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From "Sietse T. Au (JIRA)" <j...@apache.org>
Subject [jira] [Created] (YARN-1902) Allocation of too many containers when a second request is done with the same resource capability
Date Fri, 04 Apr 2014 14:52:16 GMT
Sietse T. Au created YARN-1902:
----------------------------------

             Summary: Allocation of too many containers when a second request is done with
the same resource capability
                 Key: YARN-1902
                 URL: https://issues.apache.org/jira/browse/YARN-1902
             Project: Hadoop YARN
          Issue Type: Bug
          Components: client
    Affects Versions: 2.3.0, 2.2.0
            Reporter: Sietse T. Au


Regarding AMRMClientImpl

Scenario 1:
Given a ContainerRequest x with Resource y, when addContainerRequest is called z times with
x, allocate is called and at least one of the z allocated containers is started, then if another
addContainerRequest call is done and subsequently an allocate call to the RM, (z+1) containers
will be allocated, where 1 container is expected.

Scenario 2:
This behavior does not occur when no containers are started between the allocate calls. 

Analyzing debug logs of the AMRMClientImpl, I have found that indeed a (z+1) are requested
in both scenarios, but that only in the second scenario, the correct behavior is observed.

Looking at the implementation I have found that this (z+1) request is caused by the structure
of the remoteRequestsTable. The consequence of Map<Resource, ResourceRequestInfo> is
that ResourceRequestInfo does not hold any information about whether a request has been sent
to the RM yet or not.

There are workarounds for this, such as releasing the excess containers received.

The solution implemented is to initialize a new ResourceRequest in ResourceRequestInfo when
a request has been successfully sent to the RM.





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