Apache Benchmark: Stress-Test Apache With ab

Posted by Rakesh under Research, Technology

I’ve been having some issues with Apache lately in that it and MySQL aren’t playing nicely performance-wise. I’ve raised meaningful numbers. I’ve raised, lowered, raised, lowered, deleted, added, moved, and raised meaningless numbers. I’ve done a lot.

In the end, “time wget” gets you only so far when it comes to seeing how fast a page loads. Once you get Apache doing its job, it’s down to the database and the PHP code that’s running it all and that can get real fun to test.

Happily, Apache includes a very useful tool (in my experience) for hammering the living hell out of a server. It’s called Apache Benchmark (“ab” is the binary’s name) and it can really hand a server it’s own ass if you don’t watch it.

ab -kc 10 -t 30 http://localhost/

That will open 10 connections, use Keep-Alive on them, and then hammer localhost for 30 seconds through those connections. When done, you get a pretty little chart telling you what broke and how long it took to start screaming. Try fifty KA connections for five minutes if you really feel sadistic. That’d be equal to a very high-end hammering from Fark or Slashdot. Watch your server cry.

For best results, though, use it on another machine. You want to not only test the network connection but also leave the server’s CPU and OS to think about serving, not about pulling it down as well.

ab is included in Mac OS X as a part of the built-in Apache-based PWS.

If you want to hide your IP address (in order to protect your privacy) then you can send multiple requests to specific sites / webpages in specific time span via Proxy Server. You just release the following command from the commandline (Apache Server must be installed on your computer):

rakesh@debian ~]$ ab -kc 10 -t 30 -X 128.119.41.210:3128 http://localhost

Whereas:

ab Apache Benchmark

-k Enable the HTTP KeepAlive feature, i.e., perform multiple requests within one HTTP session.

-c Number of multiple requests to perform at a time. Default is one request at a time.

-X Use a proxy server for the requests.

-t timelimit: Maximum number of seconds to spend for benchmarking.

For option please read the manual.

Manual for Apache Benchmark tool:

NAME
ab – Apache HTTP server benchmarking tool

SYNOPSIS
ab [ -A auth-username:password ] [ -c concurrency ] [ -C cookie-name=value ] [ -d ] [ -e csv-file ] [ -g gnuplot-file ] [ -h ] [ -H custom-header
] [ -i ] [ -k ] [ -n requests ] [ -p POST-file ] [ -P proxy-auth-username:password ] [ -q ] [ -s ] [ -S ] [ -t timelimit ] [ -T content-type ]
[ -v verbosity] [ -V ] [ -w ] [ -x

-attributes ] [ -X proxy[:port] ] [ http://]host‐name[:port]/path ]

SUMMARY
ab is a tool for benchmarking your Apache Hypertext Transfer Protocol (HTTP) server. It is designed to give you an impression of how your current
Apache installation performs. This especially shows you how many requests per second your Apache installation is capable of serving.

OPTIONS
-A auth-username:password
Supply BASIC Authentication credentials to the server. The username and password are separated by a single : and sent on the wire base64
encoded. The string is sent regardless of whether the server needs it (i.e., has sent an 401 authentication needed).

-c concurrency
Number of multiple requests to perform at a time. Default is one request at a time.

-C cookie-name=value
Add a Cookie: line to the request. The argument is typically in the form of a name=value pair. This field is repeatable.

-d Do not display the “percentage served within XX [ms] table”. (legacy support).

-e csv-file
Write a Comma separated value (CSV) file which contains for each percentage (from 1% to 100%) the time (in milliseconds) it took to serve
that percentage of the requests. This is usually more useful than the ’gnuplot’ file; as the results are already ’binned’.

-g gnuplot-file
Write all measured values out as a ’gnuplot’ or TSV (Tab separate values) file. This file can easily be imported into packages like Gnu‐
plot, IDL, Mathematica, Igor or even Excel. The labels are on the first line of the file.

-h Display usage information.

-H custom-header
Append extra headers to the request. The argument is typically in the form of a valid header line, containing a colon-separated field-value
pair (i.e., “Accept-Encoding: zip/zop;8bit”).

-i Do HEAD requests instead of GET.

