[omniORB] Py_ServantLocator Core Dump

[Gary Pennington]

Duncan Grisby wrote:

> On Friday 15 September, Gary Pennington wrote:
>
> > I have some code which implements the Evictor pattern using Servant
> > Locators (lifted from Henning/Vinoski and adapted to Python). The
> > application is multi-threaded and I am using multiple POA and
> > POAManagers to try and optimize throughput on SMP boxes.
>
> It doesn't have anything to do with your core dump, but do you realise
> that Python has a global interpreter lock?  Only one thread can be
> executing Python code at a time -- every few bytecode instructions,
> the interpreter lock is unlocked to switch to a different thread. This
> means that when your server is running Python code, only one processor
> will be running at a time. Other processors will still be able to do
> other omniORB tasks, like the early stages of operation dispatch, so
> you will still get some advantages from the multiple processors.

I was aware of the Python global lock. I implemented as I did for two
reasons :-

1. Maybe in the future this limitation will be removed and my code will
still be around and will be "ready to go".
2. Large parts of the processing are outside of Python, and they can be
multi-threaded (as you describe above.)

>
>
> > When the system is under heavy load, i.e. load testing, I get a core
> > dump in the server process. The core indicates that the problem arises
> > in :-
> >
> > -----------------  lwp# 12 / thread# 162  --------------------
> >  ff0afa5c
> > __0fRPy_ServantLocatorKpostinvokeRC65OPortableServerIObjectIdP65OPorta
> > bleServerDPOAPCcPvP65OPortableServerLServantBase (36a930, fe00fa3c,
> > 33fbe0, fe00
> > fbe4, a087c, 4ba610) + 40
>
> I don't know what's going on here. There is very little code in
> Py_ServantLocator::postinvoke() which isn't calls into other
> functions. If anything was invalid, I would expect it to coredump in
> some sub-function. Can you build a version of omniORBpy with debugging
> information so we can see exactly where the error happens?

I tried, I can't get omniORB to compile on my system. I need to spend more
time investigating this and will try to put together a debug build next
week so that I can investigate it thoroughly.

Gary


>
>
> Cheers,
>
> Duncan.
>
> --
>  -- Duncan Grisby  \  Research Engineer  --
>   -- AT&T Laboratories Cambridge          --
>    -- http://www.uk.research.att.com/~dpg1 --