英文:
How to solve TIME_WAIT state issue when in multiple concurrency?
问题
如果我在Windows上运行下面的示例，我会很快达到TCP连接限制（我将其设置为64k），并收到错误消息：dial tcp 127.0.0.1:3306: connectex: Only one usage of each socket address (protocol/network address/port) is normally permitted.
我通过使用netstat -ano|findstr 3306命令看到了所有这些处于TIME_WAIT状态的连接。
为什么连接不会立即关闭？
代码如下：
package main
import (
_ "github.com/go-sql-driver/mysql"
"github.com/jmoiron/sqlx"
"log"
"sync"
)
var (
db_instance *sqlx.DB
wg sync.WaitGroup
)
func main() {
db, err := sqlx.Connect("mysql", "user:pass@/table")
if err != nil {
log.Fatalln(err)
}
defer db.Close()
db_instance = db
for {
for l := 0; l < 50; l++ {
wg.Add(1)
go DB_TEST()
}
wg.Wait()
}
}
func DB_TEST() {
defer wg.Done()
var s string
err := db_instance.QueryRow("SELECT NOW()").Scan(&s)
if err != nil {
log.Println(err)
return
}
log.Println(s)
}
英文:
If I run below example on Windows I will quickly hit TCP connection limit (which I set to 64k) and get error: dial tcp 127.0.0.1:3306: connectex: Only one usage of each socket address (protocol/network address/port) is normally permitted.
I see all this TIME_WAIT states waiting for there lifetime to end with: netstat -ano|findstr 3306
Why aren't connections closed immediately?
The code:
package main
import (
_ "github.com/go-sql-driver/mysql"
"github.com/jmoiron/sqlx"
"log"
"sync"
)
var (
db_instance *sqlx.DB
wg sync.WaitGroup
)
func main() {
db, err := sqlx.Connect("mysql", "user:pass@/table")
if err != nil {
log.Fatalln(err)
}
defer db.Close()
db_instance = db
for {
for l := 0; l < 50; l++ {
wg.Add(1)
go DB_TEST()
}
wg.Wait()
}
}
func DB_TEST() {
defer wg.Done()
var s string
err := db_instance.QueryRow("SELECT NOW()").Scan(&s)
if err != nil {
log.Println(err)
return
}
log.Println(s)
}
答案1
得分: 1
利用SetMaxOpenConns和SetMaxIdleConns设置来控制TIME_WAIT状态和连接。如果需要，也可以使用SetConnMaxLifetime，但通常不需要。
英文:
Drafting answer from my comments discussion with @Glavić.
Utilize the SetMaxOpenConns and SetMaxIdleConns settings to keep TIME_WAIT status and connections under control. If needed use SetConnMaxLifetime too, generally it's not needed.
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