Re: [wildfly-dev] Is there a way to avoid multiple singleton masters
WFLY-68 adds the ability to specify a quorum required for a singleton service to start,
i.e. a partition must have at least Q members in order for a singleton master election to
take place. In general, the quorum value should be int(N/2)+1, where N is the cluster
size. e.g. If your cluster size is 3, it would be advisable to set the quorum size to 2.
You can find an example of building a singleton service with a specified quorum here:
https://github.com/wildfly/wildfly/blob/master/testsuite/integration/clus...
This of course means that any partition that does not have a least Q members will not have
a transaction recovery manager until the partition is healed.
----- Original Message -----
From: "Michael Musgrove" <mmusgrov(a)redhat.com>
To: wildfly-dev(a)lists.jboss.org
Sent: Wednesday, June 18, 2014 10:12:31 AM
Subject: [wildfly-dev] Is there a way to avoid multiple singleton masters
I'd like to have an option of running our transaction recovery manager
as an HA singleton. WFLY-68 implies that the master can run at most once
(even in the presences of network partition) but I don't see how we can
guarantee that. If I hold the service start in a breakpoint then split
the network and then allow another master on the other side of the
partition to become master and then release the breakpoint we will
briefly have two services running. I know using breakpoints is invalid
but surely there are timing windows where the same outcome could
conceivably occur.
Mike
--
Michael Musgrove
Transactions Team
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