Merge pull request #22204 from akka/wip-22197-promote-WeaklyUp-patriknw

Promote WeaklyUp and enable by default, #22197
This commit is contained in:
Patrik Nordwall 2017-01-24 14:38:13 +01:00 committed by GitHub
commit 261a04714e
14 changed files with 41 additions and 64 deletions

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@ -30,7 +30,7 @@ and add the following configuration stanza to your ``application.conf``
akka.extensions = [ "akka.cluster.metrics.ClusterMetricsExtension" ]
Cluster members with status :ref:`WeaklyUp <weakly_up_java>`, if that feature is enabled,
Cluster members with status :ref:`WeaklyUp <weakly_up_java>`,
will participate in Cluster Metrics collection and dissemination.
Metrics Collector

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@ -53,8 +53,7 @@ It's worth noting that messages can always be lost because of the distributed na
As always, additional logic should be implemented in the singleton (acknowledgement) and in the
client (retry) actors to ensure at-least-once message delivery.
The singleton instance will not run on members with status :ref:`WeaklyUp <weakly_up_java>` if that feature
is enabled.
The singleton instance will not run on members with status :ref:`WeaklyUp <weakly_up_java>`.
Potential problems to be aware of
---------------------------------

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@ -206,32 +206,19 @@ If a node is ``unreachable`` then gossip convergence is not possible and therefo
``leader`` actions are also not possible. However, we still might want new nodes to join
the cluster in this scenario.
.. warning::
The WeaklyUp feature is marked as **“experimental”** as of its introduction in Akka 2.4.0. We will continue to
improve this feature based on our users feedback, which implies that while we try to keep incompatible
changes to a minimum the binary compatibility guarantee for maintenance releases does not apply this feature.
This feature is disabled by default. With a configuration option you can allow this behavior::
akka.cluster.allow-weakly-up-members = on
When ``allow-weakly-up-members`` is enabled and there is no gossip convergence,
``Joining`` members will be promoted to ``WeaklyUp`` and they will become part of the
cluster. Once gossip convergence is reached, the leader will move ``WeaklyUp``
``Joining`` members will be promoted to ``WeaklyUp`` and become part of the cluster if
convergence can't be reached. Once gossip convergence is reached, the leader will move ``WeaklyUp``
members to ``Up``.
This feature is enabled by default, but it can be disabled with configuration option::
akka.cluster.allow-weakly-up-members = off
You can subscribe to the ``WeaklyUp`` membership event to make use of the members that are
in this state, but you should be aware of that members on the other side of a network partition
have no knowledge about the existence of the new members. You should for example not count
``WeaklyUp`` members in quorum decisions.
.. warning::
This feature is only available from Akka 2.4.0 and cannot be used if some of your
cluster members are running an older version of Akka.
.. _cluster_subscriber_java:
Subscribe to Cluster Events
@ -500,8 +487,7 @@ automatically unregistered from the router. When new nodes join the cluster addi
routees are added to the router, according to the configuration. Routees are also added
when a node becomes reachable again, after having been unreachable.
Cluster aware routers make use of members with status :ref:`WeaklyUp <weakly_up_java>` if that feature
is enabled.
Cluster aware routers make use of members with status :ref:`WeaklyUp <weakly_up_java>`.
There are two distinct types of routers.

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@ -42,7 +42,7 @@ with a specific role. It communicates with other ``Replicator`` instances with t
actor using the ``Replicator.props``. If it is started as an ordinary actor it is important
that it is given the same name, started on same path, on all nodes.
Cluster members with status :ref:`WeaklyUp <weakly_up_java>`, if that feature is enabled,
Cluster members with status :ref:`WeaklyUp <weakly_up_java>`,
will participate in Distributed Data. This means that the data will be replicated to the
:ref:`WeaklyUp <weakly_up_java>` nodes with the background gossip protocol. Note that it
will not participate in any actions where the consistency mode is to read/write from all

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@ -22,7 +22,7 @@ a few seconds. Changes are only performed in the own part of the registry and th
changes are versioned. Deltas are disseminated in a scalable way to other nodes with
a gossip protocol.
Cluster members with status :ref:`WeaklyUp <weakly_up_java>`, if that feature is enabled,
Cluster members with status :ref:`WeaklyUp <weakly_up_java>`,
will participate in Distributed Publish Subscribe, i.e. subscribers on nodes with
``WeaklyUp`` status will receive published messages if the publisher and subscriber are on
same side of a network partition.