Sietse T. Au created YARN-1902:
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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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