[FEATURE] Sesssion connections are unbalanced in the instance of the engine pool

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#4,342 opened on Feb 16, 2023 2 comments 0 reactions 0 assignees View on GitHub

kind:feature priority:major

Description

### Code of Conduct

- [X] I agree to follow this project's [Code of Conduct](https://www.apache.org/foundation/policies/conduct)

### Search before asking

- [X] I have searched in the [issues](https://github.com/apache/kyuubi/issues?q=is%3Aissue) and found no similar issues.

### Describe the feature

engine.pool.size = 4
kyuubi.engine.pool.selectPolicy=POLLING
jdbc pool size = 40

Session connections are unbalanced across instances:

engine01:
![image](https://user-images.githubusercontent.com/8111349/219330595-8b2a970b-ca12-44e8-a3de-b15189dbfee1.png)

engine02:
![image](https://user-images.githubusercontent.com/8111349/219330539-70f032a5-7ad0-4b38-8c65-cb94da60f5b3.png)

engine03:
![image](https://user-images.githubusercontent.com/8111349/219330748-ce25877f-fefe-403f-965c-0b0a7ad8dcc5.png)

engine04:
![image](https://user-images.githubusercontent.com/8111349/219330831-533853d6-772b-447f-b31a-11c5fa28759d.png)

### Motivation

Unbalanced connections will cause unbalanced engine load.
Some engines perform a lot of calculations, while the rest are idle.

### Describe the solution

_No response_

### Additional context

_No response_

### Are you willing to submit PR?

- [ ] Yes. I would be willing to submit a PR with guidance from the Kyuubi community to improve.
- [ ] No. I cannot submit a PR at this time.

This issue has not been assessed yet.