[Koha] Slow Koha OPAC login process

[Michael Kuhn]

Hi

We're running a productive host with Debian GNU/Linux 8 and Koha 16.11.04.

One month ago I already described the case that on this host the Koha 
OPAC login process is often very slow. At such occasions the following 
process can be seen with "top", taking 99% of the CPU resources:

phsh-ko+ 59422 56031 11 16:30 ? 00:00:35 
/usr/share/koha/opac/cgi-bin/opac/opac-user.pl

Nothing is written to the file "opac-error.log".

I had already sent the output of strace in my e-mail from 18 April 2017 
18:09 but this didn't help no further. See 
https://lists.katipo.co.nz/public/koha/2017-April/047804.html

With my poor Perl knowledge I have now measured the execution time of 
the various parts of script "opac-user.pl". As I found out everything is 
always very fast (using less than 1 second execution time) except the 
very last function in this script which looks as follows:

output_with_http_headers $cgi, $cookie, $template->output, $content_type;

Usually this function takes around 2 seconds to complete, but in the 
case of the slow login process it takes around 32 seconds which makes me 
think there must be some kind of timeout (30 seconds).

I tried to find out more but I am stuck in file 
"/usr/share/koha/lib/C4/Output.pm" where function 
"output_html_with_http_headers" makes use of another function called 
"output_with_http_headers".

Can anyone please give me a hint how I could dig deeper to maybe find 
out why the script "opac-user.pl" sometimes takes so long to complete 
its task?

Best wishes: Michael
-- 
Geschäftsführer · Diplombibliothekar BBS, Informatiker eidg. Fachausweis
Admin Kuhn GmbH · Pappelstrasse 20 · 4123 Allschwil · Schweiz
T 0041 (0)61 261 55 61 · E mik at adminkuhn.ch · W www.adminkuhn.ch