Corey Goldberg

Python - Matplotlib and Numpy on Debian/Ubuntu

2012-01-29T12:38:01-08:00

There are `python-matplotlib` and `python-numpy` packages in the Debian/Ubuntu repos.

However, if you want to run in a virtualenv (with no-site-packages), and pip install these packages from PyPI, you need some system dependencies installed first to build with:

$ sudo apt-get install build-essential python-dev libfreetype6-dev libpng-dev python-virtualenv

Then, you can create a virtualenv, and the installers for Numpy and Matplotlib will work:

$ virtualenv env
$ cd env
$ source bin/activate
(env)$ pip install numpy matplotlib

...
...
Successfully installed numpy matplotlib
Cleaning up...

(tested on Ubuntu Oneiric 11.10 and Ubuntu Precise 12.04 alpha)

Officially Introducing "SST" (Python Web Test Framework)

2012-01-03T06:52:24-08:00

"SST (selenium-simple-test) is a framework built on Selenium WebDriver, using Python to make writing functional web tests easier with code."

Since early 2011, I have been working for Canonical on the Infrastructure Systems Development team (Core Dev Ops).

[pic of canonical-isd-hackers at UDS-P-Orlando]

A by-product of our recent development efforts is a web testing framework. It has been available on Launchpad for a while, but I've never really announced it in public. We are using SST internally, and I want to expose it to a wider audience.

What is Selenium WebDriver?

Selenium (WebDriver) is a popular open-source library for automating browsers. It can be used to create functional/acceptance tests of a web application. The Selenium client bindings provide API's that allow you to programatically drive a browser and access web content/elements. The bindings are available and supported for many languages and platforms.

While working directly with Selenium API's from code is fine for ad-hoc browser interaction, it is rather low-level and lacks things necessary for creating suites of automated web tests. For larger-scale testing, you will soon want to use a framework to help organize, execute, and report.

Introducing SST...

SST aims to keep things simple.

Tests are made up of scripts, created by composing actions that drive a browser and assert conditions. You have the flexibility of the full Python language, along with a convenient set of functions to simplify web testing.

SST framework consists of:

user actions and assertions (API) in Python
test case loader (generates/compiles scripts to unittest cases)
console test runner
data parameterization/injection
selectable output reports
selectable browsers
headless (xvfb) mode
screenshots on errors

Test output can be displayed to the console, saved as an HTML report, or JUnit-compatible XML for compatibility with CI systems.

SST is free open source software (Apache Licensed). SST is primarily being developed on Linux, specifically Ubuntu. It should work fine on other platforms, but any issues (or even better - patches) should be reported on the Launchpad project:

https://launchpad.net/selenium-simple-test

I just uploaded SST 0.1.0 to PyPI:

http://pypi.python.org/pypi/sst

go ahead, give it a try:

`$ [sudo] pip install sst`

documentation and more info:

http://testutils.org/sst

a sample test script in SST:

from sst.actions import *

go_to('http://www.ubuntu.com/')
assert_title_contains('Ubuntu homepage')

Here is the development progress of SST (shown as a code_swarm visualization) over the past 8 months:

Special thanks to all the SST code committers so far:

Danny Tamez
Julien Funk
Kenneth Koontz
Leo Arias
Lukasz Czyzykowkski
Rick McBride
Sidnei da Silva

Extra special thanks to SST's initial creator:

Michael Foord

Happy New Year!

-Corey Goldberg

"Web Performance Testing night" in Boston/Cambridge - Python Meetup Dec. 19

2011-12-21T08:46:12-08:00

I will be speaking at: "Web Performance Testing, lightning talks, and beers" at the Boston Python User Group.

Event Info: http://meetup.bostonpython.com/events/36664122/
Date: Monday, December 19, 2011, 7:00 PM
Location: Microsoft NERD, Cambridge, MA

"Corey Goldberg of Canonical and Dan Kuebrich of Tracelytics will tag-team to tell us about web performance testing, and a few interesting tools they've built."

Free pizza and beer!
Come Join!

Edit/Update:
Thanks to all who attended! The night was a big success.

