Comment 32 for bug 401823

Improving the algorithm providing the XID range so that it provided a larger range where possible would make this less likely (though it could still happen less often in reasonable circumstances).

Keeping a buffer of a certain number of recently released XIDs is another possibility.

Or perhaps calculating the range in advance, so that the range used is a range of XIDs that were available (but not advertised) at the time of a previous range request.