Multi-threading scheme to ensure that a single thread opens a transaction and takes effect

When we develop, we often encounter the problem of multi-threaded transactions.I thought it was enough to add the @Transactional annotation. In fact, after you added the annotation, you will find that the transaction is invalid.Reason: The database connection spring is placed in threadLocal. In multi-threaded scenarios, the database connections obtained are different, that is, they belong to different transactions.

Spring supports programmatic transactions and declarative transactions. The most primitive transaction management method provided by Spring is based on TransactionDefinition, PlatformTransactionManager, and TransactionStatus programmatic transactions.
The transaction management of TransactionTemplate is the encapsulation of the original transaction management method using the template method design pattern, so we can also use TransactionTemplate to manage transactions.

Today, let's talk about the solution for a single thread to start a transaction:

1. Propose the thread method directly and add the @Transactional annotation

// Method to enable multithreadingpublic void testTransactional() throws ExecutionException, InterruptedException {int inter = 3;ExecutorService executorService = Executors.newFixedThreadPool(inter);ThreadPoolExecutor poolExecutor = (ThreadPoolExecutor) executorService;FutureTask[] integerFuture = new FutureTask[inter];for (int i = 0; i < inter; i++) {int finalI = i + 1;integerFuture[i] = new FutureTask<>(() -> {testTransactionalServiceZi.testTransactionalZi(finalI, "calculation" + finalI);System.out.println("Multiple threads are running---" + finalI);return "Business execution succeeded";});poolExecutor.execute(integerFuture[i]);}for (int i = 0; i < inter; i++) {System.out.println("integerFuture return result = " + i + "==" + integerFuture[i].get());}}// single thread call, add [email protected] void testTransactionalZi(int num, String str) {// modify data ===1===AdCourse adCourse = new AdCourse();adCourse.setId(num);adCourse.setName(str);int i = adCourseMapper.updateById(adCourse);// modify data ===2===adCourse.setId(num + 3);adCourse.setName(str + 0);int result = adCourseMapper.updateById(adCourse);// Manually create an exception (the transaction will take effect)result = 1/0;}

2. Use TransactionTemplate to manage transactions

By interpreting the source code, TransactionTemplate encapsulates PlatformTransactionManager.It is more troublesome for us to write PlatformTransactionManager by ourselves to manage transactions, so we use TransactionTemplate to display the code, as follows:

@Servicepublic class TestTransactionalServiceImpl implements TestTransactionalService {@Autowiredprivate TestTransactionalServiceZi testTransactionalServiceZi;// Use Template to control [email protected] TransactionTemplate template;public void testTransactional() throws ExecutionException, InterruptedException {int inter = 3;ExecutorService executorService = Executors.newFixedThreadPool(inter);ThreadPoolExecutor poolExecutor = (ThreadPoolExecutor) executorService;FutureTask[] integerFuture = new FutureTask[inter];for (int i = 0; i < inter; i++) {int finalI = i + 1;integerFuture[i] = new FutureTask<>(() -> {return template.execute(new TransactionCallback() {@Overridepublic String doInTransaction(TransactionStatus transactionStatus) {testTransactionalServiceZi.testTransactionalZi(finalI, "Calculate 666" + finalI);System.out.println("Multiple threads are running---" + finalI);return "Business execution succeeded";}});});poolExecutor.execute(integerFuture[i]);}for (int i = 0; i < inter; i++) {System.out.println("integerFuture return result = " + i + "==" + integerFuture[i].get());}}}// method to callpublic void testTransactionalZi(int num, String str) {// modify data ===1===AdCourse adCourse = new AdCourse();adCourse.setId(num);adCourse.setName(str);int i = adCourseMapper.updateById(adCourse);// modify data ===2===adCourse.setId(num + 3);adCourse.setName(str + 0);int result = adCourseMapper.updateById(adCourse);// Manually create an exception (the transaction will take effect)result = 1/(num-1);}

Print result: The first thread did not execute successfully, an exception occurred, and the data did not change.

Summary: The above two methods can guarantee the problem of single thread transaction in multithreading