The slides from my portion of the presentation are posted here:
webperf.html

Python - Stock Quotes From Google Finance

2011-09-27T05:46:17-07:00

Quick example of retrieving stock quotes from Google Finance in Python:

#!/usr/bin/env python

import json
import pprint
import urllib2


def get_stock_quote(ticker_symbol):   
    url = 'http://finance.google.com/finance/info?q=%s' % ticker_symbol
    lines = urllib2.urlopen(url).read().splitlines()
    return json.loads(''.join([x for x in lines if x not in ('// [', ']')]))


if __name__ == '__main__':
    quote = get_stock_quote('IBM')
    print 'ticker: %s' % quote['t']
    print 'current price: %s' % quote['l_cur']
    print 'last trade: %s' % quote['lt']
    print 'full quote:'
    pprint.pprint(quote)

* note: all values in the returned dict object are Unicode strings.

Output:

ticker: IBM
current price: 174.51
last trade: Sep 26, 4:00PM EDT
full quote:
{u'c': u'+5.17',
 u'ccol': u'chg',
 u'cp': u'3.05',
 u'div': u'0.75',
 u'e': u'NYSE',
 u'ec': u'0.00',
 u'eccol': u'chb',
 u'ecp': u'0.00',
 u'el': u'174.51',
 u'el_cur': u'174.51',
 u'elt': u'Sep 26, 6:07PM EDT',
 u'id': u'18241',
 u'l': u'174.51',
 u'l_cur': u'174.51',
 u'lt': u'Sep 26, 4:00PM EDT',
 u'ltt': u'4:00PM EDT',
 u's': u'2',
 u't': u'IBM',
 u'yld': u'1.72'}

Open Source Code Visualization With code_swarm (Canonical, Selenium, Couchbase)

2011-08-29T16:42:46-07:00

After a bit of hacking, I got code_swarm visualizations running on my Ubuntu 11.04 box. I'm capturing some pretty cool videos from source repos in git, bzr, and svn. Here are some of the more interesting code-base visualization videos I've made:

Python - Getting Started With Selenium WebDriver on Ubuntu/Debian

2011-07-11T09:48:33-07:00

This is a quick introduction to Selenium WebDriver in Python on Ubuntu/Debian systems.

WebDriver (part of Selenium 2) is a library for automating browsers, and can be used from a variety of language bindings. It allows you to programmatically drive a browser and interact with web elements. It is most often used for test automation, but can be adapted to a variety of web scraping or automation tasks.

To use the WebDriver API in Python, you must first install the Selenium Python bindings. This will give you access to your browser from Python code. The easiest way to install the bindings is via pip.

On Ubuntu/Debian systems, this will install pip (and dependencies) and then install the Selenium Python bindings from PyPI:

 
$ sudo apt-get install python-pip
$ sudo pip install selenium

After the installation, the following code should work:

 
#!/usr/bin/env python

from selenium import webdriver

browser = webdriver.Firefox()
browser.get('http://www.ubuntu.com/')

This should open a Firefox browser sessions and navigate to http://www.ubuntu.com/

Here is a simple functional test in Python, using Selenium WebDriver and the unittest framework:

 
#!/usr/bin/env python

import unittest
from selenium import webdriver


class TestUbuntuHomepage(unittest.TestCase):
    
    def setUp(self):
        self.browser = webdriver.Firefox()
        
    def testTitle(self):
        self.browser.get('http://www.ubuntu.com/')
        self.assertIn('Ubuntu', self.browser.title)
        
    def tearDown(self):
        self.browser.quit()


if __name__ == '__main__':
    unittest.main(verbosity=2)

Output:

 
testTitle (__main__.TestUbuntuHomepage) ... ok

----------------------------------------------------------------------
Ran 1 test in 5.931s

OK

Python - Reading MP3 Meta Information with 'mpeg1audio'

2011-07-09T10:25:26-07:00

'mpeg1audio' is a Pure Python MPEG Audio Layer 1, 2 and 3 meta information retrieval package. It is capable of retrieving duration, bitrate, average bitrate, sample count, etc.

Here is an example of using mpeg1audio for getting meta data from a directory of MP3 files.

Code:

 
#!/usr/bin/env python

import glob
import mpeg1audio  # (https://github.com/Ciantic/mpeg1audio/)

for f in sorted(glob.glob('*.mp3')):
    mp3 = mpeg1audio.MPEGAudio(f)
    mb = '%.2f' % (mp3.size / 1048576.0)
    fn = f.replace('.mp3', '')
    print '%s (%s) [%dk] %s MB' % (fn, mp3.duration, mp3.bitrate, mb)

Output:

 
Eminem - Buffalo Bill (0:03:56) [253k] 7.15 MB
Minor Threat - Betray (0:03:02) [180k] 3.92 MB
Social Distortion - Bakersfield (0:06:24) [320k] 14.68 MB
Social Distortion - Diamond In The Rough (0:04:34) [320k] 10.49 MB
Social Distortion - Prison Bound (0:05:24) [227k] 8.81 MB
Social Distortion - When She Begins (0:05:02) [320k] 11.54 MB

Python - processing GMail IMAP email

2011-07-07T14:34:40-07:00

Here is an example of processing your GMail IMAP email in Python.

