Model is not threadsafe

[chrisdembia]

I am trying to use a Model in a multithreaded setting. I had a separate State per thread, but wanted to share the model between threads. This led to confusing errors. I then created a separate Model per thread, and my problem went away.

It would be nice if the Models were threadsafe. My intuition was that all I would need are separate State objects, if we consider our models/system to be "const". However, if this is hard to fix, it may not be worth it, because the fix is to just use multiple copies of the model. If we decide not to make models threadsafe, then we can maybe just mention in doxygen that they aren't threadsafe.

[chrisdembia]

The issue seemed to happen with realizing measures. I didn't thoroughly investigate though.

[sherm1]

Models should be threadsafe after construction, followed by whatever call in OpenSim finalizes data structures contained in Model objects. I think if they aren't threadsafe there is a bug somewhere.

[PeterJiang89]

i have met with the same problem. The model seems thread safe, but the destructor doesn't do the clean up of the storage generated during the simulation by analyzers. Hope someone could fix it for us.

[chrisdembia]

@PeterJiang89 if you know of a specific issue and have an idea of how to solve it, you can submit a pull request :)

[chrisdembia]

Though you should discuss with us first how you'd like to solve the problem (see our contributing guidelines: https://github.com/opensim-org/opensim-core/blob/master/CONTRIBUTING.md).