Re: [igraph] Multi-threading and igraph

[Thomas Gorochowski]

Ah yes, sorry about that! Here is the link but it is very brief and only 
outlines the basics:

http://www.chm.tu-dresden.de/edv/manuals/aix/aixprggd/genprogc/writing_reentrant_thread_safe_code.htm

I've had a look at the tread-local storage and agree that a more portable 
solution would better if possible.

If I pul up anything further I will let you know,

Tom

On 30 Oct 2010, at 08:32, Gábor Csárdi <address@hidden> wrote:

> Thanks Tom, but I think you forgot the web page.
> 
> Actually, as a solution, I was thinking about assigning a context to
> each thread, and this would store the thread-local data. Then at the
> beginning of a thread you would need to call an extra function to
> allocate this context, but maybe this is not a big deal.
> 
> Locking does not really work, at least it is not that simple, because
> the threads really need different copies of the error objects, at
> least if we don't want one thread failure break the whole program.
> 
> So either the context, or the thread-local variables that Tamas
> mentioned, would work. I don't like the gcc-specific aspect of the
> thread-local thing, but maybe there is a portable solution as well.
> 
> Best,
> Gabor
> 
> On Sat, Oct 30, 2010 at 12:39 AM, Thomas Gorochowski
> <address@hidden> wrote:
>> Hi Gabor,
>> 
>> The following webpage outlines the main points you would need to consider. 
>> I'm not familiar with how errors are handled in igraph but one work around 
>> if static variables crop up is to use locks to ensure that changes become 
>> atomic and therefore safe.
>> 
>> I'm not am expert, but will ask some of the developers in our group to see 
>> if they have any other suggestions.
>> 
>> All the best,
>> 
>> Tom
>> 
>> On 29 Oct 2010, at 22:03, Gábor Csárdi <address@hidden> wrote:
>> 
>>> Hi Tom,
>>> 
>>> indeed, the error handling is not thread-safe in igraph. I guess it
>>> would not be too hard to make it thread-safe, but I am not an expert
>>> on this. Could you recommend some good documentation on writing
>>> thread-safe libraries?
>>> 
>>> Thanks,
>>> Gabor
>>> 
>>> If On Fri, Oct 29, 2010 at 10:22 PM, Thomas Gorochowski
>>> <address@hidden> wrote:
>>>> Hi there,
>>>> 
>>>> I am attempting to use OpenMP for some statistical sampling. When using 
>>>> igraph functions within a parallel block I have noticed errors occur such 
>>>> as the following:
>>>> 
>>>> corrupt finally stack, popping 2 elements when only 1 left
>>>> Assertion failed: (no>=0), function IGRAPH_FINALLY_REAL, file error.c, 
>>>> line 126.
>>>> Abort trap
>>>> 
>>>> I'm assuming that igraph has not been written with multi-threading in 
>>>> mind, however, was wondering if there are any plans to make the library 
>>>> thread-safe in the near future? I'd ideally not like to fork processes as 
>>>> some data is required to be shared and passing that via messages is never 
>>>> much fun!
>>>> 
>>>> Thank for a great library and keep up the good work.
>>>> 
>>>> Tom.
>>>> 
>>>> --
>>>> T.E. Gorochowski
>>>> University of Bristol, Centre for Complexity Sciences (BCCS)
>>>> http://www.chofski.co.uk, address@hidden
>>>> 
>>>> Try our dynamical network simulator at http://www.netevo.org
>>>> 
>>>> 
>>>> _______________________________________________
>>>> igraph-help mailing list
>>>> address@hidden
>>>> http://lists.nongnu.org/mailman/listinfo/igraph-help
>>>> 
>>> 
>>> 
>>> 
>>> --
>>> Gabor Csardi <address@hidden>     UNIL DGM
>>> 
>>> _______________________________________________
>>> igraph-help mailing list
>>> address@hidden
>>> http://lists.nongnu.org/mailman/listinfo/igraph-help
>> 
>> _______________________________________________
>> igraph-help mailing list
>> address@hidden
>> http://lists.nongnu.org/mailman/listinfo/igraph-help
>> 
> 
> 
> 
> -- 
> Gabor Csardi <address@hidden>     UNIL DGM
> 
> _______________________________________________
> igraph-help mailing list
> address@hidden
> http://lists.nongnu.org/mailman/listinfo/igraph-help