[jira] [Created] (YARN-1076) RM gets stuck with a reservation, ignoring new containers

["Maysam Yabandeh (JIRA)" <ji...@apache.org>]

Maysam Yabandeh created YARN-1076:
-------------------------------------

             Summary: RM gets stuck with a reservation, ignoring new containers
                 Key: YARN-1076
                 URL: https://issues.apache.org/jira/browse/YARN-1076
             Project: Hadoop YARN
          Issue Type: Bug
          Components: resourcemanager
            Reporter: Maysam Yabandeh
            Priority: Minor


LeafQueue#assignContainers rejects newly available containers if #needContainers returns false:
{code:java}
          if (!needContainers(application, priority, required)) {
            continue;
          }
{code}

When the application has already reserved all the required containers, #needContainers returns false as long as no starvation is reported:
{code:java}
return (((starvation + requiredContainers) - reservedContainers) > 0);
{code}

where starvation is computed based on the attempts on re-reserving a resource. On the other hand, a resource is re-reserved via #assignContainersOnNode only if it passed the #needContainers precondition:
{code:java}
          // Do we need containers at this 'priority'?
          if (!needContainers(application, priority, required)) {
            continue;
          }

          //.
          //.
          //.
          
          // Try to schedule
          CSAssignment assignment =  
            assignContainersOnNode(clusterResource, node, application, priority, 
                null);
{code}

In other words, once needContainers returns false due to a reservation, it keeps rejecting newly available resources, since no reservation is ever attempted.

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