, or radio inputs in Safari.) this.className to get or set an entire “class” property this.selectedIndex against a <select> to get the selected index this.options against a <select> to … Read more
Here’s another vote for JMeter. JMeter is an open-source load testing tool, written in Java. It’s capable of testing a number of different server types (for example, web, web services, database, just about anything that uses requests basically). It does however have a steep learning curve once you start getting to complicated tests, but it’s … Read more
Summary: below 240, LLVM fully unrolls the inner loop and that lets it notice it can optimize away the repeat loop, breaking your benchmark. You found a magic threshold above which LLVM stops performing certain optimizations. The threshold is 8 bytes * 240 = 1920 bytes (your array is an array of usizes, therefore the … Read more
No two sites are alike. You really need to get a tool like jmeter and benchmark to see where your problem points will be. You can spend a lot of time guessing and improving, but you won’t see real results until you measure and compare your changes. For example, for many years, the MySQL query … Read more
Here is how you can test which piece of code is faster: % python -mtimeit “l=[]” 10000000 loops, best of 3: 0.0711 usec per loop % python -mtimeit “l=list()” 1000000 loops, best of 3: 0.297 usec per loop However, in practice, this initialization is most likely an extremely small part of your program, so worrying … Read more