[pmwiki-devel] Internal server error message

[Petko Yotov]

On 08.10.2014 22:22, Randy Brown wrote:
> This may also have something to do with my host: I see from Top that
> on my shared server at the moment virtual memory is 12300528k total,
> 12000484k used, yet my own processes in the list show zero CPU or
> memory.

On a shared server this is not unusual. It is unusual that one 
pmwiki.php process requires 100% of the CPU resources for a long time.

> Regardless of my woes, I didn't know about some of the limitations you
> mentioned. That's important information. Perhaps those limitations are
> all documented, but of the list you mentioned, I only recall seeing
> the one about avoiding PTVs that are based on other PTVs. I didn't
> know there were issues with PTVs using markup expressions and
> conditionals. Is there a good page to document such limitations?

Embedded PTVs in other PTVs should not get captured into infinite loops 
since version 2.2.3 (2009-07-16).

The mecanism of PTVs is probably not very intuitive. When you place 
{OtherPage$:Variable} in a page, it is exactly like if you had "copied" 
the wikitext value of the variable and "pasted" it into the current 
page. So, markup expressions and conditionals will be processed and 
evaluated at a later point from the "pasted" content and what surrounds 
it. For example, you cannot paste a PTV containing a markup expression 
inside a markup expression, as this will produce incorrect wikitext. If 
the PTV contains a nested conditional and you paste it inside a 
conditional, the parent conditional should have a different index number 
like (:if2:), or the conditionals will break not like you expect.

Anyways, these can produce errors in the processing, but shouldn't 
require 100% CPU and RAM usage. An incorrect nested pagelist template 
might. You can disable pagelists by adding this to config.php:

    $EnablePageList = 0;

then test the wiki for errors.

Another thing to check: the Notify feature, depending on the server 
configuration, might bring up the CPU usage. Once again, this shouldn't 
cause crashes, but who knows.

Petko