Redis (II) distributed locks and redis cluster construction

One 、 Thread lock and distributed lock

• Thread lock Single project

  • Single project

    • step

      • The code is as follows

         // Define static global locks 
         private readonly static object _lock = new object();
        //  Add code to the controller 
          lock (_lock)
          { 
            Stock sto = new Stock();
            sto = demoDbContext.stock.Where(p => p.ID == 1).FirstOrDefault();
            if (sto.count == 0)
            {
                Console.WriteLine(Thread.CurrentThread.ManagedThreadId + "--- End of seckill , No stock ");
                return Ok(" End of seckill , No stock ");
             }
              Console.WriteLine(Thread.CurrentThread.ManagedThreadId + "-- Seckill success ;");
              // Inventory decrease 1
              sto.count = sto.count - 1;
              demoDbContext.SaveChanges();
          }
          return Ok(" End of seckill ");
        

    • The number of databases is 10
      Pictured ：
      

    • use jmeter Concurrent 10 Threads
      Pictured ：
      

    • The operation results are as follows ：
      

• Distributed lock

  • Conditions

    • Start two instances 5000/5001
    • Nginx
    • jmeter
    • redis

  • step

    • Core code

            public class RedisLock
            {
                public readonly ConnectionMultiplexer connectionMultiplexer;
                private IDatabase database = null; 
                public RedisLock() 
                {
                    connectionMultiplexer = ConnectionMultiplexer.Connect("127.0.0.1:6380");
                    database = connectionMultiplexer.GetDatabase(0);
                }
              
                /// <summary>
                ///  Lock 
                /// </summary>
                public void Lock() 
                { 
                    while (true) //
                    {   
                        //redis_lock  Lock name 
                        // Thread.CurrentThread.ManagedThreadId  Thread name 
                        // TimeSpan.FromSeconds(10)   Set expiration time    Prevent deadlock 
                        bool flag = database.LockTake("redis_lock", Thread.CurrentThread.ManagedThreadId, TimeSpan.FromSeconds(10));
                        //true ： Locking success   false： Locking failed 
                        if (flag) 
                        {
                            break;
                        }
                        Thread.Sleep(10);// Prevent deadlock    Waiting time    Release resources .
                    }
                }
                /// <summary>
                ///  Release the lock 
                /// </summary>
                public void UnLock() 
                {
                    database.LockRelease("redis_lock", Thread.CurrentThread.ManagedThreadId);
                    connectionMultiplexer.Close();
                }
            }  
      

      Used in the controller

       [HttpGet]
        [Route("SubStock")]
        public IActionResult SubStock()
        {
      
            RedisLock redisLock = new RedisLock();
            redisLock.Lock();
            Stock sto = new Stock();
            sto = demoDbContext.stock.Where(p => p.ID == 1).FirstOrDefault();
            if (sto.count == 0)
            {
                Console.WriteLine(Thread.CurrentThread.ManagedThreadId + "--- End of seckill , No stock ");
                //redisLock.UnLock();
                return Ok(" End of seckill , No stock ");
            }
            Console.WriteLine(Thread.CurrentThread.ManagedThreadId + "-- Seckill success ;");
            // Inventory decrease 1
            sto.count = sto.count - 1;
            demoDbContext.SaveChanges();
            redisLock.UnLock();
      
            return Ok(" End of seckill ");
        }
      

    • Run two instances
      Pictured ：
      
      

    • start-up Nginx
      Pictured ：
      

    • Database inventory
      Pictured ：
      

    • jmeter Concurrent 10 Threads
      

    • The operation results are as follows
      

  • The usage scenarios of distributed lock
    When modifying a field value in the cluster system, a distributed lock is used .

  • The design idea of distributed lock
    For example, two processes are concurrent , When the first process is locked , The second process will fail to lock , Will sleep （10 millisecond ）, Until the first process executes the business code and releases the lock , If the first process processes business code more than 10 millisecond ,redis The expiration time of is also 10 millisecond , Then the second process locks, executes the business code and releases the lock .
    remarks ： The number of milliseconds to sleep can be defined according to your own business code , The number of milliseconds should be the same as redis The expiration time is the same .

