4 ms·
Does having a co-ordinated view of changes across a system also require some kind of notion of time? (At the least, a tick whenever some kind of changes happen?
by jbert 14y ago
Does having a co-ordinated view of changes across a system also require some kind of notion of time? (At the least, a tick whenever some kind of changes happen?).
Are there any insights to be gained over comparing this idealised view of time and physical time?
e.g. I don't really see that relativity comes into play but could it/should it?
There could be some kind of analogue for how changes spread around a distributed system, which is limited by the effective propogation speed of the system.
Do we run into some kind of underlying law of distributed systems about the inability to have a reliable, cross-system change-based "tick"? (e.g. could that be a consequence of the CAP theorem? http://en.wikipedia.org/wiki/CAP_theorem http://en.wikipedia.org/wiki/CAP_theorem)
- nickray 14y agoRegarding your second question, I suggest reading this classic article by Leslie Lamport: http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CF0QFjAA&url=http%3A%2F%2Fcnlab.kaist.ac.kr%2F~ikjun%2Fdata%2FCourse_work%2FCS642-Distributed_Systems%2Fpapers%2Flamport1978.pdf&ei=HGb0T5yDOoXesgbit_mTBQ&usg=AFQjCNGaOeifWOgXyUoEgaLTwZmNXeN50g http://www.google.com/url?sa=t&rct=j&q=&esrc=s&#...
- jbert 14y agoThanks, that's a great paper (above link is timing out, I got it from this page): http://research.microsoft.com/en-us/um/people/lamport/pubs/pubs.html#time-clocks http://research.microsoft.com/en-us/um/people/lamport/pubs/p...
- Retric 14y agoNot really you can keep objects locked independently. A->A(30)->A(29)...A(0) B->B(20)->B(19)...B(0) start adding a new A; start adding a new B; Finish adding a new A; Finish adding a new B; Verify B; Verify A; A->A(31)->A(30)->A(29)...A(0) B->B(21)->B(20)->B(19)...B(0) Now keep A and B's states stored on different machines and they become completely independent with no concept of time or ticks being introduced. As to an actual example of this in use think bank accounts in an MMO, you might want a transaction log, but you don't necessarily care about time-stamps all that much.