Stuck in glDrawElements

I have a very strange problem. My game engine performs loading of model asynchronously. After that it is added to the rendering loop.

The problem is that sometimes (and it's absolutely random) after model was loaded the execution freezes at glDrawElements. I don't get any EXC_BAD_ACCESS or smth like that.

It seems that all execution is performed inside glD开发者_如何学运维rawElements in some infinite loop. Here is the snapshot that I made in profiler:

Maybe someone knows how glDrawElements works internally and can point me to the possible reason of the problem.