[moin-user] MoinMoin very slow

[Paul Boddie]

On Wednesday 1. November 2017 23.44.28 Volker Wysk wrote:
> 
> This looks like this:
> 
> Page.execute = 20.668s
> i18n_init = 0.299s
> init = 0.370s
> loadLanguage = 0.115s
> load_multi_cfg = 0.274s
> run = 41.985s
> send_page = 41.809s
> send_page_content = 41.156s
> send_page_content|1 = 20.578s
> send_page|1 = 20.578s
> total = 42.354s

So, working through this without any recent knowledge or experience myself, I 
see that the MoinMoin.Page.Page.send_page_content method is the thing using 
all the time. It obtains a parser and then either gets a cached version of the 
page or formats a new version.

Is there anything special about the page? Anything like macros being used, for 
instance.

> > Other than that, some kind of idea of the environment Moin is operating
> > in might be useful...
> 
> Kubuntu 16.04, Apache2, ...
> 
> > Publicly accessible or inaccessible?
> 
> inaccessible, one user only
> 
> > Lots of processes on the machine or only a few?
> 
> This process runs alle the time with 100% CPU:
> 
>   PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND
>  8509 www-data  20   0  106144  49460   9340 R 100.0  0.6   0:04.94 python

This indicates that it is presumably quite busy and not necessarily waiting 
for input/output, so the nameserver suggestion is probably uninteresting.

> > Local or network filesystem?
> 
> Local.
> 
> > Nameserver usage: are the Web server and Moin doing reverse DNS lookups?
> 
> How to find this out?

I suppose the easiest way is to just look at your Apache and Moin logs and see 
if you have numeric IP addresses or ones with actual names. But I doubt that 
this would cause the time to be consumed in send_page_content, so we can 
perhaps rule this out as a cause.

> > Try show_timings first of all, though.
> 
> See above.
> 
> And: It runs much faster for smaller pages.

I do wonder about "send_page_content|1" which might well be a recursive call 
generating a subpage, perhaps for a table of contents. The way that the 
combined time is approximately double the individual times might suggest that 
the cache isn't working properly. But 20s page generation times are not 
exactly normal, either.

It's been a long time since I troubleshooted a Moin performance problem like 
this, and then I think it was probably related to the low-performance, non-
Xapian search function, not page loading.

Paul