[OpenSER-Users] perl + unixODBC

[Bastian Friedrich]

Hi,

sorry for not replying any earlier; I'm currently on my holidays and 
(yet) have a very limited time for computer stuff :)

Your evaluation probably already pointed out the problems you 
experience. Your backtrace shows that the segfault occurs during the 
code in ODBC.so.

On Montag 24 September 2007, Murilo Lacerda Yoshida wrote:
>   So first of all a question: does the Perl module uses iThreads?

The OpenSER perl module is linked against the system's perl library -- 
which will in most cases use the POSIX threading model (pthread) as its 
underlying technology.

iThreads -- as far as I understood things -- refers to threading within 
Perl itself, i.e. when you create threads from within Perl. In OpenSER, 
the server itself forks.

The sections in the documentation that you found nonetheless probably 
refer to the problems that you experience.

>   If the perl module really uses iThreads, then what I have to do is
> clear, right? I have to take another path to communicate with my DB,
> as the perl module isn't reliable when it uses DBI in multi threaded
> environments.

... or you need to find a way to communicate without using DBI -- which 
may be quite a problem, anyway.

>   Another path would be to make openser work in only one thread, but
> that will affect the performance of my server.

Probably not an option, if you are stress testing your server?

>   Another question is: If the perl module really uses iThreads, then
> is there another perl extension (like DBI) in which the same problem
> occurs?

Most Perl packages are "Perl only"; I would not expect to occur any 
thread/multi-process related problems in these packages. Packages 
with "XS" components (C libraries, resulting in .so files) are more 
prone to raising problems similar to the one you are experiencing; code 
they contain run in the same address space as the OpenSER server. Due 
to this, they can crash the server and do (more or less) whatever they 
want. Given the number of Perl packages (more than 4000 on cpan.org), 
we cannont evaluate each of them :(

I'm not aware of any other "dangerous" packages, though.

I will add a "warnings" section in the perl module documentation as soon 
as I have time.

Happy scripting,
   Bastian

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