- <?php
- $conn=mysql_connect("localhost","big","123456");
- if(!$conn){
- echo "connect failed";
- exit;
- }
- mysql_select_db("big",$conn);
- mysql_query("set names utf8");
- $price=10;
- $user_id=1;
- $goods_id=1;
- $sku_id=11;
- $number=1;
- //生成唯一訂單號
- function build_order_no(){
- return date('ymd').substr(implode(NULL, array_map('ord', str_split(substr(uniqid(), 7, 13), 1))), 0, 8);
- }
- //記錄日誌
- function insertLog($event,$type=0){
- global $conn;
- $sql="insert into ih_log(event,type)
- values('$event','$type')";
- mysql_query($sql,$conn);
- }
- //模擬下單操作
- //庫存是否大於0
- mysql_query("BEGIN"); //開始事務
- $sql="select number from ih_store where goods_id='$goods_id' and sku_id='$sku_id' FOR UPDATE";//此時這條記錄被鎖住,其它事務必須等待此次事務提交後才能執行
- $rs=mysql_query($sql,$conn);
- $row=mysql_fetch_assoc($rs);
- if($row['number']>0){
- //生成訂單
- $order_sn=build_order_no();
- $sql="insert into ih_order(order_sn,user_id,goods_id,sku_id,price)
- values('$order_sn','$user_id','$goods_id','$sku_id','$price')";
- $order_rs=mysql_query($sql,$conn);
- //庫存減少
- $sql="update ih_store set number=number-{$number} where sku_id='$sku_id'";
- $store_rs=mysql_query($sql,$conn);
- if(mysql_affected_rows()){
- insertLog('庫存減少成功');
- mysql_query("COMMIT");//事務提交即解鎖
- }else{
- insertLog('庫存減少失敗');
- }
- }else{
- insertLog('庫存不夠');
- mysql_query("ROLLBACK");
- }
- ?>
優化方案3:使用非阻塞的文件排他鎖
- <?php
- $conn=mysql_connect("localhost","root","123456");
- if(!$conn){
- echo "connect failed";
- exit;
- }
- mysql_select_db("big-bak",$conn);
- mysql_query("set names utf8");
- $price=10;
- $user_id=1;
- $goods_id=1;
- $sku_id=11;
- $number=1;
- //生成唯一訂單號
- function build_order_no(){
- return date('ymd').substr(implode(NULL, array_map('ord', str_split(substr(uniqid(), 7, 13), 1))), 0, 8);
- }
- //記錄日誌
- function insertLog($event,$type=0){
- global $conn;
- $sql="insert into ih_log(event,type)
- values('$event','$type')";
- mysql_query($sql,$conn);
- }
- $fp = fopen("lock.txt", "w+");
- if(!flock($fp,LOCK_EX | LOCK_NB)){
- echo "系統繁忙,請稍後再試";
- return;
- }
- //下單
- $sql="select number from ih_store where goods_id='$goods_id' and sku_id='$sku_id'";
- $rs=mysql_query($sql,$conn);
- $row=mysql_fetch_assoc($rs);
- if($row['number']>0){//庫存是否大於0
- //模擬下單操作
- $order_sn=build_order_no();
- $sql="insert into ih_order(order_sn,user_id,goods_id,sku_id,price)
- values('$order_sn','$user_id','$goods_id','$sku_id','$price')";
- $order_rs=mysql_query($sql,$conn);
- //庫存減少
- $sql="update ih_store set number=number-{$number} where sku_id='$sku_id'";
- $store_rs=mysql_query($sql,$conn);
- if(mysql_affected_rows()){
- insertLog('庫存減少成功');
- flock($fp,LOCK_UN);//釋放鎖
- }else{
- insertLog('庫存減少失敗');
- }
- }else{
- insertLog('庫存不夠');
- }
- fclose($fp);
優化方案4:使用redis隊列,因爲pop操作是原子的,即使有很多用戶同時到達,也是依次執行,推薦使用(mysql事務在高併發下性能下降很厲害,文件鎖的方式也是)
先將商品庫存如隊列
- <?php
- $store=1000;
- $redis=new Redis();
- $result=$redis->connect('127.0.0.1',6379);
- $res=$redis->llen('goods_store');
- echo $res;
- $count=$store-$res;
- for($i=0;$i<$count;$i++){
- $redis->lpush('goods_store',1);
- }
- echo $redis->llen('goods_store');
- ?>
搶購、描述邏輯
- <?php
- $conn=mysql_connect("localhost","big","123456");
- if(!$conn){
- echo "connect failed";
- exit;
- }
- mysql_select_db("big",$conn);
- mysql_query("set names utf8");
- $price=10;
- $user_id=1;
- $goods_id=1;
- $sku_id=11;
- $number=1;
- //生成唯一訂單號
