On Thu, Jan 21, 2016 at 11:10:47AM -0600, Hartmut Kaiser wrote: > Jan, > > > I'm still working on my parallel rendering project and can't find a > > solution for an error for over a month now. > > Whenever i call my rendering routine through an action (component- or > > plain action), i get a Segfault at glLinkProgram(). > > If i call it in hpx_main() as a normal method or through std::async, it > > works fine, so my method is not faulty (correct image, no glErrors). > > > > I want to call it in a component action to render 16 images on 16 > > components of a 16-core node/locality simultaneously, but the simplified > > version of just calling it once on a 1-core locality in a plain action > > in the hpx_main() gives the same segmentation fault. > > > > I know this most likely is an error on the interaction of OpenGL and > > asynchronous actions in general, but maybe someone on this list has an > > idea or has used OpenGL with HPX. > > Is OpenGL thread-safe in the first place? If you run an OpenGL function from > inside an action and use more than one core, you might end up calling into > OpenGL concurrently, not sure if that's a problem.
OpenGL contexts may be made current on any OS thread, but a given context may only be current on a single OS thread at a time. As HPX actions may be dispatched on different OS threads over time, you need to be very careful about which OS thread your context is current on. In general when doing concurrency and 3D APIs, you tend to prepare as much work as possible in threads without invoking API functions, and chew through the deferred work in a dedicated OS thread that has control over the context. While there's shared contexts and shared resources in OpenGL, they have a bit of a performance penalty and are not quite the fastpath when it comes to driver implementations. Some resources like FBOs and VAOs cannot be shared at all. > Another issue could be that you run out of stack-space. HPX threads have a > very limited stack-size by default which is easily overflown. Try running > your app with -Ihpx.stacks.small_size=0x20000 to increase the default > stack-sizes used. -- Lars Viklund | [email protected] _______________________________________________ hpx-users mailing list [email protected] https://mail.cct.lsu.edu/mailman/listinfo/hpx-users
