I screwed up using git ("git checkout --" on the wrong file) and managed to delete the code I had just written... but it was still running in a process in a docker container. Here's how I got it back, using https://pypi.python.org/pypi/pyrasite/ and https://pypi.python.org/pypi/uncompyle6
apt-get update && apt-get install gdb
Disclaimer: This piece is written anonymously. The names of a few particular companies are mentioned, but as common examples only.
This is a short write-up on things that I wish I'd known and considered before joining a private company (aka startup, aka unicorn in some cases). I'm not trying to make the case that you should never join a private company, but the power imbalance between founder and employee is extreme, and that potential candidates would
FWIW: I (@rondy) am not the creator of the content shared here, which is an excerpt from Edmond Lau's book. I simply copied and pasted it from another location and saved it as a personal note, before it gained popularity on news.ycombinator.com. Unfortunately, I cannot recall the exact origin of the original source, nor was I able to find the author's name, so I am can't provide the appropriate credits.
| library(XML) | |
| library(uuid) | |
| library(stringr) | |
| library(plyr) | |
| library(reshape2) | |
| library(ggplot2) | |
| f <- "https://raw.githubusercontent.com/chris-taylor/USElection/master/data/electoral-college-votes.csv" | |
| electoral.college <- read.csv(f, header=FALSE) | |
| names(electoral.college) <- c("state", "electoral_votes") |
| /*<?php | |
| //*/public class PhpJava { public static void main(String[] args) { System.out.printf("/*%s", | |
| //\u000A\u002F\u002A | |
| class PhpJava { | |
| static function main() { | |
| echo(//\u000A\u002A\u002F | |
| "Hello World!"); | |
| }} | |
| //\u000A\u002F\u002A | |
| PhpJava::main(); |
It's now here, in The Programmer's Compendium. The content is the same as before, but being part of the compendium means that it's actively maintained.
| // Since `overlapArea` function is monotonic increasing, we can perform a | |
| // simple bisection search to find the distance that leads to an overlap | |
| // area within epsilon of the desired overlap. | |
| function distanceForOverlapArea(r1, r2, desiredOverlap) { | |
| // Ensure r1 <= r2 | |
| if (r1 > r2) { | |
| var temp = r2; | |
| r2 = r1; | |
| r1 = temp; | |
| } |
Flame graphs are a nifty debugging tool to determine where CPU time is being spent. Using the Java Flight recorder, you can do this for Java processes without adding significant runtime overhead.
Shivaram Venkataraman and I have found these flame recordings to be useful for diagnosing coarse-grained performance problems. We started using them at the suggestion of Josh Rosen, who quickly made one for the Spark scheduler when we were talking to him about why the scheduler caps out at a throughput of a few thousand tasks per second. Josh generated a graph similar to the one below, which illustrates that a significant amount of time is spent in serialization (if you click in the top right hand corner and search for "serialize", you can see that 78.6% of the sampled CPU time was spent in serialization). We used this insight to spee
| /** | |
| * Solves the n-Queen puzzle in O(n!) | |
| * Let p[r] be the column of the queen on the rth row (must be exactly 1 queen per row) | |
| * There also must be exactly 1 queen per column and hence p must be a permuation of (0 until n) | |
| * There must be n distinct (col + diag) and n distinct (col - diag) for each queen (else bishop attacks) | |
| * @return returns a Iterator of solutions | |
| * Each solution is an array p of length n such that p[i] is the column of the queen on the ith row | |
| */ | |
| def nQueens(n: Int): Iterator[Seq[Int]] = | |
| (0 until n) |