wolfeidau

#!/usr/sbin/dtrace -s
/*
** execsnoop.d - snoop process execution as it occurs.
**     Written in DTrace (Solaris 10 build 51).
**
** NOTE: This version is deprecated. See "execsnoop",
**  http://www.brendangregg.com/dtrace.html
**
** 27-Mar-2004, ver 0.60
**

wolfeidau

Monitoring a process which was exec'd using the -c switch.

$ pfexec dtrace -n 'profile-97/pid == $target && arg1/{@[jstack(100, 8000)] = count(); } tick-60s { exit(0); }' -c node
dtrace: description 'profile-97' matched 2 probes
> dtrace: pid 79919 has exited


              node`ares__read_line
              node`_ZN4node10cares_wrapL10InitializeEN2v86HandleINS1_6ObjectEEE+0x6a

wolfeidau

exports.update = function (accumulator, value) {
    accumulator.n++;
    var delta = value - accumulator.mean;
    accumulator.mean += delta / accumulator.n;
    accumulator.m2 += delta * (value - accumulator.mean);
};

exports.variance = function (accumulator) {
    return accumulator.m2 / (accumulator.n - 1)
};

wolfeidau

#!/usr/bin/env node

var optimist = require('optimist');
var pkgInfo = require('../package.json');
var fs = require('fs');
var levelup = require('levelup')

var argv = optimist
    .alias('d', 'data')
    .describe('d', 'Data directory path')

wolfeidau

trogdor:lev markw$ node lev ../datum/temp/datum_store4/ 

compression = true
encoding = json
keyEncoding = json
valueEncoding = json
levelup version = 0.7.0-b02

...p/datum_store4/>
Encoding not compatible with json

wolfeidau

              0xaa7ffd
              0x99f9a9
              0x8f2e78
              0x8f3fd6
              0x8f4206
              0x9b35bb
              0x9bee50

wolfeidau

• Install a base server with open ssh server enabled.
• Update the OS.

sudo apt-get update
sudo apt-get upgrade

• Install developement tools.

wolfeidau

#Ninja Block Debugging

I am building a list of handy commands which I use to work out what the hell my block is doing.

Prerequisites

This is a list of handy system tools i install on my block.

sudo apt-get install lsof 

wolfeidau

Simulating slow networks

In this case I am testing slowing down traffic to 173.192.57.100 for http and https traffic.

sudo ipfw add pipe 1 ip from any to 173.192.57.100 out dst-port 443
sudo ipfw add pipe 1 ip from any to 173.192.57.100 out dst-port 80

Apply a bandwidth restriction of 10KB/sec on the pipe assocated with the previously listed rules.

wolfeidau

$ traceroute gstatic.com
traceroute to gstatic.com (X.X.X.X), 64 hops max, 52 byte packets
 1  fritz.box (X.X.X.X)  2.194 ms  1.726 ms  1.758 ms
 2  lns20.mel4.on.ii.net (150.101.212.44)  31.827 ms  32.679 ms  32.132 ms
 3  te2-2.cor3.mel4.on.ii.net (150.101.208.65)  32.543 ms  33.445 ms  31.714 ms
 4  ae2.br1.syd7.on.ii.net (150.101.33.28)  48.787 ms  45.817 ms  49.045 ms
 5  gw.google.com (150.101.199.234)  44.229 ms  45.947 ms  44.794 ms
 6  66.249.95.224 (66.249.95.224)  45.787 ms  45.331 ms  45.238 ms
 7  72.14.237.135 (72.14.237.135)  46.175 ms  45.975 ms  45.514 ms
 8  syd01s12-in-f15.1e100.net (74.125.237.111)  44.155 ms  45.800 ms  44.944 ms