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https://issues.apache.org/jira/browse/YARN-1042?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15733903#comment-15733903
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Konstantinos Karanasos commented on YARN-1042:
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Hi [~leftnoteasy]. Thanks for working on this. Being able to specify
(anti-)affinity constraints is a feature that we are very interested in as well.
I gave a quick look at your patch. As I mentioned to you in the past, we also
have a working prototype for defining and imposing similar constraints (I had
uploaded an initial version of it at YARN-4902 some time back). We can share
more code if it helps.
For now let's focus on the API -- we can later discuss how to make the
scheduling efficient (e.g., using the global scheduling and so on).
I would suggest to unify the affinity and anti-affinity constraints and make
them a bit more general too. For instance, we can specify "cardinality"
constraints of the form "put no more than 4 HBase masters at each rack". This
constraint is useful but cannot be captured by pure affinity or anti-affinity
constraints.
I assume that its task can be associated with a set of labels (similar to the
ones we are discussing in YARN-3409). This is not there at the moment, but can
be added.
Then, we could use the following placement constraint form: {noformat} {task,
target-tasks, cluster-scope, min-cardinality, max-cardinality}. {noformat}
In the above constraint, {{task}} is a specific task, {{target-tasks}} is a
label (e.g., "HBase-master", "app_000123" or "latency-critical") that specifies
a set of tasks that are already scheduled in the cluster, {{cluster-scope}} is
something among NODE and RACK (and possibly others in the future),
{{min-cardinality}} is the minimum number of tasks with label {{target-tasks}}
that can appear at the same {{cluster-scope}} with {{task}}, and
{{max-cardinality}} is the respective maximum cardinality.
Using the {{min-}} and {{max-cardinality}}, we can specify affinity,
anti-affinity and other cardinality constraints.
For example, {task_001, "HBase-master", NODE, 1, 1} is an anti-affinity
constraint (don't put more than one HBase master at a node.
Likewise, {task_001, "HBase-region-server", NODE, 2, MAX_INT} is an affinity
constraint for region servers.
Let me know how it looks.
> add ability to specify affinity/anti-affinity in container requests
> -------------------------------------------------------------------
>
> Key: YARN-1042
> URL: https://issues.apache.org/jira/browse/YARN-1042
> Project: Hadoop YARN
> Issue Type: Sub-task
> Components: resourcemanager
> Affects Versions: 3.0.0-alpha1
> Reporter: Steve Loughran
> Assignee: Wangda Tan
> Attachments: YARN-1042-demo.patch, YARN-1042-design-doc.pdf,
> YARN-1042-global-scheduling.poc.1.patch, YARN-1042.001.patch,
> YARN-1042.002.patch
>
>
> container requests to the AM should be able to request anti-affinity to
> ensure that things like Region Servers don't come up on the same failure
> zones.
> Similarly, you may be able to want to specify affinity to same host or rack
> without specifying which specific host/rack. Example: bringing up a small
> giraph cluster in a large YARN cluster would benefit from having the
> processes in the same rack purely for bandwidth reasons.
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