All posts by Ruturaj Vartak

Web, Linux, MySQL

Redis, Memcached, Tokyo Tyrant and MySQL comparision

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I wanted to compare the following DBs, NoSQLs and caching solutions for speed and connections. Tested the following

My test had the following criteria

  • 2 client boxes
  • All clients connecting to the server using Python
  • Used Python’s threads to create concurrency
  • Each thread made 10,000 open-close connections to the server
  • The server was
    • Intel(R) Pentium(R) D CPU 3.00GHz
    • Fedora 10 32bit
    • Intel(R) Pentium(R) D CPU 3.00GHz
    • 2.6.27.38-170.2.113.fc10.i686 #1 SMP
    • 1GB RAM
  • Used a md5 as key and a value that was saved
  • Created an index on the key column of the table
  • Each server had SET and GET requests as a different test at same concurrency

Results please !

Work sheet

throughput set

throughput get

I wanted to simulate a situation where I had 2 servers (clients) serving my code, which connected to the 1 server (memcached, redis, or whatever). Another thing to note was that I used Python as the client in all the tests, definately the tests would give a different output had I used PHP. Again the test was done to check how well the clients could make and break the connections to the server, and I wanted the overall throughput after making and breaking the connections. I did not monitor the response times. I didnt change absolutely any parameters for the servers, eg didn’t change the innodb_buffer_pool_size or key_buffer_size.

MySQL

MySQL lacked the whole scene terribly, I monitored the MySQL server via the MySQL Administrator and found that hardly there were any conncurrent inserts or selects, I could see the unauthenticated users, which meant that the client had connected to MySQL and was doing a handshake using MySQL authentication (using username and password). As you could see I didn’t even perform the 40 and 60 thread tests.

I truncated the table before I swtiched my tests from MyISAM to InnoDB. And always started the tests from lesser threads. My table was as follows

CREATE TABLE `comp_dump` (
  `k` char(32) DEFAULT NULL,
  `v` char(32) DEFAULT NULL,
  KEY `ix_k` (`k`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1

NoSQL

For Tokyo Tyrant I used a file.tch as the DB, which is a hash database. I also tried MongoDB as u may find if u have opened the worksheet, But the server kept failing or actually the mongod failed after coming at an unhandled Exception. I found something similar over here. I tried 1.0.1, 1.1.3 and the available Nightly build, but all failed and I lost my patience.

Now what

If you need speed just to fetch a data for a given combination or key, Redis is a solution that you need to look at. MySQL can no way compare to Redis and Memcache. If you find Memcache good enough, you may want to look at Tokyo Tyrant as it does a synchronous writes. But you need to check for your application which server/combination suits you the best. In Marathi there is a saying “मेल्या शिवाय स्वर्ग दिसत नाही”, which means “You can’t see heaven without dieing” or need to do your hard work, can’t escape that 😉

I’ve attached the source code used to test, if anybody has any doubts, questions feel free to ask

Web

How sessions work in PHP

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HTTP is a stateless protocol. Which means that every request the browser makes to the server cant be identified by the server as a subsequent request of that user/IP/browser or a brand new request.

HTTP doesn’t understand who is requesting. So how do sessions manage to make HTTP look intelligent? The Answer lies in the request-response model with data.


When a normal request is made, eg my website, the minimalistic data passed by the client/browser is this

GET / HTTP/1.1
Host: ruturaj.net

The server responds by giving the output. But when a developer does a session_start();, What actually happens is, the PHP engine sets a PHPSESSID cookie. This data is sent from the Server as Set-Cookie header. So the response goes somewhat like this

HTTP/1.x 200 OK
Date: xxxx
Set-Cookie: PHPSESSID=<32charhexvalue>; expires=xxxx
...

Now considering the browser does accept the cookies, it saves the PHPSESSID cookie. Consequently the server also creates a file in the specified directory (by default on Linux as /tmp) as /tmp/sess_32charid.

Now when another request is made by the user/browser, the Cookie header is passed through the GET request back to the server, something like this…

GET /session2.php HTTP/1.1
Host: ruturaj.net
Cookie: PHPSESSID=<32charid>; othercookies=othervalues;

The session2.php, for example, is setting a value of name in session, by this

$_SESSION['name'] = $name_obtained_from_somewhere;

Now as the script finishes, the script flushes all the $_SESSION data into the /tmp/sess_32charid file associated to that session id. It saves all the data in the serialized format

Consider the browser makes another request to session3.php where $_SESSION['name'] is echoed. Now when the request is made, just like previous case, the PHPSESSID is passed in the cookie.

