[WikiEN-l] Re: How Wikipedia behaves under heavy load

[Daniel P.B.Smith]

My personal observations/superstitions, which are NOT based on any 
technical insight. My mental model is that different Wikipedia 
operations require different capabilities, and perhaps in some cases 
different servers, and therefore degrade differently on heavy load.

a) For some reason, reloading a page after saving an edit is one of the 
LEAST reliable operations and quickly degrades under load. The failure 
can take three different forms. The most common is that the browser 
times out. Lately, a very common one has been an error message saying 
the database is not available. A third form is that the supposedly 
edited page was reloaded, but shows the original text rather than the 
edited text.

In ALL THREE cases, there's much better than a 50% chance that the edit 
actually took place.

In ALL THREE cases, the most sensible thing to do is save the edited 
Wiki-marked-up text of the whole article somewhere locally, wait about 
five minutes, then try to view the page and see whether the edit took.

b) A very common symptom under heavy load is that actions "take," but 
do not become "visible" for many minutes. For example, when preferences 
change spontaneously (an infuriating thing which hits me about every 
two weeks) and I change them back, my changes USUALLY take effect--but 
do not become visible for many minutes afterwards. Until I discovered 
this, I was utterly baffled because I would keep trying various things 
to "fix" the problem, every possible combination of clearing caches I 
could think of and when the changes took several minutes later I had 
tried several other things and naturally assumed that it was the last 
thing I'd tried, rather than the first.

c) For reasons that baffle me, the "Go" button creates some kind of 
search string and does some kind of search. Under heavy load, all 
search operations degrade. This means that manually typing

http://en.wikipedia.org/wiki/Foobar

is much more reliable in retrieving the Foobar article than typing 
"Foobar" into the search box and pressing "Go."

When things are slow, I usually copy the http://en.wikipedia.org/wiki/ 
text out of the address box for handy pasting in later.

d) I am trying to learn to welcome the slowdowns as nature's way of 
reminding me that I'm spending way too much time on Wikipedia. Of 
course, the most infuriating situations are the ones when I MEAN to say 
"this article should definitely not be," press SAVE, see that I 
accidentally typed "this article should definitely be", press EDIT, fix 
it, and get a database error. In these situations, I console myself 
with the thought that nobody really cares that much about my opinion.

--
Daniel P. B. Smith, dpbsmith at verizon.net
"Elinor Goulding Smith's Great Big Messy Book" is now back in print!
Sample chapter at http://world.std.com/~dpbsmith/messy.html
Buy it at http://www.amazon.com/exec/obidos/ASIN/1403314063/