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SecKillProject

Backend Restful API simulates handling high concurrent QPS by using multithreading and caching

Project Status

Under maintain

  • Completed: User management
  • Completed: Order service (single thread)
  • Completed: Implemented Redis caching
  • Completed: Implemented multi-thread to handle high incoming queries

Tech Stack

  • Springboot + Redis + MySQL
  • JMeter

Handling High Concurrent Incoming Queries

  • Using @Async and ThreadPoolTaskExecutor to complete background tasks asynchronously.
  • Using Redis caching to prevent high IO pressure for MySQL database.
  • Using Synchronize() keyword to ensure thread-safety.
  • Using Jmeter to simulate concurrent queries.

JMeter Testing

  • Setting for concurrent queries (1000 users) alt text
  • HTTP request to api alt text
  • Merchandise stock counts (Only 10 stock available) alt text
  • Issue: oversold alt text

  • Analyze: Since tasks are running under multiple threads, we need to guarantee that stock=stock-1 is atomic
Merchandise item = (Merchandise) redisTemplate.boundHashOps(Merchandise.class.getSimpleName()).get(Integer.toString(orderRecord.getMerchandise_id()));
                if(item != null){
                    if(item.getMerchandise_stock()>0){
                        item.setMerchandise_stock(item.getMerchandise_stock() - 1); //NOT ATMOIC STATEMENT
                        redisTemplate.boundHashOps(Merchandise.class.getSimpleName()).put(Integer.toString(item.getMerchandise_id()), item);
                        redisTemplate.boundHashOps(OrderInfo.class.getSimpleName()).put(LocalTime.now()+Integer.toString(orderRecord.getUser_id()), orderInfo);

                    }
                }
  • Solution: Using synchronize keyword to ensure the block of code is executed all in one.
synchronized (OrderThread.class) {
                Merchandise item = (Merchandise) redisTemplate.boundHashOps(Merchandise.class.getSimpleName()).get(Integer.toString(orderRecord.getMerchandise_id()));
                if(item != null){
                    if(item.getMerchandise_stock()>0){
                        item.setMerchandise_stock(item.getMerchandise_stock() - 1);
                        redisTemplate.boundHashOps(Merchandise.class.getSimpleName()).put(Integer.toString(item.getMerchandise_id()), item);
                        redisTemplate.boundHashOps(OrderInfo.class.getSimpleName()).put(LocalTime.now()+Integer.toString(orderRecord.getUser_id()), orderInfo);

                    }
                }
            }
  • Only 10 items are sold alt text

  • Other possible solution: Using optimistic locking, ex: CAS with version

Setup MySQL and Redis

Install MySQL and Redis
Locate application.properties

spring.datasource.url= {MYSQL connection url}
spring.datasource.username= {Username}
spring.datasource.password= {Password}
spring.redis.host=127.0.0.1
spring.redis.port={port}
redis.config.host=redis://127.0.0.1:{port}

API Usage

See comments in src/main/java/com.learning.SecKillProject/SecKillProject.java