Often a timeout

[wanghaoxing]

Timeout performing EVAL, inst: 5, queue: 1, qu: 0, qs: 1, qc: 0, wr: 0, wq: 0, in: 19, ar: 0, clientName: , serverEndpoint: 172.16.0.146:6379, keyHashSlot: 12452 (Please take a look at this article for some common client-side issues that can cause timeouts: http://stackexchange.github.io/StackExchange.Redis/Timeouts)- at StackExchange.Redis.ConnectionMultiplexer.ExecuteSyncImpl[T](Message message, ResultProcessor`1 processor, ServerEndPoint server) in c:\code\StackExchange.Redis\StackExchange.Redis\StackExchange\Redis\ConnectionMultiplexer.cs:line 2120
at StackExchange.Redis.RedisBase.ExecuteSync[T](Message message, ResultProcessor`1 processor, ServerEndPoint server) in c:\code\StackExchange.Redis\StackExchange.Redis\StackExchange\Redis\RedisBase.cs:line 81
at StackExchange.Redis.RedisDatabase.ScriptEvaluate(String script, RedisKey[] keys, RedisValue[] values, CommandFlags flags) in c:\code\StackExchange.Redis\StackExchange.Redis\StackExchange\Redis\RedisDatabase.cs:line 1052
at Microsoft.Extensions.Caching.Redis.RedisExtensions.HashMemberGet(IDatabase cache, String key, String[] members)
at Microsoft.Extensions.Caching.Redis.RedisCache.GetAndRefresh(String key, Boolean getData)
at Microsoft.Extensions.Caching.Distributed.DistributedCacheExtensions.GetString(IDistributedCache cache, String key)

[wanghaoxing]

I don't know if I'm coding it wrong
mycode

        private async Task<T> GetOrAddAsync<T>(string key, Func<T> valueFactory, DistributedCacheEntryOptions distributedCacheEntryOptions)
        {
            var valueString =  _cache.GetString(key);
            if (string.IsNullOrWhiteSpace(valueString))
            {
                lock (key)
                {
                    valueString = _cache.GetString(key);
                    if (string.IsNullOrWhiteSpace(valueString))
                    {
                        var value = valueFactory();
                        _cache.SetString(key, JsonConvert.SerializeObject(value), distributedCacheEntryOptions);
                        return value;
                    }
                }
            }
            return NewtonJsonHelper.DeserializeObject<T>(valueString);
        }

[bragma]

Hi @wanghaoxing
I am trying to fix the same problem too. I am not sure if the cause of your timeouts are the same as mine, since your exception is a bit less informative than mine (different project settings), but look at this:

https://github.com/StackExchange/StackExchange.Redis/blob/master/docs/Timeouts.md

and this:

https://gist.github.com/JonCole/e65411214030f0d823cb

In a brief, you probably have to fiddle with ThreadPool.SetMinThreads(...)

[3rzx]

Hi @bragma I deal with the same problem, too. Thanks for your answer. But I also use ThreadPool.SetMaxThreads(...) to limit the number of threads. I wonder is there any principle about setting number of MaxThreads and MinThreads ?

[analogrelay]

Thread pool starvation issues like this are a frequent problem when you use synchronous blocking APIs like GetString. You should use something like GetStringAsync instead to avoid locking up thread-pool threads. .NET has a limited number of thread-pool threads and any time you call one of these synchronous APIs (or call .Wait or .Result on a Task) you are locking-up one of these threads.

You already appear to be in an async method, so you should use the GetStringAsync method instead.

We should provide better documentation or guidance here (via deprecating functions), so I filed #1893 to do that.

[bragma]

@anurse my code is entirely async, I never use blocking version of a method if there is an equivalent async. Still, I have the problem when my azure web app restarts after a deploy/slot swap. Increasing the thread pool mitigates it.

[analogrelay]

Sounds like that's likely a different issue then. The original code sample provided did use blocking methods.