1d_hydro example does't work

[arturas-venskus-flf]

Hello,

1d_hydro example throws an exception:

terminate called after throwing an instance of 'boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<hpx::exception> >'
   what(): The calling thread does not own the mutex: HPX(lock_error)

OS: Ubuntu 16.04.1 LTS
GCC: 6.2.0
HPX: 1.0.0 compiled with -std=c++14
boost: 1.61
hwloc: 1.11.7

Best,
Arturas

[hkaiser]

@zbyerly Would you mind having a look what's wrong with your example?

[arturas-venskus-flf]

HPX was built using default configuration with c++14 flag enabled. Prior to failure it prints:
nt = 10
nx = 5
n_predict = 10
terminate message ...

call stack:
hpx::lcos::local::mutex::unlock mutex.cpp:95
std::lock_guardhpx::lcos::local::mutex::~lock_guard std_mutex:168
timestep_size 1d_hydro_upwind.cpp:243
hpx_main 1d_hydro_upwind.cpp:676

Do you need additional information?

Best,
Arturas

[arturas-venskus-flf]

program invoked in terminal: ./1d_hydro_upwind
No any parameters are specified explicitly or implicitly
PC has 8 cpu cores

[zbyerly]

yes, I will look.

…

-Zach Byerly

[zbyerly]

can you try using
-Ihpx.stacks.use_guard_pages=0
?

[arturas-venskus-flf]

"./1d_hydro -Ihpx.stacks.use_guard_pages=0" terminates with the same error stating that calling thread does not own the mutex

[zbyerly]

Arturas,
I've been able to reproduce the error. I will get to work fixing it.
If you'd like to communicate more directly, please email me. My email is my github username @gmail.com

[hkaiser]

@arturas-venskus-flf Sorry it took me so long to respond to this, too many things are going on, currently. I can 100% reproduce the issue you reported but I'm not sure yet what's causing this. I'm certain that this is caused by a problem in the example itself, though. I'm inclined to remove the example as a possible resolution as it is most likely broken and does not demonstrate any facilities or ideas not shown elsewhere.

Is this example of particular value for you? Or did you just run across the problem and decided to report it?

[arturas-venskus-flf]

@hkaiser Yes, this example is particularly interesting for my company because our main simulation tool does hydro simulations and we are evaluating hpx as a way to do distributed computations. So easiest and fastest way is just use provided hydro example and play with it. But we can continue without this example.

As a side note I would like to see much more similar examples that demonstrate how to solve particular pde's using hpx. For hpx novice user, especially for scientist/physicist who are not software engineers, initially is not enough to learn only basic concepts, facilities and ideas, but is very valuable to see examples showing how to compose those concepts to solve practical problems. One of the motivation to try hpx was existence of stencil and hydro codes examples showing that hpx targeting heavy number crunching problems. Off course good scalability properties are expected from such examples.

[hkaiser]

@arturas-venskus-flf understood. I still would like to remove this example as it is very old (and broken).

For better examples demonstrating how to orchestrate distributed parallelism with HPX I'd suggest you look at the 1d_stencil series of examples or the 2d stencil examples accompanying the tutorial slides here. The 2d stencil examples are especially useful as they demonstrate how to use channels to organize the communication fully overlapped with the computation.

Also, please feel free to ask questions either on IRC (#ste||ar on freenode) or the mailing list (hpx-users@cct.lsu.edu). We'd be more than happy to help with what you're trying to do.