The script below will:

login to GMail account using IMAP
open your Inbox
retrieve and print all messages
close mailbox
logout

#!/usr/bin/env python

import imaplib

USER = 'username@gmail.com'
PASSWORD = 'xxx'

mail = imaplib.IMAP4_SSL('imap.gmail.com', 993)
mail.login(USER, PASSWORD)
mail.select('Inbox')

status, data = mail.search(None, 'ALL')
for num in data[0].split():
    status, data = mail.fetch(num, '(RFC822)')
    print 'Message %s\n%s\n' % (num, data[0][1])
   
mail.close()
mail.logout()

Joined Google+

2011-07-05T09:39:36-07:00

I have an account on Google+
Go ahead and add me if you know me :)

Python - Taking Browser Screenshots With No Display (Selenium/Xvfb)

2011-07-04T10:41:18-07:00

In my last two blog posts, I showed examples of using Selenium WebDriver to capture screenshots, and running in a headless (no X-server) mode.

This example combines the two solutions to capture screenshots inside a virtual display.

To achieve this, I use a combination of Selenium WebDriver and pyvirtualdisplay (which uses xvfb) to run a browser in a virtual display and capture screenshots.

the setup you need is:

Selenium 2 Python bindings: PyPI
pyvirtualdisplay Python package (depends on xvfb): PyPI

On Debian/Ubuntu Linux systems, you can install everything with:

$ sudo apt-get install python-pip xvfb xserver-xephyr
$ sudo pip install selenium

once you have it setup, the following code example should work:

#!/usr/bin/env python

from pyvirtualdisplay import Display
from selenium import webdriver

display = Display(visible=0, size=(800, 600))
display.start()

browser = webdriver.Firefox()
browser.get('http://www.google.com')
browser.save_screenshot('screenie.png')
browser.quit()

display.stop()

this will:

launch a virtual display
launch Firefox browser inside the virtual display
navigate to google.com
capture and save a screenshot
close the browser
stop the virtual display

Python - Headless Selenium WebDriver Tests using PyVirtualDisplay

2012-01-02T07:25:19-08:00

I need to integrate my functional UI tests (Selenium/WebDriver) with my Jenkins CI system. The problem is that my Jenkins CI server has no display, so I must run my GUI tests in a headless X-server.

A colleague pointed me to PyVirtualDisplay, a Python wrapper for Xvfb and Xephyr.

This makes running headless Python Selenium/WebDriver tests very easy.

Here is some Python code showing WebDriver with a virtual display provided by Xvfb:

    
#!/usr/bin/env python

from pyvirtualdisplay import Display
from selenium import webdriver

display = Display(visible=0, size=(800, 600))
display.start()

# now Firefox will run in a virtual display. 
# you will not see the browser.
browser = webdriver.Firefox()
browser.get('http://www.google.com')
print browser.title
browser.quit()

display.stop()

install PyVirtualDisplay on Ubuntu/Debian:

$ sudo apt-get install xvfb python-pip
$ sudo pip install pyvirtualdisplay

Python - Selenium WebDriver - Capture Screenshot

2011-07-12T08:30:48-07:00

Example of capturing a screenshot from Selenium WebDriver in Python:

 
#!/usr/bin/env python
from selenium import webdriver

browser = webdriver.Firefox()
browser.get('http://www.ubuntu.com/')
browser.save_screenshot('screenie.png')
browser.quit()

selenium/webdriver bindings for Python: http://pypi.python.org/pypi/selenium

Ubuntu Developer Summit, Oneiric Ocelot

2011-05-15T07:55:59-07:00

I just got back from UDS-O (Ubuntu Developer Summit, Oneiric Ocelot) in Budapest, Hungary. It was my first UDS, and my first time in Eastern Europe.

I was really worried that the time-change and jet-lag going to eastern Europe would mess me up. However, I felt really good the entire trip and adjusted almost instantly. My mood was good and I was ready to hack.

