Comment 1 for bug 1042404

As for solutions, I obviously don't like b), because it is too much work for probably a small number of users. So I would vote for a).

In the first round, it might be enough to solve problem b), i.e. the problem with the Python interface. Plus we can document that people attaching attribute handlers in multithreaded programs should attach an attribute handler from each thread that is calling igraph functions. (Bad, but there are not too many people doing this, I believe.)