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<title>The Slashdot Effect LG #38</title>
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<H4>
"Linux Gazette...<I>making Linux just a little more fun!</I>"
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<H1><font color="maroon">The Slashdot Effect, An Analysis of Three Internet Publications</font></H1>
<H4>By <a href="http://ssadler.phy.bnl.gov/adler/adler">Stephen Adler</a></H4>
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<Blockquote>
<Blockquote>
<center><i>Abstract</i></center>
<br>
Apache httpd log files have been analyzed to show the <i>Slashdot
Effect</i>. This effect is known as the spontaneous high hit rate
upon a web server due to an announcement on a high volume news web
site. Three papers were published on the Internet and announced on the
high volume news web sites of slashdot.org, linuxtoday.org, and
freshmeat.org. The hit rate plots as a function of time are correlated
with the announcement times on these web sites. These correlations
clearly demonstrate the magnitude and significance of the
<i>Slashdot Effect</i>.
<p>
Author's note: Here
is an <a href="./adler2.html">Addendum</a> to this paper
which details the Slashdot effect on this paper.
</blockquote>
</blockquote>
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<p>
Three papers were published on the Internet. One on October 20th, 1998
titled
<a href="http://ssadler.phy.bnl.gov/adler/fiw98/fiw98.html">
<i>Fall Internet World 98, A View From The Show Floor</i></a>,
one on November 14th, 1998 titled
<a href="http://ssadler.phy.bnl.gov/adler/OSS/OSS.html">
<i>Preserving the Information Ecosystem</i></a>,
and one on January 28th, 1999 titled
<a href="http://ssadler.phy.bnl.gov/adler/Stallman/Stallman.html">
<i>An Ode to Richard Stallman</i></a>. Soon
after these papers were published, Slashdot, Linux Today and Freshmeat
ran announcements in one form or other regarding the availability of
these papers. Within less than an hour, the hit rate to the system
hosting these papers surged. This surge in hit rate on the hosting web
server is known as the <i>Slashdot Effect</i>. The magnitude of the
hit surge varied with each posting since not all three web sites
posted the articles at the same time, if at all. What follows is a
brief case study of the <i>SlashDot Effect</i> for each of these
papers.
<p>
<hr width="80%">
<p>
<center>
<a href="./gx/adler/fullTime.jpg"><img src="./gx/adler/fullTimeSmall.jpg"></a>
</center>
<p>
To start, a plot of the hit rate in hits/minute is shown above for the
past 4 months during which the three papers were published on the
Internet. The time on the X axis is that of the Unix system time in
seconds since Jan 1st, 1970 scaled down by a factor of 1000. The width
of one bin of the histogram is show in a text field on the bottom
right of the plot. The first recorded hit was 27/Sep/1998:21:02:08,
and the last recorded hit was 31/Jan/1999:03:59:43. These two dates
set the two limits of the X axis time scale. The Y axis shows the
number of raw hits per minute averaged over the time of one bin
width. (In the case of the plot above, averaged over 902.39 minutes.)
The data is shown in raw hits/minute, since for each paper referenced
by a viewer on the Internet generated several hits. One needs to apply
a scale factor, which is the number of hits generated per paper, in
order to measure the number of readers of these publications. Since
the purpose of this paper is to show the <i>Slashdot Effect</i> and
not to try and measure the number of readers of the papers, this
scaling is not performed.
<p>
Vertical lines are drawn on the above plot to indicate the time of the
posting by the three web sites. The red lines indicate the
announcements by Slashdot, the green lines by Linux Today, and the
blue lines by Freshmeat. From this plot, one can see clear evidence of
the <i>Slashdot Effect</i>. What follows is a closer examination of
each one of these postings, since this full time view of the hit rate
to the server hides some detail of the this effect.
<p>
<hr width="80%">
<p>
<center>
<a href="./gx/adler/fiw98Zoom.jpg"><img src="./gx/adler/fiw98ZoomSmall.jpg"></a>
</center>
<p>
This plot above is a zoom in around the time of the announcement of the
Fall Internet World 98 paper. The paper was first announced around 8am
on the 20th of October and about 30 minutes later, the hit rate to the
server surged to well over a 100 hits/minute. This was when the author
first experienced the <i>Slashdot Effect</i>. Soon after, around 1pm
of the same day, Linux Today announced the article. One can see a
slight resurgence in the hit rate about 30 minutes after the Linux
Today announcement.
<p>
<hr width="80%">
<p>
<center>
<a href="./gx/adler/ossFull.jpg"><img src="./gx/adler/ossFullSmall.jpg"></a>
</center>
<p>
The plot above shows the hit rate to the same server during the time
that "Preserving the Information Ecosystem" was published and
announced on Linux Today and posted as a Freshmeat editorial. Linux
Today announced it on November 14th, and the Freshmeat editorial was
posted on Nov 21th. The announcement of this article on Linux Today
was only visible for about 12 hours on its front web page, where as
the article was visible on the front page of the Freshmeat web site
for several days. This is an indication as to why the Freshmeat
announcement generated more hits than that of the Linux Today
announcement.
<p>
<hr width="80%">
<p>
<center>
<a href="./gx/adler/rmsMoreZoom.jpg"><img src="./gx/adler/rmsMoreZoomSmall.jpg"></a>
</center>
<p>
The final plot above shows the <i>Slashdot Effect</i> with respect to
the last paper titled "An Ode to Richard Stallman". While the paper
was being written, notification of its existence was sent to members
of the LXNY group and to the general redhat mailing list. Therefore
the activity to the server started to increase before the Linux news
web sites announced this article. On Jan 28th, around 1pm, Linux Today
announced the article and published a text only version on their web site.
Slashdot followed with an announcement of the article and a hyper link
to the article at around 4pm. One can see the very impressive surge
in hits after the Slashdot announcement in which the hit rate went
from about 30 hits/minute up to over 250 hits/minute in about a 15
minute period.
<p>
<hr width="80%">
<p>
In conclusion, the term <i>Slashdot Effect</i> has been referenced
many times on sites around the Internet. With the publication of
articles related to Linux and the Open Source movement, and the
announcement of these articles to Linux related news web sites, one
has a chance of documenting, in a controlled environment, this
effect. The plots of the hit rate received by the hosting server
clearly shows the existence of the <i>Slashdot Effect</i>. This effect
varies in magnitude for different reasons. One reason being the
interest of the readership in the content of the article being
announced. Another reason being the form in which the article is
announced. For example, the article titled "an Ode to Richard
Stallman" was announced by Slashdot and Linux Today. Linux Today
published the text of the article on their own web site, thus keeping
many of the hits, by readers interested in this article, on their
server. This strongly dampens the surge in hit rate to the system
hosting the full article. On the other hand, Slashdot announced the
article via a hyper link to the server hosting the full article and
thus the local host received all the hits from Slashdot readers. The
purpose of this article is just to document the existence of the
<i>Slashdot Effect</i> and not to try and gauge which news web site
has the predominant reader-ship.
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<center><H5>Copyright &copy; 1999, Stephen Adler <BR>
Published in Issue 38 of <i>Linux Gazette</i>, March 1999</H5></center>
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