[jira] [Created] (YARN-9099) GpuResourceAllocator.getReleasingGpus calculates number of GPUs in a wrong way

["Szilard Nemeth (JIRA)" <ji...@apache.org>]

Szilard Nemeth created YARN-9099:
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             Summary: GpuResourceAllocator.getReleasingGpus calculates number of GPUs in a wrong way
                 Key: YARN-9099
                 URL: https://issues.apache.org/jira/browse/YARN-9099
             Project: Hadoop YARN
          Issue Type: Bug
            Reporter: Szilard Nemeth
            Assignee: Szilard Nemeth


getReleasingGpus plays an important role in the calculation which happens when GpuAllocator assign GPUs to a container, see: GpuResourceAllocator#internalAssignGpus.

If multiple GPUs are assigned to the same container, getReleasingGpus will return an invalid number.
The iterator goes over on mappings of (GPU device, container ID) and it retrieves the container by its ID the number of times the container ID is mapped to any device.
Then for every container, the resource value for the GPU resource is added to a running sum.
Obviously, if a container is mapped to 2 or more devices, then the container's GPU resource counter is added to the running sum as many times as the number of GPU devices the container has.

Example: 
Let's suppose {{usedDevices}} contains these mappings: 
- (GPU1, container1)
- (GPU2, container1)
- (GPU3, container2)

GPU resource value is 2 for container1 and 
GPU resource value is 1 for container2.
Then, if container1 is in a running state, getReleasingGpus will return 4 instead of 2.



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