[jira] [Created] (YARN-10705) Misleading DEBUG log for container assignment needs to be removed when the container is actually reserved, not assigned in FairScheduler

["Siddharth Ahuja (Jira)" <ji...@apache.org>]

Siddharth Ahuja created YARN-10705:
--------------------------------------

             Summary: Misleading DEBUG log for container assignment needs to be removed when the container is actually reserved, not assigned in FairScheduler
                 Key: YARN-10705
                 URL: https://issues.apache.org/jira/browse/YARN-10705
             Project: Hadoop YARN
          Issue Type: Bug
            Reporter: Siddharth Ahuja


Following DEBUG logs are logged if a container reservation is made when a node has been offered to the queue in FairScheduler:

{code}
2021-02-10 07:33:55,049 DEBUG org.apache.hadoop.yarn.server.resourcemanager.scheduler.fair.FSAppAttempt: application_1610442362681_2607's resource request is reserved.
2021-02-10 07:33:55,049 DEBUG org.apache.hadoop.yarn.server.resourcemanager.scheduler.fair.FSLeafQueue: Assigned container in queue:root.pj_dc_pe container:<memory:-1, vCores:0>
{code}

The latter log from above seems to indicate a bad container assignment with <memory:-1, vCores:0> resource allocation, whereas, in actual, it is a bad log which shouldn't have been logged in the first place.

This log comes from [1] after an application attempt with an unmet demand is checked for container assignment/reservation.

If the container for this app attempt is reserved on the node, then, it returns <memory:-1, vCores:0> from [2].

From [3]:

{quote}
   *     If an assignment was made, returns the resources allocated to the
   *     container.  If a reservation was made, returns
   *     FairScheduler.CONTAINER_RESERVED.  If no assignment or reservation was
   *     made, returns an empty resource.
{quote}

We are checking for the empty resource at [4], but not FairScheduler.CONTAINER_RESERVED before logging out a message for container assignment specifically which is incorrect.

Instead of:

{code}
      if (!assigned.equals(none())) {
        LOG.debug("Assigned container in queue:{} container:{}",
            getName(), assigned);
        break;
      }
{code}

it should be:

{code}
      // check if an assignment or a reservation was made.
      if (!assigned.equals(none())) {
        // only log container assignment if there is
        // an actual assignment, not a reservation.
        if (!assigned.equals(FairScheduler.CONTAINER_RESERVED)
                && LOG.isDebugEnabled()) {
          LOG.debug("Assigned container in queue:" + getName() + " " +
                        "container:" + assigned);
        }
        break;
      }
{code}

[1] https://github.com/apache/hadoop/blob/trunk/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#L356
[2] https://github.com/apache/hadoop/blob/trunk/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/fair/FSAppAttempt.java#L911
[3] https://github.com/apache/hadoop/blob/trunk/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/fair/FSAppAttempt.java#L842
[4] https://github.com/apache/hadoop/blob/trunk/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#L355



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