Exam Certified Data Engineer Professional topic 1 question 50 discussion

Option E: In a Spark cluster, the driver node is responsible for managing the execution of the Spark application, including scheduling tasks, managing the execution plan, and interacting with the cluster manager. If the overall cluster CPU utilization is low (e.g., around 25%), it may indicate that the driver node is not utilizing the available resources effectively and might be a bottleneck.

bottleneck means data skew means one of the nodes is doing majority of work while other is idle, so E is correct

D also means that Driver never send big data chunks to the Worker nodes but as it is not mentioned to be 0 then it has a constant flow of data going in & out between the Driver node and the Worker nodes. Therefore it is not a measure of Driver bottleneck. However Answer E means one of the 4 cluster nodes is always working at 100% which can not be other than the Driver node as it is always working and coordinating work across Executors.

Executors talk between each other and between nodes, if the code/driver is working as intended you would see a spike in I/O while transferring data. If the code/driver was the issue you would see a spike in CPU usage and little network traffic between nodes. The correct answer is D.

E is correct

If there's no IO between driver and executor nodes then the executor nodes are not working

D seems to be right

E is correct

25% indicates Cluster CPU under-utilized

If the overall cluster CPU utilization is around 25%, it means that only one out of the four nodes (driver + 3 executors) is using its full CPU capacity, while the other three nodes are idle or underutilized

If the overall cluster CPU utilization is around 25%, it means that only one out of the four nodes (driver + 3 executors) is using its full CPU capacity, while the other three nodes are idle or underutilized