First of all I am using Azure Redis Cache service and StackExchange.Redis(1.0.371) client with my MVC 5 and Web Api 2 app. I am getting very interesting behaviors. getting timeout with sync requests and slow response when I convert my sync calling with async. Let me give you an example. Here is my 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;
}
......................................................................
}
and here is my method which invokes the cache.
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;
}
The above method always gives me,
System.TimeoutException
Timeout performing GET XXX, inst: 0, mgr: Inactive, queue: 3, qu=2, qs=1, qc=0, wr=1/1, in=0/0
or
System.TimeoutException
Timeout performing SETEX XXX, inst: 0, mgr: Inactive, queue: 2, qu=1, qs=1, qc=0, wr=1/1, in=0/0
Let change it to async,
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;
}
This above method works but it takes at least 5-10 seconds. I mean 10 seconds if no cache is available and 5 seconds if cache is available.
Now lets make my method completely sync,
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);
}
Please note the comment to call a repository method. The above method work instantly, means I get result within less than 1 seconds. Clearly something wrong with Azure or StackExcahge.Redis client.
Update: My last approach(async) is also working like a charm(fast and no error),
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;
}
Note that still I have commented the repository code.