[ https://issues.apache.org/jira/browse/YARN-8436?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16549803#comment-16549803 ]
Haibo Chen commented on YARN-8436: ---------------------------------- I see. +1 on the latest patch. Will check it into trunk shortly. > FSParentQueue: Comparison method violates its general contract > -------------------------------------------------------------- > > Key: YARN-8436 > URL: https://issues.apache.org/jira/browse/YARN-8436 > Project: Hadoop YARN > Issue Type: Bug > Components: fairscheduler > Affects Versions: 3.1.0 > Reporter: Wilfred Spiegelenburg > Assignee: Wilfred Spiegelenburg > Priority: Minor > Attachments: YARN-8436.001.patch, YARN-8436.002.patch, > YARN-8436.003.patch > > > The ResourceManager can fail while sorting queues if an update comes in: > {code:java} > FATAL org.apache.hadoop.yarn.server.resourcemanager.ResourceManager: Error in > handling event type NODE_UPDATE to the scheduler > java.lang.IllegalArgumentException: Comparison method violates its general > contract! > at java.util.TimSort.mergeLo(TimSort.java:777) > at java.util.TimSort.mergeAt(TimSort.java:514) > ... > at java.util.Collections.sort(Collections.java:175) > at > org.apache.hadoop.yarn.server.resourcemanager.scheduler.fair.FSParentQueue.assignContainer(FSParentQueue.java:223){code} > The reason it breaks is a change in the sorted object itself. > This is why it fails: > * an update from a node comes in as a heartbeat. > * the update triggers a check to see if we can assign a container on the > node. > * walk over the queue hierarchy to find a queue to assign a container to: > top down. > * for each parent queue we sort the child queues in {{assignContainer}} to > decide which queue to descent into. > * we lock the parent queue when sort to prevent changes, but we do not lock > the child queues that we are sorting. > If during this sorting a different node update changes a child queue then we > allow that. This means that the objects that we are trying to sort now might > be out of order. That causes the issue with the comparator. The comparator > itself is not broken. -- This message was sent by Atlassian JIRA (v7.6.3#76005) --------------------------------------------------------------------- To unsubscribe, e-mail: yarn-issues-unsubscr...@hadoop.apache.org For additional commands, e-mail: yarn-issues-h...@hadoop.apache.org