Man Linux: Main Page and Category List


       multithreading_support - Multithreading Support in Coin The support in
       Coin for using multiple threads in application programs and the Coin
       library itself, consists of two main features:

       · Coin provides platform-independent thread-handling abstraction
         classes. These are classes that the application programmer can freely
         use in her application code to start new threads, control their
         execution, work with mutexes and do other tasks related to handling
         multiple threads.
       The classes in question are SbThread, SbMutex, SbStorage, SbBarrier,
       SbCondVar, SbFifo, SbThreadAutoLock, SbRWMutex, and SbTypedStorage. See
       their respective documentation for the detailed information.
       The classes fully hides the system-specific implementation, which is
       either done on top of native Win32 (if on Microsoft Windows), or over
       POSIX threads (on UNIX and UNIX-like systems).

       · The other aspect of our multi-threading support is that Coin can be
         specially configured so that rendering traversals of the scene graph
         are done in a thread-safe manner. This means e.g. that it is possible
         to have Coin render the scene in parallel on multiple CPUs for
         multiple rendering pipes, to better take advantage of such high-end
         systems (like CAVE environments, for instance).
       Thread-safe render traversals are off by default, because there is a
       small overhead involved which would make rendering (very) slightly
       slower on single-threaded invocations.
       To get a Coin library built with thread-safe rendering, one must
       actively re-configure Coin and build a special, local version. For
       configure-based builds (UNIX and UNIX-like systems, or with Cygwin on
       Microsoft Windows) this is done with the option ’--enable-threadsafe’
       to Autoconf configure. For how to change the configuration and re-build
       with Visual Studio, get in touch with us at ’’.

       There are some restrictions and other issues which it is important to
       be aware of:
       · We do not yet provide any support for binding the multi-threaded
         rendering support into the SoQt / SoWin / etc GUI bindings, and
         neither do we provide bindings against any specific library that
         handles multi-pipe rendering. This means the application programmer
         will have to possess some expertise, and put in some effort, to be
         able to utilize multi-pipe rendering with Coin.

       · Rendering traversals is currently the only operation which we
         publicly support to be thread-safe. There are other aspects of Coin
         that we know are thread-safe, like most other action traversals
         beside just rendering, but we make no guarantees in this regard.

       · Be careful about using a separate thread for changing Coin structures
         versus what is used for the application’s GUI event thread.
       We are aware of at least issues with Qt (and thereby SoQt), where you
       should not modify the scene graph in any way in a thread separate from
       the main Qt thread. This because it will trigger operations where Qt is
       not thread-safe.

           Coin 2.0