- function build_order_no(){
- return date('ymd').substr(implode(NULL, array_map('ord', str_split(substr(uniqid(), 7, 13), 1))), 0, 8);
- }
- //記錄日誌
- function insertLog($event,$type=0){
- global $conn;
- $sql="insert into ih_log(event,type)
- values('$event','$type')";
- mysql_query($sql,$conn);
- }
- //模擬下單操作
- //下單前判斷redis隊列庫存量
- $redis=new Redis();
- $result=$redis->connect('127.0.0.1',6379);
- $count=$redis->lpop('goods_store');
- if(!$count){
- insertLog('error:no store redis');
- return;
- }
- //生成訂單
- $order_sn=build_order_no();
- $sql="insert into ih_order(order_sn,user_id,goods_id,sku_id,price)
- values('$order_sn','$user_id','$goods_id','$sku_id','$price')";
- $order_rs=mysql_query($sql,$conn);
- //庫存減少
- $sql="update ih_store set number=number-{$number} where sku_id='$sku_id'";
- $store_rs=mysql_query($sql,$conn);
- if(mysql_affected_rows()){
- insertLog('庫存減少成功');
- }else{
- insertLog('庫存減少失敗');
- }
模擬5000高併發測試
webbench -c 5000 -t 60 http://192.168.1.198/big/index.php
ab -r -n 6000 -c 5000 http://192.168.1.198/big/index.php
上述只是簡單模擬高併發下的搶購,真實場景要比這複雜很多,很多注意的地方
如搶購頁面做成靜態的,通過ajax調用接口
再如上面的會導致一個用戶搶多個,思路:
需要一個排隊隊列和搶購結果隊列及庫存隊列。高併發情況,先將用戶進入排隊隊列,用一個線程循環處理從排隊隊列取出一個用戶,判斷用戶是否已在搶購結果隊列,如果在,則已搶購,否則未搶購,庫存減1,寫數據庫,將用戶入結果隊列。
測試數據表
- --
- -- 數據庫: `big`
- --
- -- --------------------------------------------------------
- --
- -- 表的結構 `ih_goods`
- --
- CREATE TABLE IF NOT EXISTS `ih_goods` (
- `goods_id` int(10) unsigned NOT NULL AUTO_INCREMENT,
- `cat_id` int(11) NOT NULL,
- `goods_name` varchar(255) NOT NULL,
- PRIMARY KEY (`goods_id`)
- ) ENGINE=MyISAM DEFAULT CHARSET=utf8 AUTO_INCREMENT=2 ;
- --
- -- 轉存表中的數據 `ih_goods`
- --
- INSERT INTO `ih_goods` (`goods_id`, `cat_id`, `goods_name`) VALUES
- (1, 0, '小米手機');
- -- --------------------------------------------------------
- --
- -- 表的結構 `ih_log`
- --
- CREATE TABLE IF NOT EXISTS `ih_log` (
- `id` int(11) NOT NULL AUTO_INCREMENT,
- `event` varchar(255) NOT NULL,
- `type` tinyint(4) NOT NULL DEFAULT '0',
- `addtime` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
- PRIMARY KEY (`id`)
- ) ENGINE=MyISAM DEFAULT CHARSET=utf8 AUTO_INCREMENT=1 ;
- --
- -- 轉存表中的數據 `ih_log`
- --
- -- --------------------------------------------------------
- --
- -- 表的結構 `ih_order`
- --
- CREATE TABLE IF NOT EXISTS `ih_order` (
- `id` int(11) NOT NULL AUTO_INCREMENT,
- `order_sn` char(32) NOT NULL,
- `user_id` int(11) NOT NULL,
- `status` int(11) NOT NULL DEFAULT '0',
- `goods_id` int(11) NOT NULL DEFAULT '0',
- `sku_id` int(11) NOT NULL DEFAULT '0',
- `price` float NOT NULL,
- `addtime` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
- PRIMARY KEY (`id`)
- ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT='訂單表' AUTO_INCREMENT=1 ;
- --
- -- 轉存表中的數據 `ih_order`
- --
- -- --------------------------------------------------------
- --
- -- 表的結構 `ih_store`
- --
- CREATE TABLE IF NOT EXISTS `ih_store` (
- `id` int(11) NOT NULL AUTO_INCREMENT,
- `goods_id` int(11) NOT NULL,
- `sku_id` int(10) unsigned NOT NULL DEFAULT '0',
- `number` int(10) NOT NULL DEFAULT '0',
- `freez` int(11) NOT NULL DEFAULT '0' COMMENT '虛擬庫存',
- PRIMARY KEY (`id`)
- ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT='庫存' AUTO_INCREMENT=2 ;
- --
- -- 轉存表中的數據 `ih_store`
- --
- INSERT INTO `ih_store` (`id`, `goods_id`, `sku_id`, `number`, `freez`) VALUES
- (1, 1, 11, 500, 0);