Some quick comments about the summit:

Budapest was fun and interesting, with beautiful weather and historic architecture.
The Ubuntu summit is a very well run event, where important decisions are made and work gets done.
Our Community rocks!
Ubuntu rocks!

I was able to attend a few UDS sessions throughout the week, but my main mission was an on-site sprint with my team at Canonical (ISD). Our team is globally-distributed, and this was my first chance to meet and work with all of them in person. While the entire summit was awesome, my most lasting memories will be of sitting crammed in a hot hotel room with a dozen of the finest hackers/colleagues I have ever worked with. As a new member to ISD, they made me feel welcomed and let me jump right in.

Can't wait until next UDS!

Performance and Scalability Testing with Python and Multi-Mechanize

2011-03-31T06:28:03-07:00

I put together a slide-deck to help introduce Multi-Mechanize. I wanted something a little friendlier and easier to digest than "go read the project wiki". (It is also the basis of a presentation/talk I might give someday).

Hopefully, this will help people better understand what the project is all about.

Performance and Scalability Testing with Python and Multi-Mechanize

linux-metrics - Python Package - System Metrics/Stats for Linux

2011-03-22T06:20:24-07:00

I just released my Python package: 'linux-metrics'

linux-metrics contains Python modules for getting OS metrics on systems running the Linux (2.6) kernel. It is a pure python library with no external dependencies.

This project is under development, and nowhere near comprehensive. Only basic stats for major subsystems are provided (Processor/CPU, Disk, Memory, Network). Hopefully, more are coming.

Project Home: http://linux-metrics.googlecode.com
PyPI Entry: http://pypi.python.org/pypi/linux-metrics

Going to PyCon 2011!

2011-01-25T14:04:40-08:00

This year I am attending my first PyCon (the annual Python community conference).

I will be in Atlanta: March 10-13.

If anyone is interested in meeting up or collaborating while I'm there, get in touch:

Twitter: @cgoldberg
Homepage/Info: goldb.org

Python - Search a Local or Remote Splunk Server

2010-12-01T06:40:24-08:00

Some basic instructions for searching Splunk from Python...

First, you must install Splunk on the machine you will run the Python script from. Splunk installs its own Python interpreter that you can use to run your code. I am using Splunk 4.14, which includes Python 2.6.

(It looks like you can set some environment variables and install a few Python dependencies along with the Python SDK and get this going "outside" of Splunk. But the easiest option is just to run on their interpreter).

To run your own Python scripts on Splunk's interpreter:
- save script into Splunk's "bin" directory
(usually "/opt/splunk/bin" or "C:\Program Files\Splunk\bin")
- go to the "bin" directory and run:
splunk cmd python your_script.py

So...
What goes in your Python code?

First, import the modules you will need:

 
import time
import splunk.auth
import splunk.search

Next, authenticate and get a session key.

For the local splunk host:

 
key = splunk.auth.getSessionKey('user', 'password')

If you are going to search a remote splunk host, you must authenticate against it by adding the "hostPath" parameter:

 
key = splunk.auth.getSessionKey('user', 'password', hostPath='https://mysplunk:8089')

Tips:
- use https, even if you are not using ssl in your splunk web interface
- 'admin' user doesn't seem to work. user a normal user/password.

Next, submit a search job.

For a local search:

 
job = splunk.search.dispatch('search index="os" *', earliest_time='-15m')

For a remote search, use the "hostPath" parameter again:

 
job = splunk.search.dispatch('search index="os" *', earliest_time='-15m', hostPath='https://mysplunk:8089')

print the job details:

 
print job

wait for the results:

 
while not job.isDone:
    time.sleep(.25)

print results

 
for result in job.results:
    print result

Altogether in a Python script:

 
#!/usr/bin/env python
# Corey Goldberg - 2010
# 
#  search a remote splunk server
#
#  instructions:
#   - save script into splunk's "bin" directory
#     (usually "/opt/splunk/bin" or "C:\Program Files\Splunk\bin")
#   - go to the "bin" directory and run: 
#     $ splunk cmd python my_script.py
#



import time
import splunk.auth
import splunk.search



SPLUNK_SERVER = '192.168.12.173'
USER_NAME = 'foo'
PASSWORD = 'secret'
SEARCH_STRING = 'search index="os"'
EARLIEST_TIME = '-15m'



def main():
    # authenticate
    key = splunk.auth.getSessionKey(USER_NAME, PASSWORD, hostPath='https://%s:8089' % SPLUNK_SERVER)
    print 'auth key:\n%s' % key
    
