Asynchronous Controller in Spring Boot - rest

Question

I have created Webservice using Spring boot and in this there is a rest controller which hits the database via vendor based JDBC driver and fetch the records. In this process number of records retrieved are more than 80K records. Due to this when ever we are hitting the the rest endpoint as client , we are getting time out errors.
I have tried setting up the asynchronous calls using the below tutorial.But unfortunately , rest calls are still timing out.
https://howtodoinjava.com/spring-boot2/enableasync-async-controller/
Controller
#RequestMapping(value = "/v1/lr/fullpositionasync", produces = {APPLICATION_JSON_UTF8_VALUE}, method = RequestMethod.GET)
#ResponseBody
public CompletableFuture<List<Position>> retrieveTradePositionsFullAsync(HttpServletRequest request, HttpServletResponse response) throws ExecutionException, InterruptedException {
CompletableFuture<List<Position>> positionList =null;
try {
positionList = positionService.getFullPosition();
}
catch(Exception e){
log.info("Error Occurred in Controller is:"+e.getMessage());
}
CompletableFuture.allOf(positionList).join();
log.info(String.valueOf(positionList.get()));
return positionList;
}
Service
#Service
#Slf4j
public class PositionServiceImpl implements PositionService {
#Autowired
private PositionDao positionDao;
#Async("asyncExecutor")
#Override
public CompletableFuture<List<Position>> getFullPosition() {
List<Position> fullpositionList = null;
log.info("Getting the full Position process started");
fullpositionList = positionDao.retrieveData();
log.info("Total Positions retrieved:"+fullpositionList.size());
try {
log.info("Thread is about to sleep 1000 milliseconds");
Thread.sleep(1000);
}catch(InterruptedException e){
log.info(e.getMessage());
}
log.info("Full Positions retrieval completed");
return CompletableFuture.completedFuture(fullpositionList);
}
}
Configuration
#Configuration
#EnableAsync
#Slf4j
public class AsyncConfiguration
{
#Bean(name = "asyncExecutor")
public Executor asyncExecutor()
{
ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
executor.setCorePoolSize(20);
executor.setMaxPoolSize(1000);
executor.setWaitForTasksToCompleteOnShutdown(true);
executor.setThreadNamePrefix("AsynchThreadForEndPoint-");
executor.initialize();
log.info("Executor is :"+executor.toString());
return executor;
}
}
DAO
#Repository
public class PositionDaoImpl implements PositionDao {
#Autowired
private JdbcTemplate jdbcTemplate;
private static final String ALL_POSITION_QUERY = "call AllPositionProcedure()";
public List<Position> retrieveData() {
return jdbcTemplate.query(ALL_POSITION_QUERY, new BeanPropertyRowMapper(Position.class));
// List<Map<String, Object>> mapList = jdbcTemplate.queryForList(sql);
}

Answer 1

You can't perform async operations over the Database by using JDBC. JDBC is blocking, so it will block your thread until the operations will be executed. If you want to execute operations in an async manner, use R2DBC instead of JDBC.

Answer 2

For your use case, the best way to do is convert your application into Reactive Streams (Flux).
A Flux is a Reactive Streams Publisher. it is a fully non-blocking reactive programming foundation for the JVM, with efficient demand management (in the form of managing "backpressure"). It integrates directly with the Java 8 functional APIs, notably CompletableFuture, Stream, and Duration. It offers composable asynchronous sequence APIs Flux (for [N] elements) and Mono (for [0|1] elements), extensively implementing the Reactive Streams specification.
it is very simple to implement in existing app. just change your repository return type Flux instead of List or Future.
For more info, you can take reference Here