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https://issues.apache.org/jira/browse/YARN-6163?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15862032#comment-15862032
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ASF GitHub Bot commented on YARN-6163:
--------------------------------------
Github user templedf commented on a diff in the pull request:
https://github.com/apache/hadoop/pull/192#discussion_r100642853
--- Diff:
hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/fair/FSLeafQueue.java
---
@@ -220,6 +220,62 @@ public void updateInternal(boolean checkStarvation) {
}
/**
+ * Compute the extent of fairshare starvation for a set of apps.
+ *
+ * @param appsWithDemand apps to compute fairshare starvation for
+ * @return aggregate fairshare starvation for all apps
+ */
+ private Resource updateStarvedAppsFairshare(
+ TreeSet<FSAppAttempt> appsWithDemand) {
+ Resource fairShareStarvation = Resources.clone(none());
+ // Fetch apps with unmet demand sorted by fairshare starvation
+ for (FSAppAttempt app : appsWithDemand) {
+ Resource appStarvation = app.fairShareStarvation();
+ if (!Resources.isNone(appStarvation)) {
+ context.getStarvedApps().addStarvedApp(app);
+ Resources.addTo(fairShareStarvation, appStarvation);
+ } else {
+ break;
+ }
+ }
+ return fairShareStarvation;
+ }
+
+ /**
+ * Distribute minshare starvation to a set of apps
+ * @param appsWithDemand set of apps
+ * @param minShareStarvation minshare starvation to distribute
+ */
+ private void updateStarvedAppsMinshare(
+ TreeSet<FSAppAttempt> appsWithDemand, Resource minShareStarvation) {
+ // Keep adding apps to the starved list until the unmet demand goes
over
+ // the remaining minshare
+ for (FSAppAttempt app : appsWithDemand) {
+ if (!Resources.isNone(minShareStarvation())) {
+ Resource appMinShare = app.getPendingDemand();
+ Resources.subtractFromNonNegative(
+ appMinShare, app.getFairshareStarvation());
+
+ if (Resources.greaterThan(policy.getResourceCalculator(),
+ scheduler.getClusterResource(),
+ appMinShare, minShareStarvation)) {
+ Resources.subtractFromNonNegative(
+ appMinShare, minShareStarvation);
+ minShareStarvation = none();
--- End diff --
Not a fan of modifying an arg.
> FS Preemption is a trickle for severely starved applications
> ------------------------------------------------------------
>
> Key: YARN-6163
> URL: https://issues.apache.org/jira/browse/YARN-6163
> Project: Hadoop YARN
> Issue Type: Sub-task
> Components: fairscheduler
> Affects Versions: 2.9.0
> Reporter: Karthik Kambatla
> Assignee: Karthik Kambatla
> Attachments: yarn-6163-1.patch
>
>
> With current logic, only one RR is considered per each instance of marking an
> application starved. This marking happens only on the update call that runs
> every 500ms. Due to this, an application that is severely starved takes
> forever to reach fairshare based on preemptions.
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