[CWB] Performance of "expand to"

[Eros Zanchetta]

Hi Stefan!

On 02/13/2012 12:23 PM, Stefan Evert wrote:
> The "expand to" part should be very fast, unless you're doing this on 
> an s-attribute with a huge number of regions. It's probably the query 
> itself that is slow -- have you tried it without the expand? 

Yes, I tried these queries:

A="paraphernalia";
A="paraphernalia" expand to text;
A="paraphernalia" ::match.text_id="CM8" expand to text;

and they are all instantaneous, the problem appears when I try to 
display the results:

cat A

top shows CQP taking up 100% CPU time, while memory usage is negligible 
(1.4% on a 8 GB machine and plenty of free memory, so I don't think it's 
swapping to disk). I actually timed the query this time: it took 27.5 
seconds on my fastest server.

Doing "cat A" twice in a row doesn't help either (I assumed CQP might 
have cached the results or something, but no, it always takes the same 
time even the second time).

I'm running the latest version of cqp (I checked it out yesterday from 
svn before writing to the list).

I get the same behaviour on two different machines running  Ubuntu 10.04 
(one runs a 64 bit kernel, the other a 32 bit kernel).

I tried it on my Mac too (running Lion), but I get a segmentation fault 
when I try that query (it happened on Ubuntu too before I updated to the 
latest version). I tried to install the latest version of CQP on my Mac 
too, but I couldn't get it to compile so I gave up and moved to a 
different machine.

BTW: in case you want to try it for yourself, I'm using 
mrscoulter.sslmit.unibo.it (you still have an account there).

Cheers,
Eros