Multithreading

Early versions of the OrcFxAPI DLL were not thread safe. This means that multiple threads of the same process could not safely call OrcFxAPI functions concurrently. Starting with version 9.2, the OrcFxAPI DLL is now thread safe in the sense that different threads can operate on different models concurrently.

Models have affinity to a particular thread. That is, all calls to functions which operate on a particular model, or objects within that model, must be made from the same thread. When a model is created it has affinity to the thread in which it is created. A model can be assigned affinity to a different thread by taking the following steps:

1. Call C_DetachFromThread from the thread to which the model currently has affinity.
2. Call C_AttachToThread from a different thread, after which the model will have affinity to this thread.

There are special implications for external function thread safety.