On Wed, Apr 16, 2014 at 2:16 AM, Guido Tack <t...@gecode.org> wrote: > Hi Andrea, > > two things you could try: > 1) if backup is a global variable, you need to protect it with a mutex, > since clone is not thread-safe. > 2) you're using the clones you create in different threads, so you should > pass "false" to clone instead of "true" (that way the clone is really > independent of backup and doesn't share any data structures with it) >
Hi, it works perfectly! Thank you, Andrea > > Cheers, > Guido > > On 16 Apr 2014, at 1:07 am, Andrea Peano <andrea.pe...@unife.it> wrote: > > Thanks for your reply. > > I tried to simplify my real architecture, maybe too much! > > I create a "backup" space before starting the search, that is a copy of > the original space used during the search, and it is a global variable of > the code. > > Within the ::post function I create a copy of the backup model, I update > this space by passing the current (partial) solution, and then I search the > first sol, like that: > MyModel *inner_model=static_cast<MyModel *>(backup->clone(true)); > inner_model->update_variables(this->partial_sol_values()); > inner_model->status(); > ... > inner_dfs.next(); > > Scary stuff again, I guess! > > In general, I need of a partial solution before starting the second step > in order to run some scary heuristics :) > > You refer to this discussion: > http://www.gecode.org/pipermail/users/2013-January/003769.html > don't you? > > Thanks, > Andrea > > > On Tue, Apr 15, 2014 at 4:27 PM, Christian Schulte <cschu...@kth.se>wrote: > >> Hi Andrea, >> >> >> >> Whoa! Scary stuff ;-) That's not possible to clone a space that is >> currently in use for propagation (because that is what is still going on >> when the ::post function is executed). >> >> >> >> However it should work much much easier: there has been a discussion in >> this users group a while ago on how to split search into two parts. Then >> you can parallelize each one. Just go through the archive (or maybe one of >> the users who took part in the discussion can help here). >> >> >> >> Cheers >> >> Christian >> >> >> >> -- >> >> Christian Schulte, Professor of Computer Science, KTH, >> www.ict.kth.se/~cschulte/ >> >> >> >> *From:* users-boun...@gecode.org [mailto:users-boun...@gecode.org] *On >> Behalf Of *Andrea Peano >> *Sent:* Tuesday, April 15, 2014 2:35 PM >> *To:* users@gecode.org >> *Subject:* [gecode-users] Multithreading executions crash >> >> >> >> Hello everyone, >> >> my model is solved by a two-steps search. The first step can be a DFS as >> well as a BAB search, the second step is always a DFS. >> >> >> >> I implemented this search by following the section "Executing code >> between branchers" of the Gecode's guide, like this: >> >> branch(*this, MyModel::post) >> >> >> >> The function "post" copies the current space into a local variable, then >> instantiates a new DFS engine and finally calls the method "next", in order >> to compute only the first solution. >> >> >> >> MyModel *inner_model=static_cast<MyModel *>(this->clone(true)); >> >> inner_model->status(); >> >> ... >> >> inner_dfs.next(); >> >> >> >> The idea is to parallelize the first level of the search... but if I use >> only one thread everything works fine, otherwise every time the execution >> crashes on a different instruction of the function "post". >> >> >> >> Do you have any clue about this behavior? >> >> The worst scenario I see is that this solving architecture is totally >> incompatible with the multithreading system implemented in Gecode. >> >> >> >> Thanks, >> >> Andrea >> > > > > -- > > Andrea Peano - PhD student > Department of Engineering - University of Ferrara > Tel: +39 0532 97 4827 > _______________________________________________ > Gecode users mailing list > users@gecode.org > https://www.gecode.org/mailman/listinfo/gecode-users > > > -- Andrea Peano - PhD student Department of Engineering - University of Ferrara Tel: +39 0532 97 4827
_______________________________________________ Gecode users mailing list users@gecode.org https://www.gecode.org/mailman/listinfo/gecode-users
