Does ray use the least-busy worker?

Ray Core
1

How severe does this issue affect your experience of using Ray?

  • None: Just asking a question out of curiosity

I have a cluster of 5 nodes. 8 cores per node. So 40 workers in the cluster.

Suppose I submit a job with 10 tasks. How will Ray decide which workers to send the tasks to? Does it look at how busy each machine is, and send the tasks to the least-busy machine?

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Hi @xydote. Check out this link in the documentation for a high-level explanation of scheduling policies: Scheduling — Ray 2.8.0.

I think this paragraph addresses your question:

“DEFAULT” is the default strategy used by Ray. With the current implementation, Ray will try to pack tasks on nodes until the resource utilization is beyond a certain threshold and spread tasks afterwards.

cc @Chen_Shen who might have additional insight

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