Case discovery of several implementation methods to solve concurrency problems in PHP development

This article explains case discovery of several implementation methods to solve concurrency problems in PHP development.

The examples in this article describe several implementation methods to solve concurrency problems in PHP development. Share it with everyone for your reference, the details are as follows:

In concurrent scenarios such as product rush buying, oversold phenomena may occur. At this time, these problems caused by concurrency need to be solved

There is no native concurrency solution in the PHP language, so other methods are needed to achieve concurrency control.

Option 1: Use file lock exclusive lock

Theflock function is used to obtain the file lock. This lock can only be obtained by one thread at the same time. Other threads that have not obtained the lock will either be blocked. , or the acquisition fails

When acquiring the lock, first query the inventory. If the inventory is greater than 0, place an order, reduce the inventory, and then release the lock

Option 2: Use Mysql database The pessimistic lock provided

Innodb storage engine supports row-level locking. When a row of data is locked, other processes cannot operate on the row of data

Query and lock the row first:

select stock_num from table where id=1 for update

if(stock_num > 0){

//下订单

update table set stock_num=stock-1 where id=1

}

Option 3: Use queue

to store the user’s order requests in a queue in sequence, and use a separate process in the background to process the orders in the queue Order request

Option 4: Using Redis

The operations of redis are all atomic. You can store the inventory of the product in redis. Before placing the order, perform a decr operation on the inventory. If it returns If the value is greater than or equal to 0, you can place an order, otherwise you cannot place an order. This method is more efficient.

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if(redis->get('stock_num') > 0){

stock_num = redis->decr('stock_num')

if(stock_num >= 0){

//下订单

}else{

//库存不足

}

}else{

//库存不足

}

Others Concurrency issues:

In real applications, in many cases data will be stored in the cache. When the cache fails, go to the database to retrieve the data and reset the cache. If the amount of concurrency is large at this time, there will be many processes. At the same time, it goes to the database to fetch data, resulting in many requests

penetrating into the database, causing the database to crash. File locks can be used to solve this problem

This article explains several ways to solve concurrency problems in PHP development Implementation method case discovery, please pay attention to php Chinese website for more related content.

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