通过一个线程获取作业，但并行执行多个线程的作业

Question

我从数据库中获取作业。我想从DB获取记录是单线程的。一旦我完成了所有工作，我希望它们可以并行执行多个线程。

Answer 1

正如你所说，你正在使用Spring，我建议你查一下their documentation。

然后，您可以让您的线程查询数据库将您的工作（包含在Callable或Runnable中）提交到ThreadPoolTaskExecutor。

Answer 2

1. 首先从数据库中提取记录以进行处理。
2. 我正在与客户分组记录。

3. 我正在将每个客户的处理传递给线程池。

   .....
   @Autowired
   ThreadPoolTaskExecutor taskExecutor;
   
   @Autowired
   private ApplicationContext applicationContext;
   
   @Transactional
   public void processPendingPayments() {
       logger.debug("ProcessPendingPayments.processPendingPayments begins");
       logger.info("startTime::" + System.currentTimeMillis());
       List<PaymentRequestEntity> recordsPendingForPayment = getRecordsPendingForPayment();
   
       // Group Requests with Customers
       Map<String, List<PaymentRequestEntity>> customerPaymentRequestsMap = getPendingRecordsGroupedByCustomer(
               recordsPendingForPayment);
   
       // process Payment requests for customers
       for (String customerId : customerPaymentRequestsMap.keySet()) {
   
           CustomerPaymentRequestProcessor customerPaymentRequestProcessor = (CustomerPaymentRequestProcessor) applicationContext
                   .getBean("customerPaymentRequestProcessor");
           customerPaymentRequestProcessor.setStrCustomerId(customerId);
           customerPaymentRequestProcessor.setCustomerPaymentRequestsMap(customerPaymentRequestsMap);
           taskExecutor.execute(customerPaymentRequestProcessor);
   
       }
       logger.info("endTime::" + System.currentTimeMillis());
       logger.debug("ProcessPendingPayments.processPendingPayments ends");
   }
   ........
   

   以下是Runnable类的代码，用于处理每个客户的记录

   @Component
   @Scope("prototype")
   public class CustomerPaymentRequestProcessor implements Runnable {
   
       private static final Logger logger = LoggerFactory.getLogger(CustomerPaymentRequestProcessor.class);
   
       private String strCustomerId;
   
       private Map<String, List<PaymentRequestEntity>> customerPaymentRequestsMap;
   
       private final String REQUEST_TYPE_BALANCE = "Balance";
   
       @Autowired
       private BalanceServiceImpl balanceServiceImpl;
   
       @Autowired
       PendingPaymentsSequenceProcessor pendingPaymentsSequenceProcessor;
   
       @Autowired
       CustomerAuditServiceImpl customerAuditServiceImpl;
   
       public CustomerPaymentRequestProcessor() {
   
       }
   
       public CustomerPaymentRequestProcessor(String strCustomerId,
               Map<String, List<PaymentRequestEntity>> customerPaymentRequestsMap) {
           super();
           this.strCustomerId = strCustomerId;
           this.customerPaymentRequestsMap = customerPaymentRequestsMap;
       }
   
       @Override
       public void run() {
           logger.debug("CustomerPaymentRequestProcessor.run starts");
           List<PaymentRequestEntity> paymentRequests = getCustomerPaymentRequestsMap().get(getStrCustomerId());
           for (PaymentRequestEntity paymentRequest : paymentRequests) {
   
               CustomerBalanceResponse customerBalanceResponse = processPaymentRequest(paymentRequest);
               if (!customerBalanceResponse.isCustomerHasBalance()
                       && REQUEST_TYPE_BALANCE.equals(paymentRequest.getRequestType())) {
                   break;
               }
   
           }
           logger.debug("CustomerPaymentRequestProcessor.run ends");
       }
       ....
       ....
       }