    # submit a search job
    job = splunk.search.dispatch(SEARCH_STRING, earliest_time=EARLIEST_TIME, hostPath='https://%s:8089' % SPLUNK_SERVER)
    print 'job details:\n%s' % job

    # wait for results
    while not job.isDone:
        time.sleep(.25)
    
    print 'results:'    
    for result in job.results:
        print result
          
          

if __name__== '__main__':
    main()

Python - Shorten a URL Using Google's Shortening Service (goo.gl)

2010-10-08T09:02:44-07:00

Using Python to shorten a URL with Google's shortening service (goo.gl):

 
#!/usr/bin/python 
#  Corey Goldberg - 2010

import json
import urllib
import urllib2


def shorten(url):
    gurl = 'http://goo.gl/api/url?url=%s' % urllib.quote(url)
    req = urllib2.Request(gurl, data='')
    req.add_header('User-Agent', 'toolbar')
    results = json.load(urllib2.urlopen(req))
    return results['short_url']


if __name__ == '__main__':
    print shorten('http://www.goldb.org/')
    print shorten('www.yahoo.com')

You give it a URL to shorten: shorten('http://www.goldb.org/long_url')

... and it returns a shortened URL for you: 'http://goo.gl/jh4W'

Python - Linux: Parse Network Stats From ifconfig

2010-09-24T15:04:16-07:00

I needed to get some Linux networking stats in my Python program today. Specifically, I needed 'bytes sent' and 'bytes received' counts since last reboot from the local machine.

ifconfig is a network configuration utility for Linux that you run from the command line:

corey@studio17:~$ ifconfig eth0
eth0      Link encap:Ethernet  HWaddr 00:22:19:e5:07:31  
          inet addr:10.0.0.5  Bcast:10.0.0.255  Mask:255.255.255.0
          inet6 addr: fe80::222:19ff:fee5:731/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:3353822 errors:0 dropped:0 overruns:0 frame:0
          TX packets:3052408 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:3476310326 (3.4 GB)  TX bytes:256706611 (256.7 MB)
          Interrupt:17

The following function parses output from ifconfig to get the network stats I was after:

import re
import subprocess

def get_network_bytes(interface):
    output = subprocess.Popen(['ifconfig', interface], stdout=subprocess.PIPE).communicate()[0]
    rx_bytes = re.findall('RX bytes:([0-9]*) ', output)[0]
    tx_bytes = re.findall('TX bytes:([0-9]*) ', output)[0]
    return (rx_bytes, tx_bytes)

Example usage:

import re
import subprocess

def main():
    rx_bytes, tx_bytes = get_network_bytes('eth0')
    print '%s bytes received' % rx_bytes
    print '%s bytes sent' % tx_bytes
      
def get_network_bytes(interface):
    output = subprocess.Popen(['ifconfig', interface], stdout=subprocess.PIPE).communicate()[0]
    rx_bytes = re.findall('RX bytes:([0-9]*) ', output)[0]
    tx_bytes = re.findall('TX bytes:([0-9]*) ', output)[0]
    return (rx_bytes, tx_bytes)

if __name__ == '__main__':
    main()

Update: someone left an anonymous comment and mentioned you can just read from proc/net/dev rather than using ifconfig. I modified his code sample and came up with this:

def get_network_bytes(interface):
    for line in open('/proc/net/dev', 'r'):
        if interface in line:
            data = line.split('%s:' % interface)[1].split()
            rx_bytes, tx_bytes = (data[0], data[8])
            return (rx_bytes, tx_bytes)

Example Usage:

def main():
    rx_bytes, tx_bytes = get_network_bytes('eth0')
    print '%s bytes received' % rx_bytes
    print '%s bytes sent' % tx_bytes
      
def get_network_bytes(interface):
    for line in open('/proc/net/dev', 'r'):
        if interface in line:
            data = line.split('%s:' % interface)[1].split()
            rx_bytes, tx_bytes = (data[0], data[8])
            return (rx_bytes, tx_bytes)

if __name__ == '__main__':
    main()

My Chrome Users Now Outnumber Internet Explorer (Traffic Stats)

2010-09-23T08:07:38-07:00

I really like to analyze the traffic to my various websites (homepage, blog, project pages, open source code).

