> I was wondering: how often do nanosecond timestamps collide on modern systems? The answer is: very often, like 5% of all samples, when reading the clock on al

> I was wondering: how often do nanosecond timestamps collide on modern systems? The answer is: very often, like 5% of all samples, when reading the clock on all 4 physical cores at the same time. A few things to consider: 1. This would depend a lot on how regularly you are checking, the more regular, the more collisions. 2. There may also be some weirdness where threads doing similar tasks will synchronise or desynchronise to maximize throughput. 3. Your system may not offer accurate nanosecond time. For this reason some OSes tend not to offer lower than microsecond time, as the clocks simply cannot offer higher usable accuracy. You're also measuring the time to call the function(s), create the timestamp, etc. A simple solution I had years ago was to add random precision to reduce collisions. That breaks most tie situations. If you have 5% ties in nano seconds, with random pico second accuracy your collisions are down to 0.005%. You could also seed the random offset by an ID.