The performance boost that your friend mentioned is probably too trivial compared to the amount of performance boost (through other factors) using a CSS file. Using the style attribute, the browser only paints the rule for that particular element, which in this case is the <div> element. This reduces the amount of look up time … Read more
Your n/2 + n/3 + n/5 + … n/97 is not O(n), because the number of terms is not constant. [Edit after your edit: O(n2) is too loose an upper bound.] A loose upper-bound is n(1+1/2+1/3+1/4+1/5+1/6+…1/n) (sum of reciprocals of all numbers up to n), which is O(n log n): see Harmonic number. A more … Read more
Just tested latency from Java on my Corei5 2.8GHz, only single byte send/received, 2 Java processes just spawned, without assigning specific CPU cores with taskset: TCP – 25 microseconds Named pipes – 15 microseconds Now explicitly specifying core masks, like taskset 1 java Srv or taskset 2 java Cli: TCP, same cores: 30 microseconds TCP, … Read more
My previous answer was partial and not well documented, here is an update with a summary of the solutions from it and from others in the discussion. The solutions are ordered from best solution to worst but also from the solution needing the most control over the web server to the one needing the less. … Read more
In simple terms, to scale horizontally is adding more servers. Vertically to increase the resources of the server. You can find more info on Wikipedia.
At my job, we use UUID as PKs. What I can tell you from experience is DO NOT USE THEM as PKs (SQL Server by the way). It’s one of those things that when you have less than 1000 records it;s ok, but when you have millions, it’s the worst thing you can do. Why? … Read more
The answers so far are spot-on. Using isset in this case is faster because It uses an O(1) hash search on the key whereas in_array must check every value until it finds a match. Being an opcode, it has less overhead than calling the in_array built-in function. These can be demonstrated by using an array … Read more
It’s better to avoid ambiguous terms like “increasing” or “decreasing” as it’s not clear if equality is acceptable or not. You should always use either for example “non-increasing” (clearly equality is accepted) or “strictly decreasing” (clearly equality is NOT accepted). def strictly_increasing(L): return all(x<y for x, y in zip(L, L[1:])) def strictly_decreasing(L): return all(x>y for … Read more
As many people pointed out the hashCode() method was to blame. It was only generating around 20,000 codes for 26 million distinct objects. That is an average of 1,300 objects per hash bucket = very very bad. However if I turn the two arrays into a number in base 52 I am guaranteed to get … Read more
The second one is about 25% faster in my mini-benchmark. public class ScratchPad { static String a; public static void main( String[] args ) throws Exception { long time = System.currentTimeMillis(); for( int i = 0; i < 10000000; i++ ) { StringBuilder sb = new StringBuilder(); sb.append( “someString” ); sb.append( “someString2″+i ); sb.append( “someStrin4g”+i … Read more