Two 、Redis colony

• First generation cluster Master-slave cluster

  • Pictured ：
    

  • shortcoming
    only one master, When maset After downtime , Whole redis The clustered system cannot be used .

• Second generation clusters The sentry cluster

  • Pictured
    

    The second generation cluster is one more than the first generation cluster sentinel The role of monitoring , When the primary node goes down ,sentinel A master node will be selected from multiple slave nodes .

  • shortcoming

    • only one master, Can't solve the problem of high concurrent write .
    • Can't store massive data .
• Third generation cluster

  • Pictured ：
    

  • Advantages and disadvantages

    • advantage
      • Solve the problem of high concurrent write .
      • Storing massive amounts of data .
    • shortcoming
      • It consumes a lot of resources .

  • Realization

    • Conditions
      • windows Environmental Science
      • Redis
        • Download address of online disk
          link ：https://pan.baidu.com/s/1-rdemcSLHHFSy3b03EnQsg
          Extraction code ：liiz
      • Ruby
        • Download address of online disk
          link ：https://pan.baidu.com/s/1NEnVoZzzMyROdm0qNeqw0g
          Extraction code ：lf10
      • Ruby drive
        • Download address of online disk
          link ：https://pan.baidu.com/s/1LkpTstTMenespCx4J0ZtWA
          Extraction code ：7wn6
      • Assign master-slave tools
        • Download address of online disk
          link ：https://pan.baidu.com/s/18ah0ePiGr9XCukRsRdIiXw
          Extraction code ：0e02

  • step

    • Configure the cluster file （6 An example ） To configure 6 Configuration files 【 And will 6 Copy configuration to redis The root directory 】 The configuration cannot have Chinese comments ！！！！

        port 6380                                         # port 
        bind 127.0.0.1                                    #IP Address 
        appendonly yes                                    # The data storage format is aof
        appendfilename "appendonly.6380.aof"              # Data saving file 
        cluster-enabled yes                               # Do you want to open the cluster 
        cluster-config-file nodes.6380.conf               # Cluster node configuration file 
        cluster-node-timeout 15000                        # Node timeout 
        cluster-slave-validity-factor 10                  # verification slaver Number of nodes 
        cluster-migration-barrier 1                       #
        cluster-require-full-coverage yes                 #master Nodes and slaver Whether the nodes are fully replicated 
      

    • Execute all instances

      redis-server.exe redis.6380.conf 
      redis-server.exe redis.6381.conf 
      redis-server.exe redis.6382.conf 
      redis-server.exe redis.6383.conf 
      redis-server.exe redis.6384.conf 
      redis-server.exe redis.6385.conf 
      

      Pictured ：
      
      
      
      
      
      

    • install ruby

        ruby --version # Verify that the installation was successful 
      

    • redis-cluster Drive installation command

        # Get into  ruby The installation directory bin Execute the installation command under the file 
        ruby gem install --local  D:\Assembly\redis\Windows\redis-cluster\redis-3.2.2.gem  # Drive file path 
      

    • Execute the script for assigning master-slave tools

      ruby redis-trib.rb create --replicas 1  127.0.0.1:6380  127.0.0.1:6381 127.0.0.1:6382   127.0.0.1:6383  127.0.0.1:6384  127.0.0.1:6385 
      # Write all instance addresses and port numbers 
      # --replicas 1： Whether to allocate 3 Lord 3 from   A master node and a slave node  
      

      Pictured ：
      

    • Check whether the assignment is successful
      When 6 An instance keeps outputting logs , Indicates that the assignment has been successful .

  • redis Cluster internal relationship structure diagram
    Pictured ：
    

    stay redis In the cluster , Each node communicates with each other , The protocol used is Gossip agreement .

  • redis The principle of data storage in the cluster

    • Slot Slot The primary node has slots [ Average distribution ] Slave node has no slot All in all 16384 Slot

        ruby redis-trib.rb check 127.0.0.1:6380 
      

    • Hash Algorithm
    • Modular algorithm
      When the client writes data to the node , The node will key Use hash The algorithm takes a fixed length value , Then the total number of slots 【16384】 Take the module with the module taking algorithm , After the value is obtained, go to each master node to check the value between the number of slots of which node , When writing data to that master node .