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connection pool: max idle connections implementation #17443

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connection pool: max idle connections implementation #17443

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@harshit-gangal harshit-gangal commented Dec 27, 2024 •
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Description

This PR adds support for maximum idle connection in the pool.
The 3 pools gets it's own parameter for configuration:

  • Non-Streaming: queryserver-config-query-pool-max-idle-count
  • Streaming: queryserver-config-stream-pool-max-idle-count
  • Transaction: queryserver-config-txpool-max-idle-count

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Checklist

  • Tests were added or are not required
  • Did the new or modified tests pass consistently locally and on CI?
  • Documentation was added or is not required

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vitess-bot bot commented Dec 27, 2024

Review Checklist

Hello reviewers! 👋 Please follow this checklist when reviewing this Pull Request.

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@vitess-bot vitess-bot bot added NeedsBackportReason If backport labels have been applied to a PR, a justification is required NeedsDescriptionUpdate The description is not clear or comprehensive enough, and needs work NeedsIssue A linked issue is missing for this Pull Request NeedsWebsiteDocsUpdate What it says labels Dec 27, 2024
@harshit-gangal harshit-gangal removed the NeedsBackportReason If backport labels have been applied to a PR, a justification is required label Dec 27, 2024
@github-actions github-actions bot added this to the v22.0.0 milestone Dec 27, 2024
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codecov bot commented Dec 27, 2024

Codecov Report

Attention: Patch coverage is 73.33333% with 8 lines in your changes missing coverage. Please review.

Project coverage is 67.66%. Comparing base (9383943) to head (10025af).

Files with missing lines Patch % Lines
go/pools/smartconnpool/pool.go 73.33% 8 Missing ⚠️
Additional details and impacted files 
@@            Coverage Diff             @@
##             main   #17443      +/-   ##
==========================================
- Coverage   67.67%   67.66%   -0.01%     
==========================================
  Files        1583     1583              
  Lines      254363   254394      +31     
==========================================
- Hits       172140   172137       -3     
- Misses      82223    82257      +34

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@harshit-gangal harshit-gangal added Type: Feature Component: Query Serving release notes (needs details) This PR needs to be listed in the release notes in a dedicated section (deprecation notice, etc...) and removed NeedsDescriptionUpdate The description is not clear or comprehensive enough, and needs work NeedsIssue A linked issue is missing for this Pull Request labels Jan 7, 2025
@harshit-gangal harshit-gangal marked this pull request as ready for review January 7, 2025 16:12
systay
systay approved these changes Jan 8, 2025
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LGTM 👍

@harshit-gangal
update flag description
1e37131 
Signed-off-by: Harshit Gangal <[email protected]>
@harshit-gangal harshit-gangal removed release notes (needs details) This PR needs to be listed in the release notes in a dedicated section (deprecation notice, etc...) NeedsWebsiteDocsUpdate What it says labels Jan 8, 2025
GrahamCampbell
GrahamCampbell reviewed Jan 8, 2025
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go/pools/smartconnpool/pool.go
@@ -407,6 +432,23 @@ func (pool *ConnPool[C]) put(conn *Pooled[C]) {
}
}

// closeOnIdleLimitReached closes a connection if the number of idle connections (active - inuse) in the pool
// exceeds the idleCount limit. It returns true if the connection is closed, false otherwise.
func (pool *ConnPool[C]) closeOnIdleLimitReached(conn *Pooled[C]) bool {
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Would it be better to not always immediately close, or just close with some random chance, so the connection churn is not really aggressive when there's high active transaction churn?

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We have to maintain a pool of some free available connections, otherwise there will be time spend in acquiring the connection for executing the query.
Even during high transactions, there will be log of get and put call that will happen on the pool, so we have to wait till the free connections become more than a certain limit before we start closing them.
Otherwise the application will see degradation in performance on high QPS

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Right, I said "not always". By which I meant, randomize closing after the idle time had reached.

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Another way to look at it would be to make the idle time random, say between 1x and 2x of the config value, so we don't try and close lots of connections at the same time, after a spike in load.

GuptaManan100
GuptaManan100 approved these changes Jan 9, 2025
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LGTM

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@GuptaManan100 GuptaManan100 GuptaManan100 approved these changes

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Feature Request: Add support for maximum idle connection in the pool
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@harshit-gangal @systay @GrahamCampbell @GuptaManan100