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A JVM that is starting in a core group goes through the following stages before joining the group:
| 1. | Not connected |
The JVM has not established network connectivity with other group members. It will send a single announcement message if the multicast transport mode is used. Or it will send a message to each member of the group if unicast is used. It sends multiple messages in unicast because it doesn't know which other members are started.
| 2. | Connected |
The JVM has already opened a stream to all current members of the installed view. The coordinator considers this JVM as a candidate to join the view. A view is the set of online JVMs ready for running singleton services.
| 3. | In a view |
The JVM is a full participant in a core group at this stage. The view is updated and installed in all members.
When a new view is installed, message HMGR0218I is displayed in the SystemOut.log file of each JVM in the group indicating how many JVMs are currently a member of the view.
Example 6-5 Message HMGR0218I for a new view being installed
[6/20/05 7:28:44:458 CDT] 00000018 CoordinatorIm I HMGR0218I: A new core group view has been installed. The view identifier is (9:0.wascell01\wasna01\nodeagent). The number of members in the new view is 6.
JVMs in the current view constantly try to discover others that are not in the view. Each in-view JVM periodically tries to open sockets to JVMs that are not in the current view. This process continues until all JVMs in the core group are in the view.
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Attention: When running a large number of JVMs on a single box, the operating system might need to be tuned to prevent running out of ephemeral ports. Consult your operating system documentation for details. |
