__IN_ONNX_EXPORT variable in torch.onnx.export

I’ve noticed the global variable __IN_ONNX_EXPORT in torch.onnx.utils that is supposed to prevent calling the torch.onnx.export again while the previous is still in progress. I’ve tried to find documentation about why it should be prevented, with no success. Does that means that the torch.onnx.export can’t be distributed across threads?