用RxJava异步线程实现防止争用条件

Question

我正在使用spring framework StringRedisTemplate来更新一个与多个线程发生的条目。

public void processSubmission(final String key, final Map<String, String> submissionDTO) {
    final String hashKey = String.valueOf(Hashing.MURMUR_HASH.hash(key));
    this.stringRedisTemplate.expire(key, 60, TimeUnit.MINUTES);
    final HashOperations<String, String, String> ops = this.stringRedisTemplate.opsForHash();
    Map<String, String> data = findByKey(key);
    String json;
    if (data != null) {
        data.putAll(submissionDTO);
        json = convertSubmission(data);
    } else {
        json = convertSubmission(submissionDTO);
    }
    ops.put(key, hashKey, json);
}

key (assignmentId) -> value (submissionId, status) 

class ProcessSubmission{

@Override
    public Observable<Boolean> processSubmissionSet1(List<Submission> submissionList, HttpHeaders requestHeaders) {
        return Observable.create(observer -> {
            for (final Submission submission : submissionList) {            
                //Cache entry insert method invoke via this call
                final Boolean status = processSubmissionExecutor.processSubmission(submission, requestHeaders);
                observer.onNext(status);
            }
            observer.onCompleted();
        });
    }

    @Override
    public Observable<Boolean> processSubmissionSet2(List<Submission> submissionList, HttpHeaders requestHeaders) {
        return Observable.create(observer -> {
            for (final Submission submission : submissionList) {
                //Cache entry insert method invoke via this call
                final Boolean status = processSubmissionExecutor.processSubmission(submission, requestHeaders);
                observer.onNext(status);
            }
            observer.onCompleted();
        });
    }

} 

class MyService{    
public void handleSubmissions(){
    final Observable<Boolean> statusObser1 = processSubmission.processSubmissionSet1(subListDtos.get(0), requestHeaders)
                .subscribeOn(Schedulers.newThread());
    final Observable<Boolean> statusObser2 = processSubmission.processSubmissionSet2(subListDtos.get(1), requestHeaders)
                    .subscribeOn(Schedulers.newThread());                   
    statusObser1.subscribe();
    statusObser2.subscribe();
    }       
}

因此，handleSubmissions在每个分配ID中使用多个线程进行调用。但是每个主线程创建并调用两个反应性java线程，并处理与每个赋值相关联的提交列表。

在保持RxJava实现性能的同时，防止redis入口争用的最佳方法是什么？有没有一个方法我可以做这个redis操作更有效的方式？

Answer 1

看起来您只是在末尾使用ops变量执行put操作，您可以隔离需要同步的点。

在我所做的简短研究中，我找不到hashoperations是否还不是线程安全的）。

但是，一个如何分离你所关心的部分的例子是这样做：

public void processSubmission(final String key, final Map<String, String> submissionDTO) {
    final String hashKey = String.valueOf(Hashing.MURMUR_HASH.hash(key));
    this.stringRedisTemplate.expire(key, 60, TimeUnit.MINUTES);
    Map<String, String> data = findByKey(key);
    String json;
    if (data != null) {
        data.putAll(submissionDTO);
        json = convertSubmission(data);
    } else {
        json = convertSubmission(submissionDTO);
    }
    putThreadSafeValue(key, hashKey, json);
}

并且有一个方法只对put操作进行同步：

private synchronized void putThreadSafeValue(key, hashKey, json) {
    final HashOperations<String, String, String> ops = this.stringRedisTemplate.opsForHash();
    ops.put(key, hashKey, json);
}

有许多方法可以做到这一点，但是看起来可以将线程争用限制在put操作。