> Ran into an issue where an HPX action that I've been executing under
> hpx::parallel::transform (in lieu of hpx::parallel::for_each) hangs on the
> hpx::finalize() call. Are there any troubleshooting or debugging
> techniques that could be used to figure out how to resolve this issue? I'm
> using 1.0.0.
> static void run(const size_t idx) {
> hpx::cout << idx << hpx::endl;
> }
> HPX_PLAIN_ACTION(run, run_action);
> int hpx_main(int argc, char **argv) {
> std::vector<size_t> idx_list;
> // fill idx_list with numbers to print ...
>
> std::vector< hpx::future<void> > futures;
> futures.reserve(idx_list.size());
> hpx::parallel::transform(
> hpx::parallel::par,
> std::begin(idx_list),
> std::end(idx_list),
> [&localities, &distarr] (idx) {
> auto loc = localities[distarr.get_partition(idx)];
> return hpx::async<run_action>(loc, idx);
> });
> hpx::wait_all(futures);
> // printing debug statements after the hpx::wait_all demonstrate the
> hpx::wait_all has completed successfully
>
> hpx::finalize();
>
> }
>From what I can see you actually never store the futures returned from
>async<run_action>() in to the 'futures' vector.
Also, I'm surprised this code even compiles as the lambda returns a
future<void> which transform will attempt to assign to the current element
(which is a size_t).
I'd assume the actual code you're running looks like:
int hpx_main(int argc, char **argv) {
std::vector<size_t> idx_list;
// fill idx_list with numbers to print ...
std::vector< hpx::future<void> > futures;
futures.reserve(idx_list.size());
hpx::parallel::transform(
hpx::parallel::par,
std::begin(idx_list),
std::end(idx_list),
std::begin(futures), // <-- is this missing above?
[&localities, &distarr] (idx) {
auto loc = localities[distarr.get_partition(idx)];
return hpx::async<run_action>(loc, idx);
});
hpx::wait_all(futures);
return hpx::finalize();
}
In which case I wouldn't see any problems with the code :/ Can you show me the
full code, please (feel free to send it to me privately, if you don't want to
share it on the list).
Hold on - there is an idea. We just fixed a shutdown problem (hang) which was
occurring under certain circumstances (see
https://github.com/STEllAR-GROUP/hpx/commit/ab353f656a08f3426224b4e86fa9715a52afd8ec),
that was about 10 days ago. What version of HPX do you use?
Regards Hartmut
---------------
http://boost-spirit.com
http://stellar.cct.lsu.edu
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