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19.7.1. Group Membership

The group membership service in the JGroups stack maintains a list of active nodes. It handles the requests to join and leave the cluster. It also handles the SUSPECT messages sent by failure detection protocols. All nodes in the cluster, as well as the load balancer and client side interceptors, are notified if the group membership changes. The group membership service is configured in the pbcast.GMS sub-element under the JGroups Config element. Here is an example configuration.

<pbcast.GMS print_local_addr="true"
    down_thread="false" up_thread="false"

The configurable attributes in the pbcast.GMS element are as follows.

  • join_timeout specifies the maximum number of milliseconds to wait for a new node JOIN request to succeed. Retry afterwards.

  • join_retry_timeout specifies the maximum number of milliseconds to wait after a failed JOIN to re-submit it.

  • print_local_addr specifies whether to dump the node's own address to the output when started.

  • shun specifies whether a node should shun itself if it receives a cluster view that it is not a member node.

  • disable_initial_coord specifies whether to prevent this node as the cluster coordinator.

  • view_bundling specifies whether multiple JOIN or LEAVE request arriving at the same time are bundled and handled together at the same time, only sending out 1 new view / bundle. This is is more efficient than handling each request separately.