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限制单位时间内执行次数，并保持先后顺序。

package main

import "fmt"
import "time"

var c chan chan int

func worker(i int) {
        t := make(chan int)
        c <- t
        fmt.Println(i, "启动任务")
loop:
        for {
                select {
                case <-t:
                        fmt.Println(i)
                        break loop
                default:
                        fmt.Println(i, "等待可用")
                        time.Sleep(100 * time.Millisecond)
                }
        }

        fmt.Println(i, "开始任务")
}
func master() {
        for {
                for i := 0; i < 10; i++ {
                        t := <-c
                        t <- 1
                        time.Sleep(500 * time.Millisecond)
                }
        }
}

func main() {
        c = make(chan chan int, 20)
        for i := 0; i < 10; i++ {
                go worker(i)
                time.Sleep(500 * time.Millisecond)
        }
        go master()
        for {
                time.Sleep(1000 * time.Millisecond)

        }
}

新建：

pvcreate /dev/vd[b-c]1
vgcreate alivg /dev/vd[b-c]1
lvcreate -l +100%free -i 2 -I 128 alivg -n alilv
mkfs.ext4 /dev/alivg/alilv 
mount /dev/alivg/alilv /data/

查看lv信息：

lvdisplay -m
  --- Segments ---
  Logical extents 0 to 10237:
    Type        striped
    Stripes        2
    Stripe size        512.00 KiB
    Stripe 0:
      Physical volume    /dev/vdb1
      Physical extents    0 to 5118
    Stripe 1:
      Physical volume    /dev/vdc1
      Physical extents    0 to 5118

扩充：

pvcreate /dev/vd[d-e]1
vgextend alivg /dev/vd[d-e]1
lvresize -l +100%free -i 2 -I 128 /dev/alivg/alilv
resize2fs /dev/alivg/alilv

使用dd测试吞吐量：

#默认启用写缓存
dd bs=64k count=4k if=/dev/zero of=test;rm -rf test
#最后一次性写入硬盘
dd bs=64k count=4k if=/dev/zero of=test conv=fdatasync;rm -rf test
#每次读取64k马上写入硬盘
dd if=/dev/zero of=test bs=64k count=4k oflag=dsync;rm -rf test

使用测试读吞吐量：

hdparm -Tt /dev/vdc1

使用fio测试iops和吞吐量：

fio --bs=4k --ioengine=libaio --iodepth=1 --direct=1 --rw=read --time_based --runtime=600  --refill_buffers --norandommap --randrepeat=0 --group_reporting --name=fio-read --size=100G --filename=/dev/sdb

block=4k iodepth=1 随机读测试，能反映磁盘的时延性能；
block=128K iodepth=32 能反映峰值吞吐性能 ;
block=4k iodepth=32 能反映峰值IOPS性能。

随机读写iops：

吞吐量：

延时：

参考：
https://www.qcloud.com/document/product/362/6741
https://www.qcloud.com/document/product/362/6745

package main
import (
        "fmt"
    "database/sql"
    _ "github.com/go-sql-driver/mysql"
)

func main() {
    var sqlt string
    var table string
    db, err := sql.Open("mysql", "root:password@/dbname?charset=utf8")
    //查询
    sqlt = "SELECT tid from " + table + " where id = (SELECT max(id) FROM " + table + ");"
    rows, err = db.Query(sqlt)
    for rows.Next() {
        err = rows.Scan(&tid)
        fmt.Println(tid)
    }

    //插入
    sqlt = "INSERT " + table + " SET tid=?,amount=?,price=?,time=?,type=?,funds=?"
    stmt, _ := db.Prepare(sqlt)
    stmt.Exec(v.Id, v.Volume, v.Price, v.At, v.Side, v.Funds)
    //执行
    db.Exec("delete from table where id = '1'")
}

$dsn = "mysql:host=localhost;dbname=dbname";
$pdo = new PDO($dsn,"userpassword","password");
//查询
$sql = "SELECT * from tables where id > 1 limit 1";
$row = $pdo->query($sql);
$row = $row->fetchAll(PDO::FETCH_ASSOC);

//插入
$sql = "insert into table(tid,price) values(:tid, :price)";
$stmt = $pdo->prepare($sql);
$stmt->execute(array('35678', '100'));

//删除
$dbh->exec("delete from table where id = '1'");