qiao hai-jun qiaohaijun

Lies, Damned Lies and Benchmarks

This is just an exercise to measure the performance between Sinatra-like libraries in:

Elixir v0.4.dev (running on top of the Erlang VM R14B03) with Dynamo;
Ruby 1.9.2 with [Sinatra Synchrony] v0.0.3 (https://github.com/kyledrake/sinatra-synchrony) + Thin;
node.js 0.4.7 with [express] v2.3.10(https://github.com/visionmedia/express)

We were discussing the design of an HA environment for Puppet, and what the potential impacts were of a "split-brain" situation. For the model that I was discussing...

...the "worst case" scenario is probably that the two Postgres databases become out-of-sync. This would require a network interruption that would cause:

the two front-end Puppet masters to lose contact with each other, causing both assume the master role, with the result that pgpool would be running on both nodes and each puppetdb process would be talking to it's local pgpool instance.
pgpool on one of the nodes to lose contact with the current master database server, causing it to erroneously promote the slave database.
some puppet clients in the environment to see one master and others to see the other master

Google面试题：扔鸡蛋问题

原题描述

两个软硬程度一样但未知的鸡蛋，它们有可能都在一楼就摔碎，也可能从一百层楼摔下来没事。有座100层的建筑，要你用这两个鸡蛋通过最少的次数确定哪一层是鸡蛋可以安全落下的最高位置。可以摔碎两个鸡蛋

方法分析

看到这个题目，最保险的方法就是一层一层试验，但这样只需要一个鸡蛋就可以了。我们现在有两个鸡蛋，完全可以用有更快的方法。

需要修改一下/etc/yum.repos.d/epel-7.repo

gpgcheck=0
enabled=1

这两项修改一下

安装服务软件

Machine Setup August 2016

Linux Ubuntu 2016.

1080 GTX
SDK 8.0
CuDNN 5.1

ENABLE Core dumps

ulimit -c unlimited

Install tmux

brew install tmux

Start tmux (https://gitlab.com/gnachman/iterm2/wikis/TmuxIntegration)

Run tmux -CC or tmux -CC attach in iTerm2 and then menu is shown on terminal:

ESC to detach
C to run commands
X to force quit
L for log

	1.1335086e+00, 1.0653587e+00, 8.4250325e-01, 7.0782984e-01, 1.0178784e+00, 1.2476827e+00, 9.0000000e-01
	1.1645714e+00, 1.1355961e+00, 5.5885374e-01, 7.9370192e-01, 1.0346794e+00, 1.0067861e+00, 9.0000000e-01
	1.0315895e+00, 1.1533842e+00, 4.2572016e-01, 1.0558440e+00, 1.1640420e+00, 7.1297054e-01, 9.0000000e-01
	7.9058261e-01, 1.0678134e+00, 7.5043060e-01, 1.2000510e+00, 1.0670009e+00, 5.0349420e-01, 9.4136145e-01
	6.3878936e-01, 8.1349649e-01, 9.7291951e-01, 1.2998549e+00, 1.0026658e+00, 5.8392542e-01, 1.1188041e+00
	6.4385427e-01, 6.6246660e-01, 9.3785503e-01, 1.1857500e+00, 7.7000347e-01, 9.4327347e-01, 1.2161867e+00
	9.7290237e-01, 6.2210481e-01, 1.0653587e+00, 8.4250325e-01, 7.0782984e-01, 1.0178784e+00, 1.2476827e+00
	1.1330941e+00, 9.3890430e-01, 1.1355961e+00, 5.5885374e-01, 7.9370192e-01, 1.0346794e+00, 1.0067861e+00
	1.1738960e+00, 1.1287058e+00, 1.1533842e+00, 4.2572016e-01, 1.0558440e+00, 1.1640420e+00, 7.1297054e-01
	1.2210669e+00, 1.1699535e+00, 1.0678134e+00, 7.5043060e-01, 1.2000510e+00, 1.0670009e+00

	#!/usr/bin/ruby

	require 'json'
	require 'emr/common'
	require 'digest'
	require 'socket'

	def run(cmd)
	if ! system(cmd) then
	raise "Command failed: #{cmd}"

	git config --global https.proxy http://127.0.0.1:1080

	git config --global https.proxy https://127.0.0.1:1080

	git config --global --unset http.proxy

	git config --global --unset https.proxy


	npm config delete proxy