Methods, devices and systems for dynamically managing memberships in replicated state machines within a distributed computing environment
A computer-implemented method may comprise processing agreements received over a computer network at a first replicated state machine deployed on processes belonging to a first membership in an order defined by a first globally ordered set of agreements associated with the first membership; receiving an agreement to change membership that is configured to cause the first replicated state machine to be deployed on processes belonging to a second membership that is associated with a second globally ordered set of agreements; and processing the agreement to change membership at a point within the first globally ordered set of agreements.
1. A computer-implemented method, comprising:
replicating states of a state machine in a plurality of state machines over a computer network to create a plurality of replicated state machines;
associating the plurality of replicated state machines with a plurality of processes and with a first globally ordered set of agreements that is visible to and maintains a consistency of all replicated state machines;
changing the plurality of processes associated with the plurality of replicated state machines at an arbitrary point in the first globally ordered set of agreements; and
enabling at least some of the plurality of processes associated with the plurality of replicated state machines to change states while the change to the plurality of processes is being made.
2. The computer-implemented method of claim 1 , wherein changing comprises changing a role of at least one of the plurality of processes.
3. The computer-implemented method of claim 2 , wherein changing the role comprises changing the role of the at least one of the plurality of processes to one of proposer, acceptor and learner.
4. The computer-implemented method of claim 1 , wherein changing comprises one of changing a number of the plurality of processes and changing all processes associated with the plurality of replicated state machines.
5. The computer-implemented method of claim 1 , further comprising completing the change to the plurality of processes and associating the plurality of replicated state machines with the changed plurality of processes and with a second globally ordered set of agreements.
6. The computer-implemented method of claim 1 , wherein the plurality of processes belong to a first membership and wherein changing the plurality of processes comprises changing the association of the plurality of replicated state machines to a second membership comprising the changed plurality of processes.
7. The computer-implemented method of claim 1 , further comprising receiving, at each of the replicated state machines, agreements to be processed at a point within the first globally ordered set of agreements.
8. The computer-implemented method of claim 7 , wherein receiving comprises receiving the agreements for processing asynchronously and out of an order defined by the first globally ordered set of agreements.
9. The computer-implemented method of claim 7 , wherein changing the plurality of processes associated with the plurality of replicated state machines is carried out responsive to receiving an agreement to change from a current membership to a new membership.
10. The computer-implemented method of claim 1 , wherein the first globally ordered set of agreements comprises at least one agreement to change processes associated with the plurality of replicated state machines.
11. The computer-implemented method of claim 1 , wherein changing the plurality of processes associated with the plurality of replicated state machines comprises adding a learner to the plurality of processes without affecting any existing learners learning from the first globally ordered set of agreements.
12. The computer-implemented method of claim 11 , further comprising synchronizing an application state of the added learner after the change to the plurality of processes is complete.