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https://issues.apache.org/jira/browse/YARN-2628?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14157311#comment-14157311
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Hudson commented on YARN-2628:
------------------------------
SUCCESS: Integrated in Hadoop-trunk-Commit #6183 (See
[https://builds.apache.org/job/Hadoop-trunk-Commit/6183/])
YARN-2628. Capacity scheduler with DominantResourceCalculator carries out
reservation even though slots are free. Contributed by Varun Vasudev (jianhe:
rev 054f28552687e9b9859c0126e16a2066e20ead3f)
*
hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/capacity/CapacityScheduler.java
*
hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/test/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/capacity/TestCapacityScheduler.java
* hadoop-yarn-project/CHANGES.txt
> Capacity scheduler with DominantResourceCalculator carries out reservation
> even though slots are free
> -----------------------------------------------------------------------------------------------------
>
> Key: YARN-2628
> URL: https://issues.apache.org/jira/browse/YARN-2628
> Project: Hadoop YARN
> Issue Type: Bug
> Components: capacityscheduler
> Affects Versions: 2.5.1
> Reporter: Varun Vasudev
> Assignee: Varun Vasudev
> Fix For: 2.6.0
>
> Attachments: apache-yarn-2628.0.patch, apache-yarn-2628.1.patch
>
>
> We've noticed that if you run the CapacityScheduler with the
> DominantResourceCalculator, sometimes apps will end up with containers in a
> reserved state even though free slots are available.
> The root cause seems to be this piece of code from CapacityScheduler.java -
> {noformat}
> // Try to schedule more if there are no reservations to fulfill
> if (node.getReservedContainer() == null) {
> if (Resources.greaterThanOrEqual(calculator, getClusterResource(),
> node.getAvailableResource(), minimumAllocation)) {
> if (LOG.isDebugEnabled()) {
> LOG.debug("Trying to schedule on node: " + node.getNodeName() +
> ", available: " + node.getAvailableResource());
> }
> root.assignContainers(clusterResource, node, false);
> }
> } else {
> LOG.info("Skipping scheduling since node " + node.getNodeID() +
> " is reserved by application " +
>
> node.getReservedContainer().getContainerId().getApplicationAttemptId()
> );
> }
> {noformat}
> The code is meant to check if a node has any slots available for containers .
> Since it uses the greaterThanOrEqual function, we end up in situation where
> greaterThanOrEqual returns true, even though we may not have enough CPU or
> memory to actually run the container.
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