talonx

Statement : Average distance of values from the mean is always 0.

Proof : Let values be n1, n2, n3....nn.

Then mean M = (sum (ni | i = 1 to n))/n

Average distance of values from mean 
= ( (M - n1) + (M - n2) ... + (M-nn) ) / n
= ( M x n  - (n1 + n2 + .... nn) ) / n
= M -  (sum (ni | i = 1 to n))/n

talonx

http://stats.stackexchange.com/questions/118/standard-deviation-why-square-the-difference-instead-of-taking-the-absolute-valu

http://math.stackexchange.com/questions/4787/motivation-behind-standard-deviation

http://mathoverflow.net/questions/1048/why-is-it-so-cool-to-square-numbers-in-terms-of-finding-the-standard-deviation/1092#1092

http://www.leeds.ac.uk/educol/documents/00003759.htm

talonx

#!/usr/bin/env ruby

instance_name = ARGV[0]
abort "Please specify an instance name" unless instance_name and instance_name.length > 0

instance_info, selected_instance = {}, nil
info_keymap = {2 => :ami_id, 3 => :address, 5 => :status, 6 => :keypair_name}

instances = `ec2-describe-instances`.split("\n").map{|l| l.split("\t")}
instances.each do |line|

talonx

In a perfect world, where things are done well, not just quickly, I would expect to find the following when joining the company:

Documentation

• Accurate / up-to-date systems architecture diagram

• Accurate / up-to-date network diagram

• Out-of-hours support plan

• Incident management plan

talonx

package main

import (
	"fmt"
	"io"
	"os"
	"strings"
)

type rot13Reader struct {

talonx

package main

import (
	"golang.org/x/tour/tree"
	"fmt"
)

// Walk walks the tree t sending all values
// from the tree to the channel ch.
func Walk(t *tree.Tree, ch chan int) {

talonx

Orien is correct, it is the fork() system call triggered by ProcessBuilder or Runtime.exec or other means of the JVM executing an external process (e.g. another JVM running ant, a git command, etc.).

There have been some posts on the Jenkins mailing lists about this: Cannot run program "git" ... error=12, Cannot allocate memory

There is a nice description of the issue on the SCons dev list: fork()+exec() vs posix_spawn()

There is a long standing JVM bug report with solutions: Use posix_spawn, not fork, on S10 to avoid swap exhaustion. But I'm not sure if this actually made it into JDK7 as the comments suggest was the plan.

In summary, on Unix-like systems, when one process (e.g. the JVM) needs to launch another process (e.g. git) a system call is made to

talonx

curl --verbose --user admin:admin -d '{"hello:input": { "name":"talonx"}}'  -H "Content-Type: application/json"   "http://localhost:8181/restconf/operations/hello:hello-world"

talonx

import scala.collection.mutable.Map

object reduce {

    def reduceByKey(func: (Int, Int) => Int, pairs: List[(String, Int)]): Map[String, Int] = {
        val ret = Map[String, Int]()

        for (tup <- pairs) {
            val k = tup._1
            val v = tup._2

talonx

---
- name: Capture files in path and register
  shell: >
    ls -1 /path/to/files
  register: files

- name: Remove files except specified
  file:
    path: "/path/to/files/{{ item }}"
    state: absent