如何在列表中并行操作潜在的数据库交互

Question

我试图使我的代码更有效地工作，因此我试图了解如何使其与Futures和ForkJoinPool一起工作。

现在我有这样的代码：

@RestController
@RequestMapping(SEND)
@Slf4j
public class InputMessageController {
private HandlerService service;
    @ApiResponses(value = {
            @ApiResponse(code = 200, message = "message sent"),
            @ApiResponse(code = 404, message = "channel not found or inactive"),
    })
    @RequestMapping(value = "/{channel}", method = RequestMethod.POST)
    @ResponseStatus(HttpStatus.OK)
    public List<ResponseDto> sendNotification(
            @Valid @RequestBody @NotNull List<PayloadInfoDto> requestDtoList,
            @PathVariable("channel") String url) throws InputChannelInactiveException {

        InputChannel channel = mapService.getChannelByUrl(url);

        if (channel != null){
            return service.processing(requestDtoList, channel);
        } else {
            loggerService.logChannelNotFound()
            throw new InputChannelInactiveException(url);
        }
    }
}

public class HandlerServiceImpl implements HandlerService {
public List<ResponseDto> processing(List<PayloadInfoDto> requestDtoList, InputChannel channel) {

        List<ResponseDto> responseDtoList = new ArrayList<>();

//this one takes quite long. would be better if it was done in multiple threads
        requestDtoList.forEach(inputRequestDto -> responseDtoList.add(processNorm(inputRequestDto, channel)));

        return responseDtoList;
    }
}

processNorm(PayloadInfoDto inputRequestDto, InputChannel channel) {
        RequestMessage msg;

        //call to multiple services which can throw an exception. Each exception is processed.
        //call to logger service which logs info to database

}

我的问题是：

1. 对于使用数据库运行的logger服务，写操作是否比定期保存到db更好，特别是当我们不想等待db写操作并想继续时

private ExecutorService executor = Executors.newWorkStealingPool();
///....some code
public void exampleAsyncLog(){
//I don't wan't to wait while logger service writes to DB. It can take as long as it wants to write, 
//while I'll move on
executor.submit(() -> saveSomethingToDb()); //saveSomethingToDb() is trivial logRepository.save(newEntity)
}

Answer 1

我会建议您使用CompletableFuture来完成此任务，因为您只希望在所有任务都保存在DB中时才能继续，这对您的任务来说是最安全的。因此，编写如下代码：

public class HandlerServiceImpl implements HandlerService {
public List<ResponseDto> processing(List<PayloadInfoDto> requestDtoList, InputChannel channel) {

        List<ResponseDto> responseDtoList = new ArrayList<>();

//this one takes quite long. would be better if it was done in multiple threads
CompletableFuture<List<ResponseDto>> future
  = CompletableFuture.supplyAsync(() -> requestDtoList.stream().map(inputRequestDto -> processNorm(inputRequestDto, channel)).collect(Collectors.toList())); //This code is not tested. It's the logic that I am showing you to implement that will work for you.

        return future.get();//wait till all the operation is completed.
    }
}