Redis 缓存仅在异步方法中因同步请求而超时，而异步请求的响应速度较慢

首先，我将Azure Redis缓存服务和StackExchange.Redis（1.0.371）客户端与MVC 5和Web Api 2应用程序一起使用。我得到了非常有趣的行为。当我使用异步转换同步调用时，同步请求超时和响应缓慢。我举个例子。这是我的RedisCacheService，

public class RedisCacheService : ICacheService
{
    private readonly IDatabase _cache;
    private static readonly ConnectionMultiplexer ConnectionMultiplexer;
    static RedisCacheService()
    {
        var connection = ConfigurationManager.AppSettings["RedisConnection"];
        ConnectionMultiplexer = ConnectionMultiplexer.Connect(connection);
    }
    public RedisCacheService(ISettings settings)
    {            
        _cache = ConnectionMultiplexer.GetDatabase();
    }
    public bool Exists(string key)
    {
        return _cache.KeyExists(key);
    }
    public Task<bool> ExistsAsync(string key)
    {
        return _cache.KeyExistsAsync(key);
    }

    public void Save(string key, string value, int timeOutInMinutes)
    {
        var ts = TimeSpan.FromMinutes(timeOutInMinutes);
        _cache.StringSet(key, value, ts);
    }
    public Task SaveAsync(string key, string value, int timeOutInMinutes)
    {
        var ts = TimeSpan.FromMinutes(timeOutInMinutes);
        return _cache.StringSetAsync(key, value, ts);
    }
    public string Get(string key)
    {
        return _cache.StringGet(key);
    }
    public async Task<string> GetAsync(string key)
    {
        string result = null;
        var val = await _cache.StringGetAsync(key);
        if(val.HasValue) 
        {
            result = val;
        }
        return result;
    }
    ......................................................................
}

这是我调用缓存的方法。

public async Task<IList<XX>> GetXXXXX(XXXX)
{
    var key = string.Format("{0}/XX{1}_{2}", XXXX, XX, XX);
    var xxx = _cacheService.Get(key);
    if (xxx != null)
    {
        return JsonConvert.DeserializeObject<IList<XX>>(xxx);
    }
    var x = await _repository.GetXXXXX(XXXXX);
    var contents = JsonConvert.SerializeObject(x);
    _cacheService.Save(key, JsonConvert.SerializeObject(x));
    return x;
}

上面的方法总是给我，

System.TimeoutException
Timeout performing GET XXX, inst: 0, mgr: Inactive, queue: 3, qu=2, qs=1, qc=0, wr=1/1, in=0/0

或

System.TimeoutException
Timeout performing SETEX XXX, inst: 0, mgr: Inactive, queue: 2, qu=1, qs=1, qc=0, wr=1/1, in=0/0

让我们将其更改为异步，

public async Task<IList<XX>> GetXXXXX(XXXX)
{
    var key = string.Format("{0}/XX{1}_{2}", XXXX, XX, XX);
    var xxx = await _cacheService.GetAsync(key);
    if (xxx != null)
    {
        return JsonConvert.DeserializeObject<IList<XX>>(xxx);
    }
    var x = await _repository.GetXXXXX(XXXXX);
    var contents = JsonConvert.SerializeObject(x);
    await  _cacheService.SaveAsync(key, JsonConvert.SerializeObject(x));
    return x;
}

上述方法有效，但至少需要 5-10 秒。我的意思是如果没有可用的缓存，则为 10 秒，如果缓存可用，则为 5 秒。

现在让我们让我的方法完全同步，

public async Task<IList<XX>> GetXXXXX(XXXX)
{
    var key = string.Format("{0}/XX{1}_{2}", XXXX, XX, XX);
    var xxx = _cacheService.Get(key);
    if (xxx != null)
    {
        return Task.FromResult(JsonConvert.DeserializeObject<IList<XX>>(xxx));
    }
    //var x = await _repository.GetXXXXX(XXXXX);
    var x = (IList<XX>)new List<XX>();
    var contents = JsonConvert.SerializeObject(x);
    _cacheService.Save(key, JsonConvert.SerializeObject(x));
    return Task.FromResult(x);
}

请注意注释以调用存储库方法。上述方法立即起作用，意味着我在不到 1 秒的时间内得到结果。显然，Azure或StackExcahge.Redis客户端有问题。

更新：我的最后一个方法（异步）也像魅力一样工作（快速且没有错误），

public async Task<IList<XX>> GetXXXXX(XXXX)
{
    var key = string.Format("{0}/XX{1}_{2}", XXXX, XX, XX);
    var xxx = await _cacheService.GetAsync(key);
    if (xxx != null)
    {
        return JsonConvert.DeserializeObject<IList<XX>>(xxx);
    }
    //var x = await _repository.GetXXXXX(XXXXX);
    var x = (IList<XX>)new List<XX>();
    var contents = JsonConvert.SerializeObject(x);
    await _cacheService.SaveAsync(key, JsonConvert.SerializeObject(x));
    return x;
}

请注意，我仍然对存储库代码进行了注释。