Now as mandated by php.net, that every page where sessions should be needed, a session_start(); is required. So as soon this function is invoked, PHP checks if the browser’s request had any PHPSESSID cookie sent in the header, as it was sent in our case, PHP Engine will open /tmp/sess_32charid file (with the same session id) and unserialize the contents of the file. It then assigns the values of the unserialized data structures to the $_SESSION variable.

The simple echo $_SESSION['name']; will now be able to output the name!! Sessions working…

On a session_destroy();, PHP sends a destructive, previous timestamp cookie for PHPSESSID and unlinks or deletes the /tmp/sess_32charid file. This ensures that no reference of that session is left.

References

  • http://in3.php.net/manual/en/session.configuration.php
Trek

Siddhagad Trek

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Monsoons had just arrived and we couldn’t resist the first one of the wet season, Siddhagad. Located near Murbad, between Gorakhgad and Bhimashankar, it was a good outing for us, Vj, Mallik, R.A. Jo B.A, Sneha, Swati and Kudrat. We could’ve hiked the final Balekilla, but as we were on a tight one-day schedule, we had to reach up to the cave atop the Siddhagad machi and return back.

Siddhagad Photos
Siddhagad Photos

Travelling Directions

  • Get a train for Kalyan Railway Station (Central Railway)
  • A ST bus to Murbad
  • Another ST bus to Narivali
  • A walk starts which converts to a trek soon – towards Siddhagad

Approximate time of Trek: 6-7 hrs (including the return to the base village)

guitar

Hai junoon – New York | Guitar Chords

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This entry is part 12 of 42 in the series Guitar

This new song, is not very different in strumming or chords, runs in the scale of D, with Dsus4 to add higher note and moves in D, A and G.

Intro

D ... D

sus4

A ... A

sus4

Song

Na .. Na nana na na na
D             D

sus4

  A
Nana na na na na
              G
Nanana na na na
             A

Yaaron ji bhar ke ji le pal
D                D

sus4

  A
lagta hai aaj kal
              G
daur apna aayegaa
              A

yaaron khud pe ho yakeen
D              D

sus4

  A
toh zindagi haseen
              G
tujhe kal bulayegaa
                A

Strumming

Down ... Down Down Up Up Down Up Down

The strumming pattern is a little cagey, modifications appreciated.

Linux

Fedora 11 on Acer 4736Z

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I finally managed to get a new Laptop, Acer 4736Z. I’d to wait before Fedora 11’s download was complete and I could install it.

Overview

  • Graphics card works out of the box (1366×768 resolution)
  • Sound is detected well
  • Wireless and bluetooth are working
  • The Web Camera is detected and working well
  • The Brightness control doesn’t work
  • The gsynaptics had to be installed to enable tap on the touchpad

All and all it looks good. Here is a screenshot.
Fedora 11 on Acer 4736Z

Pulseaudio CPU usage
Great work, Pulseaudio in F11 uses lesser CPU as compared to Fedora 10 Pulse Audio

Linux

Fedora 10 Pulse Audio High CPU Usage

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Guys using Fedora 10, must’ve seen this problem of Pulseaudio taking high CPU usage. After a lot of tweaking, I came to this. From System -> Preferences -> Hardware -> Sound

Change all the drop downs to ALSA. Just make sure u “Test” and hear the tone before applying the changes.

pulseaudio with lower cpu usage

Update

I’ve done this yum remove pulseaudio. This removes the root cause 🙂

guitar

Live – Selling the drama guitar tabs

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This entry is part 22 of 42 in the series Guitar

I heard this song recently by Live and found it interesting if it could be played on a Guitar. Here is what I’ve managed.

Tuning: E standard, Capo on 1st fret

// Initial Tab played on 6th or the base E string
E |-6b--6-4-2--|
When u bend on the 6th fret, bend hard a full half note.
And return and play 6th fret again with 4 and 2 in quick succession.

And to love: a god
C              F
And to fear: a flame
C              F
And to burn a crowd that a name
Dm             F           C

And to right or wrong
C               F
And to meek or strong
C              F
It is known, just screem it from the wall
Dm                  F                C

Ive willed, Ive walked, Ive read
C               F           C
Ive talked, I know, I know,
    F       C       C
Ive been here before
C             G