How to solve the connection pool expansion problem of concurrent database connections in Go language?

How to solve the connection pool expansion problem of concurrent database connections in Go language?

Introduction:

In the Go language, database operations are a common concurrency scenario. When multiple goroutines need to access the database at the same time, in order to avoid frequently opening and closing database connections, we usually use a connection pool to manage the reuse of database connections. However, the size of the connection pool is limited, and when concurrent requests increase, the connection pool may become full. In order to solve this problem, we need to implement a connection pool expansion mechanism.

Basic implementation of connection pool:

First, we need to implement a basic connection pool. We can use sync.Pool to manage connection objects. The connection object can be a database connection structure, pointer, or other custom type. We store the connection object in a variable of type sync.Pool. The connection object needs to implement a Close() method to close the connection.

The following is a basic connection pool code example:

package main

import (
    "database/sql"
    "sync"
)

type Conn struct {
    DB *sql.DB
}

func NewConn() *Conn {
    // 实现数据库连接的创建逻辑
    db, err := sql.Open("mysql", "user:password@tcp(127.0.0.1:3306)/test")
    if err != nil {
        panic(err)
    }
    return &Conn{DB: db}
}

func (c *Conn) Close() {
    // 实现数据库连接的关闭逻辑
    c.DB.Close()
}

var pool sync.Pool

func main() {
    pool.New = func() interface{} {
        // 创建新的连接对象
        return NewConn()
    }
    conn := pool.Get().(*Conn)
    defer pool.Put(conn)

    // 使用数据库连接执行操作
}

Implementation of the connection pool expansion mechanism:

The key to realizing the connection pool expansion is to define a dynamic expansion condition . When the connection pool has insufficient free connections, we can trigger expansion by checking the number of connections in the connection pool when acquiring connections. We can add a judgment on the number of connection pool connections in the function that obtains the connection.

The following is a code example of the connection pool expansion mechanism:

package main

import (
    "database/sql"
    "sync"
)

const (
    MaxConnections = 100 // 最大连接数
    IdleThreshold  = 10  // 空闲连接数的阈值，小于该值时触发扩容
)

type Conn struct {
    DB *sql.DB
}

func NewConn() *Conn {
    db, err := sql.Open("mysql", "user:password@tcp(127.0.0.1:3306)/test")
    if err != nil {
        panic(err)
    }
    return &Conn{DB: db}
}

func (c *Conn) Close() {
    c.DB.Close()
}

var pool sync.Pool
var connCount int // 当前连接数

func init() {
    pool.New = func() interface{} {
        return NewConn()
    }
}

func GetConn() *sql.DB {
    // 检查空闲连接数
    if connCount < IdleThreshold {
        expandPool()
    }

    conn := pool.Get().(*Conn)
    return conn.DB
}

func PutConn(db *sql.DB) {
    conn := &Conn{DB: db}
    pool.Put(conn)
}

func expandPool() {
    for i := 0; i < MaxConnections/10; i++ {
        conn := NewConn()
        pool.Put(conn)
        connCount++
    }
}

func main() {
    // 使用连接池的连接进行数据库操作
    db := GetConn()
    defer PutConn(db)
}

In the above code, we use connCount to record the number of connections in the current connection pool. When the number of connections is less than IdleThreshold, trigger Expansion. The expandPool function expands according to the setting of MaxConnections, expanding the number of connections by 10% each time.

Summary:

The above is a specific code example to solve the problem of connection pool expansion of concurrent database connections in Go language. Through reasonable connection pool design and expansion mechanism, we can improve the efficiency and performance of database connections in concurrent scenarios. Of course, the specific implementation needs to be adjusted and optimized according to the actual situation to meet business needs.

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