-k Enable the HTTP KeepAlive feature, i.e., perform multiple requests within one HTTP session. Default is no KeepAlive.

-n requests
Number of requests to perform for the benchmarking session. The default is to just perform a single request which usually leads to non-rep‐
resentative benchmarking results.

-p POST-file
File containing data to POST.

-P proxy-auth-username:password
Supply BASIC Authentication credentials to a proxy en-route. The username and password are separated by a single : and sent on the wire
base64 encoded. The string is sent regardless of whether the proxy needs it (i.e., has sent an 407 proxy authentication needed).

-q When processing more than 150 requests, ab outputs a progress count on stderr every 10% or 100 requests or so. The -q flag will suppress
these messages.

-s When compiled in (ab -h will show you) use the SSL protected https rather than the http protocol. This feature is experimental and very
rudimentary. You probably do not want to use it.

-S Do not display the median and standard deviation values, nor display the warning/error messages when the average and median are more than
one or two times the standard deviation apart. And default to the min/avg/max values. (legacy support).

-t timelimit
Maximum number of seconds to spend for benchmarking. This implies a -n 50000 internally. Use this to benchmark the server within a fixed
total amount of time. Per default there is no timelimit.
-T content-type
Content-type header to use for POST data.

-v verbosity
Set verbosity level – 4 and above prints information on headers, 3 and above prints response codes (404, 200, etc.), 2 and above prints
warnings and info.

-V Display version number and exit.

-w Print out results in HTML tables. Default table is two columns wide, with a white background.

-X proxy[:port]
Use a proxy server for the requests.

Git : Getting it — Fast Version Control System

Posted by Rakesh under Research, Technology, Work

Git is a free & open source, distributed version control system designed to handle everything from small to very large projects with speed and efficiency.

Every Git clone is a full-fledged repository with complete history and full revision tracking capabilities, not dependent on network access or a central server. Branching and merging are fast and easy to do.

Git is used for version control of files, much like tools such as Mercurial, Bazaar, Subversion, CVS, Perforce, and Visual SourceSafe.

Why Linus name it Git…

Linus Torvalds has quipped about the name “git”, which is British English slang for a stupid or unpleasant person: “I’m an egotistical bastard, and I name all my projects after myself. First Linux, now git.” This self-deprecating humor is tongue-in-cheek, as Torvalds was actually pressured into naming Linux after himself.

How Git started…

Git development began after many Linux kernel developers were forced to give up access to the proprietary BitKeeper system. The ability to use BitKeeper free of charge had been withdrawn by the copyright holder Larry McVoy after he claimed Andrew Tridgell had reverse engineered the BitKeeper protocols in violation of the BitKeeper license. At Linux.Conf.Au 2005, Tridgell demonstrated during his keynote that the reverse engineering process he had used was simply to telnet to the appropriate port of a BitKeeper server and type “help”.

Torvalds wanted a distributed system that he could use like BitKeeper, but none of the available free systems met his needs, particularly his performance needs.

Torvalds design criteria…

1. Take CVS as an example of what not to do; if in doubt, make the exact opposite decision. To quote Torvalds, speaking somewhat tongue-in-cheek.

2. Support a distributed, BitKeeper-like workflow

3. Very strong safeguards against corruption, either accidental or malicious

4. Very high performance

Design…

Git’s design was inspired by BitKeeper and Monotone. Git was originally designed as a low-level version control system engine on top of which others could write front ends, such as Cogito or StGIT. However, the core Git project has since become a complete revision control system that is usable directly.

Git Quick Start…

Cloning and Creating a Patch…

$ git clone git://github.com/git/hello-world.git

$ cd hello-world

$ (edit files)

$ git add (files)

$ git commit -m ‘Explain what I changed’

$ git format-patch origin/master

Creating and Commiting….

$ cd (project-directory)

$ git init

$ (add some files)

$ git add .

$ git commit -m ‘Initial commit’

Developed…

Original author: Linus Torvalds

Developer: Junio Hamano, Linus Torvalds

Stable release: 1.6.4.2 (2009-08-29; 44 hours ago) [+/−]

Written in: C, Bourne Shell, Perl

Operating system: POSIX

Type: Revision control

License: GNU General Public License v2

Website: http://git-scm.com