Re: Thread-safety "guidelines" of LTDL

[Bob Friesenhahn]

On Wed, 11 Aug 2010, Andreas Mohr wrote:

> Hello,
>
> I've been reading "Using libltdl in a multi threaded environment" at
> http://www.gnu.org/software/libtool/manual/html_node/Thread-Safety-in-libltdl.html#Thread-Safety-in-libltdl
>
> and I must say I feel that it's rather misguided.
>
> I'm as threading-resistant as anyone *)
> , but IMHO suggesting the use of ugly, contention-hampered,
> __insufficient__ mutexes to make LTDL "thread-safe" in an external manner
> is too short-sighted.

Assuming that we agree with most of your points, would it not be 
sufficient to implement libltdl as a singleton model where each "user" 
requests a handle, and accesses via this handle access a single actual 
instance of libltdl in a thread-safe (i.e. mutex protected) way? 
This approach seems to avoid needing to radically modify libltdl. 
This approach should also not hinder performance much since dlopen(), 
dlsym(), and friends already need to include locking in order to be 
thread safe.

As for myself, I am not at all "threading-resistant" and have yet to 
see the horrors occur which were forecast by others when I first 
started to use threading in 1996.  There is no doubt that such horrors 
are possible absent proper design.

Bob
--
Bob Friesenhahn
address@hidden, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/