Since my visitors must be somewhat interested in what I post, I like to think they are *just* *like* *me*.

So... of course, my own personal web metrics are better than anything else out there :)
(to you they might be worthless, but to me they are gold)

I get a pretty steady stream of about 40k pageviews per month. In the past year, I've served a paltry half million pageviews. But hey, its a good enough sample size to work with, and pretty flattering to have attracted that many eyeballs.

Look what happened this past month:

(stats from aug_22_2010 - sept_21_2010)

Chrome visitors overtook Internet Explorer in site usage.

Here is how it has been playing out in the past year and a half:

(Notice my Firefox visitors are waning a little also.)

Python - Multi-Mechanize Script With HTTP Profiling Timers

2010-09-22T06:50:41-07:00

Multi-Mechanize is an open source framework for web performance and load testing. It allows you to run simultaneous python scripts to generate load (synthetic transactions) against a web site or web service.

The default response timer wraps the entire Transaction(), so it will time everything included. For more granular timing, you need to instrument your script code with custom timers.

Multi-Mechanize is pure Python and you have access to all of Python's standard library in your scripts. For example, you can use httplib to write a virtual user agent script and get detailed HTTP profiling times (TTFB, TTLB, etc). http://docs.python.org/library/httplib.html

 
import httplib
import time


class Transaction(object):
    def __init__(self):
        self.custom_timers = {}
    
    def run(self):
        conn = httplib.HTTPConnection('www.example.com')
        start = time.time()
        conn.request('GET', '/')
        request_time = time.time()
        resp = conn.getresponse()
        response_time = time.time()
        conn.close()     
        transfer_time = time.time()
        
        self.custom_timers['request sent'] = request_time - start
        self.custom_timers['response received'] = response_time - start
        self.custom_timers['content transferred'] = transfer_time - start
        
        assert (resp.status == 200), 'Bad HTTP Response'

To test it out, you can add this to the bottom of the script and run it from the command line:

 
if __name__ == '__main__':
    trans = Transaction()
    trans.run()
    
    for timer in ('request sent', 'response received', 'content transferred'):
        print '%s: %.5f secs' % (timer, trans.custom_timers[timer])

Output:

 
request sent: 0.14429 secs
response received: 0.25995 secs
content transferred: 0.26007 secs

* if you are running MS Windows, replace the time.time() calls with time.clock() for better timer accuracy. On all other operating systems, use time.time()

CSharp/.NET - Use Stopwatch() Instead of DateTime() for Accurate High Precision Timing

2010-09-20T06:37:34-07:00

(originally posted at coreygoldberg.blogspot.com)

In C# (.NET), the DateTime() class is not accurate for high precision timing. Instead, use the Stopwatch() class if you need a timer. Most hardware and operating systems support a high-resolution performance counter that can be accessed through System.Diagnostics.Stopwatch.

Don't use DateTime() like this if you need accuracy:

 
using System;

class Program
{
    public static void Main()
    {
        DateTime start = DateTime.Now;

            // do timed work here

        DateTime stop = DateTime.Now;

        // don't do this. you won't get accurate timing
        Console.WriteLine("{0} ms", (stop - start).TotalMilliseconds);

        // definitely don't do this. you won't get accurate timing or full timer resolution
        Console.WriteLine("{0} ms", (stop - start).Milliseconds);
    }
}

Stopwatch() uses operating system's high-resolution performance counter:

 
using System;
using System.Diagnostics;

class Program
{
    public static void Main()
    {
        Stopwatch stopWatch = Stopwatch.StartNew();

            // do timed work here

        stopWatch.Stop();

        // don't do this. you won't get full timer resolution
        Console.WriteLine("{0} ms", stopWatch.ElapsedMilliseconds);

        // do this to get accurate high precision timing
        Console.WriteLine("{0} ms", stopWatch.Elapsed.TotalMilliseconds);
    }
}

The Stopwatch class is in the System.Diagnostics namespace:

 
using System.Diagnostics;

Stopwatch measures elapsed time by counting timer ticks in the underlying timer mechanism. If the installed hardware and operating system support a high-resolution performance counter, then the Stopwatch class uses that counter to measure elapsed time. Otherwise, the Stopwatch class uses the system timer (DateTime class) to measure elapsed time.

