问题:并发稍微多的情况下Redis偶尔返回超时
StackExchange的Redis类库,用的较多,但偶尔报的问题非常让人迷惑,访问超时,队列XXX…
问题出在Redis服务器吗?可是其他应用访问都正常啊,难道要把这个类库替换掉?
问题描述如下:
Timeout performing GET keyName, inst: 1, mgr: ExecuteSelect, err: never, queue: 20, qu: 20, qs: 0, qc: 0, wr: 0, wq: 0, in: 0, ar: 0,
clientName: computerName, IOCP: (Busy=0,Free=1000,Min=4,Max=1000), WORKER: (Busy=4,Free=32763,Min=4,Max=32767),
Local-CPU: unavailable (Please take a look at this article for some common client-side issues that can cause timeouts:
https://github.com/StackExchange/StackExchange.Redis/tree/master/Docs/Timeouts.md)
给出了参考网址?
StackExchange给出了这个问题的解释和一般方案?那难道真的是我的工作线程比较多吗?我抱着试试看的态度,自己写了个测试用例:
code = StatusCode.OK;
// ThreadPool.SetMinThreads(200, 200);var ts = new List<Task>();for (int i = 0; i < 100; i++){var a = i;var t = new Task(() =>{var l = this.Context.TryGetLock("123");Trace.WriteLine($"{a}:{l!= null}");int workerThreads, completionPortThreads;ThreadPool.GetAvailableThreads(out workerThreads, out completionPortThreads);Trace.WriteLine($"Available: WorkerThreads: {workerThreads}, CompletionPortThreads: {completionPortThreads}");});t.Start();ts.Add(t);}Task.WaitAll(ts.ToArray());return null;
问题复现了,就是提示类似错误,把注释ThreadPool.SetMinThreads(200, 200);开启,问题消除。
结论
问题的解决在于启用task后,task入队后导致redis客户端超时,客户端。。。
因此解决的重点在于设置线程池的最小大小:
ThreadPool.SetMinThreads(200, 200);
小备注
之前改过连接超时,稍微改大点,也可以缓解该问题,但仅此而已。
StringBuilder sb = new StringBuilder();sb.AppendFormat("{0}:{1}", cfg.Server, cfg.Port);sb.AppendFormat(",allowAdmin={0}", cfg.AllowAdmin);sb.AppendFormat(",abortConnect=false,connectRetry=3,syncTimeout=2500");sb.AppendFormat(",connectTimeout={0}", cfg.ConnectTimeout>0?cfg.ConnectTimeout:5000);if (cfg.Ssl){// sb.AppendFormat(",ssl={0},password={1}", cfg.Ssl,cfg.Pwd);sb.AppendFormat(",password={1}", cfg.Ssl, cfg.Pwd);}
syncTimeout :超时会影响redis取值的超时,但是开多个task时,超时设置非常大也解决不了。