[DSIP-31] Reduce the connection pool size of hikari

[Wenjun Ruan]

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Motivation

I am not clear why we set the hikari thread pool size, I don't find out any benchmark test result.

Following https://github.com/brettwooldridge/HikariCP/wiki/About-Pool-Sizing, I hope to remove some configurations of hikari, the default setting is great enough. We shouldn't change the default setting unless we have benchmark evidence.

dolphinscheduler/dolphinscheduler-api/src/main/resources/application.yaml

Lines 52 to 62 in e66441a

 hikari: 
   connection-test-query: select 1 
   minimum-idle: 5 
   auto-commit: true 
   validation-timeout: 3000 
   pool-name: DolphinScheduler 
   maximum-pool-size: 50 
   connection-timeout: 30000 
   idle-timeout: 600000 
   leak-detection-threshold: 0 
   initialization-fail-timeout: 1 

Design Detail

Only keep the pool name and connection-test-query
hikari:
connection-test-query: select 1
pool-name: DolphinScheduler

Compatibility, Deprecation, and Migration Plan

Compatible with all version.

Test Plan

Test by e2e.

Code of Conduct

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