Persistent group membership in a distributing computing system
View Patent ↗A distributed system has a multiplicity of nodes. A group of the nodes subscribe to a group services process. The group is subject to dissolving. A list of persistent subscribers to the group is maintained. Subscriptions to members and states of the group that are persistent subscribers do not terminate in response to the group being dissolved. The persistent subscribers automatically receive a notice in response to the group being reestablished and do not need to re-subscribe to the group.
1. A non-transitory computer readable storage medium for maintaining persistent group memberships in a distributed computer system, the computer readable storage medium comprising programming instructions for:
operating a distribution computing system with a plurality of processing nodes;
running at least one group service program for maintaining groups on at least one of the processing nodes, where each group maintains application specific information for a collection of processing resources, whereby at least two of the processing nodes operate as a plurality of subscriber nodes for subscribing to at least one of the groups as persistent subscriber nodes;
maintaining a persistent subscriber node list of persistent subscriber nodes after the group dissolves so that subscription information is maintained;
dissolving the at least one group so that a number of members in the group is zero; and
notifying the persistent subscriber nodes listed in the persistent subscriber node list, in response to a group being reestablished indicating that the number of members of the group is non-zero, thereby eliminating a need for the persistent subscribers to re-subscribe to the group after it has been reestablished.
2. The computer readable storage medium according to claim 1 , further comprising the instructions for:
receiving a persistent subscriber request from at least one of the plurality of subscriber nodes; and
adding the node to the persistent subscriber node list in response to the persistent subscriber request.
3. The computer readable storage medium according to claim 2 , wherein the persistent subscriber node list excludes nodes of the plurality of subscriber nodes where a corresponding persistent subscriber request has not been received.
4. The computer readable storage medium according to claim 2 , wherein the programming instructions are performed in a first node of the plurality of subscriber nodes and the computer readable storage medium further comprises instructions for
communicating the persistent subscriber request from another of the plurality of subscriber nodes to the first node.
5. The computer readable storage medium according to claim 1 , further comprising the instructions for:
determining a reestablishment of the at least one dissolved group; and
communicating a reestablishment notice indicative thereof to the nodes of the persistent subscriber node list.
6. The computer readable storage medium according to claim 5 , wherein the reestablishment is not communicated to any of the plurality of subscriber nodes not included in the persistent subscriber node list.
7. The computer readable storage medium according to claim 5 , further comprising the instructions for:
receiving a persistent subscriber request from at least one of the plurality of subscriber nodes; and
adding the node to the persistent subscriber node list in response to the persistent subscriber request.
8. The computer readable storage medium according to claim 7 , wherein the persistent subscriber node list excludes nodes of the plurality of subscriber nodes where a corresponding persistent subscriber request was not received and further wherein the reestablishment is not communicated to any of the plurality of subscriber nodes not included in the persistent subscriber node list.
9. The computer readable storage medium according to claim 8 , wherein the programming instructions are performed in a first node of the plurality of processing nodes and the computer readable storage medium further comprises programming instructions performed in one of the plurality of subscriber nodes for:
communicating the persistent request to the first node;
exiting the dissolvable group in response to the group dissolving;
receiving the reestablishment notice from the first node; and
automatically rejoining the dissolved group in response thereto.
10. The computer readable storage medium according to claim 1 , further comprising programming instructions for:
communicating from one of the plurality of subscriber nodes a persistent subscriber request to be included on a persistent subscriber node list of at least some of the plurality of subscriber nodes of the dissolvable group after the group dissolves.
11. The computer readable storage medium according to claim 10 , further comprising instructions for:
exiting the dissolvable group in response to the group dissolving;
receiving a reestablishment notice indicative of a reestablishment of the group; and
automatically rejoining the group in response thereto.