Steve,
> Going back to the channels discussion, how do you know if a channel has
> been already registered or not?
>
> Look at the following code below (running with 2 localities):
> - they create or connect to the same channel name
> - if I introduce a delay in the receiver locality I get the following
> error:
>
> Assertion failed: (buffer_map_.empty()), function ~receive_buffer,
> file hpx_install/include/hpx/lcos/local/receive_buffer.hpp, line 101.
I think I understand what is going on. This assert says that you're trying to
destroy a channel with data sitting in the pipeline. This is caused by your
code:
{
hpx::lcos::channel<int> c(hpx::find_here());
c.register_as(“name");
c.set(3);
}
Which makes the channel go out of scope before the other locality had a chance
to connect and to extract the value.
There is also a deeper problem lurking behind the scenes, but that's something
I need to think about more before doing anything about it.
Regards Hartmut
---------------
http://boost-spirit.com
http://stellar.cct.lsu.edu
>
> Here is the sample code:
> —————————
>
>
> void spmd_int(DataFlow::ShardId cid){
> if(cid%2==0){
> hpx::lcos::channel<int> c(hpx::find_here());
> c.register_as(“name");
> c.set(3);
> }
> else{
> usleep(1000000); // delay
> hpx::lcos::channel<int> c;
> c.connect_to("name");
> hpx::future<int> p = c.get();
> p.get();
> }
> }
>
>
> int hpx_main(boost::program_options::variables_map& vm){
> std::vector<hpx::naming::id_type> localities =
> hpx::find_all_localities();
>
> int loc_count = 0;
> for(auto loc: localities){
>
> spmd_int_action act;
> hpx::async(act, loc, loc_count);
>
> loc_count++;
> }
> }
>
> —————————
>
>
> What is happening here?
> If I add a
> c.connect_to("name");
>
> to the the same task that does the registration (after
> c.register_as(“name");) it works, but I don’t like it (and in my actual
> application I still get this error).
>
> More in general, when you have many of this channels at scale, do you
> think is better to use a register_as/connect_to mechanism or to pass alle
> the necessary channels to each locality at the beginning when I do the
> initial SPMD spawn?
>
> Thanks,
> Steve
>
>
> On 11 Oct 2017, at 14:53, Steve Petruzza <spetru...@sci.utah.edu> wrote:
>
> Thanks Hartmut, it all makes sense now.
>
>
>
> On 11 Oct 2017, at 14:51, Hartmut Kaiser <hartmut.kai...@gmail.com> wrote:
>
>
>
> I think I’ve found a workaround.
>
> If I use a typedef as following:
>
> typedef std::vector<char> vec_char;
>
> HPX_REGISTER_CHANNEL(vec_char);
>
> It works, but if I try to use directly:
> HPX_REGISTER_CHANNEL(std::vector<char>)
>
> this gives me the error I reported before.
> The issue might be in the expansion of the macro HPX_REGISTER_CHANNEL.
>
> Yes, that confirms my suspicion. I will have a looks what's going on.
>
> Doh! The problem is that the (literal) parameter you give to the macro has
> to conform to the rules of a valid symbol name, i.e. no special characters
> are allowed (no '<', '>', etc.). Sorry, this has to be documented properly
> somewhere, and I forgot to mention it in the first place.
>
> The 'workaround' you propose is the only way to circumvent problems. There
> is nothing we can do about it.
>
> Also, wrt your comment that everything is working if you use
> hpx::lcos::local::channel instead - this is not surprising. The local
> channel type is representing a channel which can be used inside a given
> locality only (no remote operation, just inter-thread/inter-task
> communication), hence its name. Those channels don't require the use of
> the ugly macros, thus there is no problem.
>
> HTH
> Regards Hartmut
> ---------------
> http://boost-spirit.com
> http://stellar.cct.lsu.edu
>
>
>
>
> Thanks!
> Regards Hartmut
> ---------------
> http://boost-spirit.com
> http://stellar.cct.lsu.edu
>
>
>
>
> Steve
>
>
>
>
> On 10 Oct 2017, at 18:38, Steve Petruzza <spetru...@sci.utah.edu> wrote:
>
> Sorry, regarding the version that I am using it is the commit of your
> split_future for vector:
>
> Adding split_future for std::vector
>
> - this fixes #2940
>
> commit 8ecf8197f9fc9d1cd45a7f9ee61a7be07ba26f46
>
> Steve
>
>
>
> On 10 Oct 2017, at 18:33, Steve Petruzza <spetru...@sci.utah.edu> wrote:
>
> hpx::find_here()
>
>
_______________________________________________
hpx-users mailing list
hpx-users@stellar.cct.lsu.edu
https://mail.cct.lsu.edu/mailman/listinfo/hpx-users
