Luke Marshall

Okay, so I think I've worked out the threading issue. Though, now **I'm not sure if this is the same problem in the original ticket.** @BenChampion can you try running...

> (That is, similar results.) Thanks for confirming @BenChampion! > Did you manage to reproduce this in C++? Yes. > * Although it seems to make no difference in our...

> I can create a new issue for this. (I can also try making the required changes.) Great! Should be fairly straightforward. I'm happy to review the PR. > I...

FYI: I can reproduce, and I think I might know the fix. Testing now... Having some issues with my dev environment, so might take a little while to verify.

@jajhall - the issue with `readonly_ptr_wrapper` is an easy (one line) fix, however the whole premise behind `readonly_ptr_wrapper` is a bit of a hack that becomes more obvious when trying...

> Thanks. I wrote the callbacks C-style because it made it simpler to add them to the C API. Clearly it wasn't the best idea.... I can appreciate the idea...

> Thanks [@mathgeekcoder](https://github.com/mathgeekcoder)! For the second part of the issue, can I pull the changes now and set a user_solution through python? No, sorry - not yet. I'm almost done,...

@hlinsen I've updated my [branch](https://github.com/mathgeekcoder/HiGHS/tree/luke-fix-2270) with changes. The PR review process may require further changes, and the official build will likely take a while to include this fix. But if...

FYI: @jajhall, I'm not sure if you remember, but `HighsCallbackInput::repairSolution()` will somewhat do this already. When the user provides a partial solution in a callback, this will call the solver...

@jajhall: I wouldn't accept this change. I have thought about returning these as numpy arrays (instead of lists), but this is not the best way to do this - it...