Hi @pierhugues, thank for the tip.
But if that's the default behaviour, as you have said, then I would consider this to be a bug that in default setup and pretty standard use case the log file of a running service gets corrupted. What's more, since it's happening without any warning, the problem might pass unnoticed until much later when there is an actual need to check service logs.
Should I submit a ticket in beats issue tracker then?