To see if your system supports a high-resolution performance counter, check the Stopwatch.IsHighResolution property:

 
if (Stopwatch.IsHighResolution)
    Console.WriteLine("Using the system's high-resolution performance counter.");
else 
    Console.WriteLine("Using the DateTime class.");

To check the timing accuracy, use the Stopwatch.Frequency property:

 
long frequency = Stopwatch.Frequency;

Console.WriteLine("Timer frequency in ticks per second: {0}", frequency);

long nanosecPerTick = (1000L*1000L*1000L) / frequency;

Console.WriteLine("Timer is accurate within {0} nanoseconds", nanosecPerTick);

Load Testing Web Services with Python and Multi-Mechanize

2010-08-01T17:48:24-07:00

(originally posted at coreygoldberg.blogspot.com)

I had to test and benchmark a SOAP web service recently, and figured I'd write up some instructions for load testing with Multi-Mechanize.

Multi-Mechanize is a performance and load testing framework that enables you to write plugins (in Python) to create virtual user scripts that run in parallel against your service.

Project Home: multimechanize.com
Virtual User Script Development Guide: DevelopingScripts

Since Multi-Mechanize scripts are pure Python, you can use any Python module inside them. In the case of a web service that uses SOAP, you have a few options. You can use any 3rd party module, so something like Suds (a lightweight SOAP client lib) would be a reasonable choice. However, I decided to stick with the Python standard library and build my scripts with urllib2. Afterall, SOAP is just slinging a bunch of XML back-and-forth over HTTP.

So before I get started with Multi-Mechanize and performance/load testing...

Here is a Python (2.x) script using urllib2 to interact with a SOAP web service over HTTP:

import urllib2

with open('soap.xml') as f:
    soap_body = f.read()
    
req = urllib2.Request(url='http://www.foo.com/service', data=soap_body)
req.add_header('Content-Type', 'text/xml')
resp = urllib2.urlopen(req)
content = resp.read()

(The script above assumes you have a file named 'soap.xml' in the local directory that contains your payload (SOAP XML message). It will send an HTTP POST request containing your payload in the body.)

After the initial script is created in Python, the next step is to convert it into a Multi-Mechanize script. To do this, you create a Transaction class with a run() method and add your code there.

As a Multi-Mechanize script, the same thing would be done like this:

import urllib2


class Transaction(object):
    def __init__(self):
        with open('soap.xml') as f:
            self.soap_body = f.read()
    
    def run(self):
        req = urllib2.Request(url='http://www.foo.com/service', data=self.soap_body)
        req.add_header('Content-Type', 'text/xml')
        resp = urllib2.urlopen(req)
        content = resp.read()
        
        assert ('Example SOAP Response' in content), 'Failed Content Verification'

(Notice I also added an assert statement to verify the content returned from the service.)

Now that you have a script created, it's time to configure Multi-Mechanize and run some tests.

You can download Multi-Mechanize from: code.google.com
It requires Python 2.x (2.6 or 2.7), and if you want it to generate graphs, you must also install Matplotlib and its dependencies. See the FAQ for help.

Once you have Multi-Mechanize downloaded, unzip it and go to the "/projects" directory. You can create a new project directory here. You can call it "soap_project". Inside this directory, you will need 2 things: a config file ("config.cfg"), and a "test_scripts" directory (containing the script you previously created, which you can call "soap_client.py". Since the script is looking for a data file named "soap.xml", make sure you have one created in the main multi-mechanize directory.

The directory and file layout will look like this:

/multi-mechanize
    /lib
    /projects
        /soap_project
            /test_scripts
                soap_client.py
            config.cfg
    multi-mechanize.py
    soap.xml

(you can see the "default_project" for an example of how it should be setup.)

To begin with, you can use a simple config.cfg file like this:

[global]
run_time: 30
rampup: 0
console_logging: on
results_ts_interval: 10

[user_group-1]
threads: 1
script: soap_client.py

This will just a run a single thread of your virtual user script for 30 seconds; good enough for testing and getting things going.

To run a test, go to the topmost multi-mechanize directory and run:

$ python multi-mechanize.py soap_project

(You should see timer output in the console.)

Once you have things running well, you can turn off "console_logging" and increase the workload. It will take some adjustment and plenty of trials to get the load dialed in correctly for your service. You can also get a lot more sophisticated with your workload model and create multiple virtual user scripts doing different transactions. In this case, I'll keep it simple and just test one web service request type in isolation.

