feat: configure database connection pool settings

[Alwayswithme]

Description

Changed default connection pool configuration for all database drivers.

Implementation Details

Based on benchmark testing and research, I found setting max connections to twice the number of CPU cores provides an optimal balance between performance and resource utilization, as shown in the benchmark results. However, I'm open to discussion on these specific values:

cores := runtime.NumCPU()
driver.GetDB().SetMaxOpenConns(cores * 2)      // **Should this be cores * 2?**
driver.GetDB().SetMaxIdleConns(cores)  // **Is half of max connections appropriate?**
driver.GetDB().SetConnMaxLifetime(time.Minute * 5)

Review Questions

1. Are these default values appropriate for most use cases?
2. Should we make these values configurable via config file?

References

• About-Pool-Sizing
• sql.DB docs
• go-sql-driver/mysql docs

Benchmark

Tested with SQLite driver on Linux (Intel i5-3230M @ 2.60GHz, 2 cores/4 threads):

goos: linux
goarch: amd64
pkg: github.com/usememos/memos/store/test
cpu: Intel(R) Core(TM) i5-3230M CPU @ 2.60GHz
BenchmarkDBConnPool/default_unlimited-4         	     100	  49079319 ns/op	         0 wait_count	         0 wait_duration_ms	   12509 B/op	      94 allocs/op
BenchmarkDBConnPool/max_conns_equals_cores-4    	     127	   9230205 ns/op	       123.0 wait_count	     54868 wait_duration_ms	    1963 B/op	      53 allocs/op
BenchmarkDBConnPool/max_conns_double_cores-4    	     100	  11410104 ns/op	        92.00 wait_count	     29387 wait_duration_ms	    3155 B/op	      55 allocs/op
BenchmarkDBConnPool/max_conns_25-4              	     100	  20643346 ns/op	        74.00 wait_count	     19161 wait_duration_ms	    3640 B/op	      60 allocs/op
BenchmarkDBConnPool/max_conns_50-4              	     100	  41783602 ns/op	        50.00 wait_count	      9294 wait_duration_ms	    4428 B/op	      68 allocs/op
BenchmarkDBConnPool/max_conns_100-4             	     100	  36894592 ns/op	         0 wait_count	         0 wait_duration_ms	    5111 B/op	      83 allocs/op
PASS
ok  	github.com/usememos/memos/store/test	20.815s

[Copilot]

Pull Request Overview

This PR updates the default database connection pool configurations and adds benchmark tests to compare various connection pool settings based on CPU cores.

• Sets default values for max open connections, max idle connections, and connection max lifetime in the driver initialization.
• Introduces benchmark tests to evaluate different connection pool settings and report connection pool metrics.

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
store/test/store_bench_test.go	Adds benchmark tests for multiple connection pool configurations.
store/db/db.go	Updates default DB connection pool settings derived from the number of CPU cores.

Comments suppressed due to low confidence (2)

store/test/store_bench_test.go:28

• [nitpick] Consider renaming 'lifeTime' to 'connMaxLifetime' for clarity and consistency with the parameter it configures.

lifeTime := time.Hour

store/test/store_bench_test.go:126

• [nitpick] Consider uncommenting and reporting additional metrics (max_open_conns, conns_in_use, idle_conns) to provide a more comprehensive view of the connection pool performance in benchmarks.

// b.ReportMetric(float64(endStats.MaxOpenConnections), "max_open_conns")

[johnnyjoygh]

• Are these default values appropriate for most use cases?
• Should we make these values configurable via config file?

We currently haven't got any performance issues related to the database based on user feedback, so I think we can first add a flag to control it and avoid a breaking change (even though it's a good change).