Re: [Help-glpk] Thread-safety

[François Galea]

Andrew Makhorin a écrit :
> > What I need is indeed reentrability : what I want to do is solve
> > different subproblems of the same problem in parallel, so each LPX is 
> > local to one thread only.
>
> This must work.

In fact, I forgot to mention one crucial thing : even though each LPX is 
handled by only one thread, it happens that one LPX is solved, then 
destroyed by a thread which is different from the thread which generated 
the LPX. Hence a bunch of funny error messages from ufree.

> > I think it should be possible to implement an GNU/Linux equivalent
> > for your TLS-based routines, using the pthread_setspecific family of
> > routines of the POSIX threads library. I can have a look at it, if
> > you like.
>
> If you are using posix pthreads, writing that two routines must be
> easy to you; see w32 version and examples/mtsamp.c as an example.
> I did not include the posix version in the distribution because of its
> incompatibility with GNU/Linux.

I did implement a posix threads version of your TLS-based version, but 
it didn't solve the ufree errors.

Actually, I solved my problem by recompiling GLPK with the GLP_HUGE_MEM 
constant defined, so that umalloc/ufree are just compiled as wrappers 
for malloc/free, which are reentrant and allow exchange of malloced 
blocks between threads.

regards,

François