Once I ran plenty of iterations and got a feel for how the service responded and what its limits were, I settled with a config file like this:

[global]
run_time: 900
rampup: 900
console_logging: off
results_ts_interval: 90

[user_group-1]
threads: 30
script: soap_client.py

(30 threads, increasing load over 15 mins)

After each test run you do, a new results directory is created containing your test results. Look for "results.html" and view it in your browser to see the output report.

Have questions about Multi-Mechanize?
Post to the discussion group: groups.google.com/group/multi-mechanize

Rackspace Cloud - Outbound Bandwidth Caps, Network Too Slow

2010-07-27T09:11:47-07:00

Have you seen the network/bandwidth caps that Rackspace places on their cloud servers?

From the Rackspace Cloud Server FAQ:

"Your Cloud Server has a bandwidth cap that is applied in relation to the size of the server. Please note that the bandwidth caps are placed on outbound bandwidth only. Inbound bandwidth is not capped."

Server Size Public Limit ServiceNet Limit

256MB 10 Mbps 20 Mbps

512MB 20 Mbps 40 Mbps

1024MB 30 Mbps 60 Mbps

2048MB 40 Mbps 80 Mbps

4096MB 50 Mbps 100 Mbps

8192MB 60 Mbps 120 Mbps

15872MB 70 Mbps 140 Mbps

I was going to use the Rackspace Cloud to do some performance testing of a new server. I wanted to run 2 servers in a clustered mode, replicating data to each other. My first concern was the speed of the internal network interconnects between cloud nodes.

After doing some research, I realized the bandwidth caps make it a non-starter. 20-140 Mbps private interconnects?? That's not enough. I would saturate the network almost immediately, even on their largest server class. Sorry Rackspace.

In comparison, Amazon's EC2 Cloud offers High Performance Computing nodes with 10 Gigabit interconnects: Amazon HPC

WebInject - New Discussion Group Launched

2010-07-25T10:52:05-07:00

I just started a new discussion group for WebInject:

http://groups.google.com/group/webinject

The old forums (http://www.webinject.org/cgi-bin/forums/YaBB.cgi) have been broken for several years. I will leave them up in read-only mode, but some threads are broken and unviewable.

Feel free to post a message to this new discussion group.
questions, bugs, patches, collaboration, comments, welcome...

Updates and new development coming soon...

WebInject is a free tool for automated testing and monitoring of web applications or services. It can be used standalone, or as a plugin for external monitoring systems.

Server Size	Public Limit	ServiceNet Limit
256MB	10 Mbps	20 Mbps
512MB	20 Mbps	40 Mbps
1024MB	30 Mbps	60 Mbps
2048MB	40 Mbps	80 Mbps
4096MB	50 Mbps	100 Mbps
8192MB	60 Mbps	120 Mbps
15872MB	70 Mbps	140 Mbps

Corey Goldberg

Python - Matplotlib and Numpy on Debian/Ubuntu

Officially Introducing "SST" (Python Web Test Framework)

"Web Performance Testing night" in Boston/Cambridge - Python Meetup Dec. 19

Python - Stock Quotes From Google Finance

Open Source Code Visualization With code_swarm (Canonical, Selenium, Couchbase)

Canonical:

Selenium WebDriver:

Couchbase:

Python - Getting Started With Selenium WebDriver on Ubuntu/Debian

Python - Reading MP3 Meta Information with 'mpeg1audio'

Python - processing GMail IMAP email

Joined Google+

Python - Taking Browser Screenshots With No Display (Selenium/Xvfb)

Python - Headless Selenium WebDriver Tests using PyVirtualDisplay

Python - Selenium WebDriver - Capture Screenshot

Ubuntu Developer Summit, Oneiric Ocelot

Performance and Scalability Testing with Python and Multi-Mechanize

linux-metrics - Python Package - System Metrics/Stats for Linux

Going to PyCon 2011!

Python - Search a Local or Remote Splunk Server

Python - Shorten a URL Using Google's Shortening Service (goo.gl)

Python - Linux: Parse Network Stats From ifconfig

My Chrome Users Now Outnumber Internet Explorer (Traffic Stats)

Python - Multi-Mechanize Script With HTTP Profiling Timers

CSharp/.NET - Use Stopwatch() Instead of DateTime() for Accurate High Precision Timing

Load Testing Web Services with Python and Multi-Mechanize

Rackspace Cloud - Outbound Bandwidth Caps, Network Too Slow

WebInject - New Discussion Group Launched