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https://issues.apache.org/jira/browse/FLUME-865?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13206622#comment-13206622
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[email protected] commented on FLUME-865:
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Thanks for the patch Juhani. The functionality seems to be progressing well.
Some comments/feedback to consider regarding configuration:
The current implementation of configuration mechanism is such that it allows
you to specify sinks per agent. Each sink is then associated with a channel.
For example, for an agent named "host1" the relevant configuration to tie a
sink named "sink1" to a channel named "channel1" will be as follows:
host1.sinks = sink1 ...
host1.channels = channel1 ...
host1.sinks.sink1.type = avro
host1.sinks.sink1.channel = channel1
If we want to have a failover sink for sink1, say we call it "sink2", then the
key problem is to be able to associate this new sink with previously configured
sink1. Moreover, this change should be backward compatible so that existing
configuration files continue to work. Given these requirements, the following
is a possible solution:
host1.sinks = sink1 sink2 ...
host1.channels = channel1 ...
host1.sinks.sink1.type = avro
host1.sinks.sink1.channel = channel1
...
host1.sinks.sink2.type = avro
host1.sinks.sink2.channel = channel1
...
host1.sinks.groups = group1
host1.sinks.groups.group1.sinks = sink1 sink2
host1.sinks.groups.group1.policy.type = failover
This introduces the notion of sink groups where a group is a named entity that
can define it's own policy. Internally, this can then translate to the
SinkRunner picking a policy implementation backed by an interface to propagate
the event. For example - SinkPolicy.processEvent(Event e).
If no groups are specified, then each sink gets the default policy
implementation that can handle a single sink at a time only. This makes the
change backward compatible and gives enough flexibility to express different
policies. Further, for policy implementations that require more configuration,
it can be easily use extra configuration from within the group configuration,
much like the way a selector gets its configuration.
Your thoughts?
- Arvind
On 2012-02-06 01:12:23, Juhani Connolly wrote:
bq.
bq. -----------------------------------------------------------
bq. This is an automatically generated e-mail. To reply, visit:
bq. https://reviews.apache.org/r/3750/
bq. -----------------------------------------------------------
bq.
bq. (Updated 2012-02-06 01:12:23)
bq.
bq.
bq. Review request for Flume.
bq.
bq.
bq. Summary
bq. -------
bq.
bq. This includes the changes from FLUME-945 and is thus subject to change
with it. I have a separate patch for the diff from 945->865 if someone wants it.
bq.
bq. A failover sink runner is added, along with a SinkRunnerFactory. The
configuration reading is modified so as to read the runner configuration and
pass it to the SinkRunnerFactory.
bq. A failover sink is used by setting the runner type to failover for every
participating sink. In addition each sink assigned to a runner must set the
same runner.name and a unique runner.priority
bq. The runner will poll only the highest priority live sink. Should it fail
by throwing EventDeliveryException, it will throw it into a pile of dead sinks.
Only once all sinks are exhausted are the dead sinks revived.
bq.
bq. Some issues that are outstanding
bq. - Not all sinks throw EventDeliveryException, or have a clear time when
they should be considered "dead". Coupling such sinks with the failover runner
will not result in failover
bq. - Sinks do not have a clear mechanism to test for their liveliness, other
than perhaps polling LifecycleState. However for most sinks lifecyclestate
tends to remain in START even if the sink is unable to do anything(e.g. avro
sink failing to connect)
bq.
bq.
bq. This addresses bug FLUME-865.
bq. https://issues.apache.org/jira/browse/FLUME-865
bq.
bq.
bq. Diffs
bq. -----
bq.
bq.
flume-ng-core/src/main/java/org/apache/flume/sink/FailoverSinkRunner.java
PRE-CREATION
bq. flume-ng-core/src/main/java/org/apache/flume/sink/SinkRunnerFactory.java
PRE-CREATION
bq.
flume-ng-core/src/test/java/org/apache/flume/sink/TestFailoverSinkRunner.java
PRE-CREATION
bq.
flume-ng-node/src/main/java/org/apache/flume/conf/properties/FlumeConfiguration.java
1ee1f8e
bq.
flume-ng-node/src/main/java/org/apache/flume/conf/properties/PropertiesFileConfigurationProvider.java
3d0e366
bq.
flume-ng-node/src/test/java/org/apache/flume/node/TestAbstractLogicalNodeManager.java
34d6010
bq.
bq. Diff: https://reviews.apache.org/r/3750/diff
bq.
bq.
bq. Testing
bq. -------
bq.
bq. All unit tests pass.
bq. A new unit test was added. It creates a memory channel and a failover
runner with 3 sinks that consume a preset number of events then send
EventDeliveryException. Events are fed to the channel and assertions are made
that the runner is failing over to the correct sinks. This test also passes.
bq.
bq. I also tried to run this on a real cluster, with one master source using a
failover runner to three avro sinks which would each fed into separate agents
which I would kill off to test the failover. Unfortunately because of AvroSink
not throwing EventDeliveryException, this test could not be completed
succesfully, and I felt it was beyond the scope of this ticket to modify
AvroSink
bq.
bq.
bq. Thanks,
bq.
bq. Juhani
bq.
bq.
> Implement failover sink
> ------------------------
>
> Key: FLUME-865
> URL: https://issues.apache.org/jira/browse/FLUME-865
> Project: Flume
> Issue Type: New Feature
> Components: Sinks+Sources
> Affects Versions: NG alpha 2
> Reporter: Jarek Jarcec Cecho
> Assignee: Juhani Connolly
> Fix For: v1.1.0
>
> Attachments: FLUME-865.patch
>
>
> It would be nice if the flume-ng would have ability to failover to different
> sink in case that the active one is not responding (e.g. before failing the
> transaction).
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