聊聊程式

問題是 第一次執行專案 或 在IIS 上跑 都一樣 常常第一次連線就會timeout
但是偶而就正常 大約 10次 9死 1通
只要第一次timeout後 之後就都會沒問題
錯誤訊息
A timeout occured after 30000ms selecting a server using CompositeServerSelector
{ Selectors = MongoDB.Driver.MongoClient+AreSessionsSupportedServerSelector, 
LatencyLimitingServerSelector{ AllowedLatencyRange = 00:00:00.0150000 } }. 
Client view of cluster state is { ClusterId : "1", ConnectionMode : "Automatic", Type : "Unknown", 
State : "Disconnected", Servers : [{ ServerId: "{ ClusterId : 1, EndPoint : "127.0.0.1:27017" }", 
EndPoint: "127.0.0.1:27017", ReasonChanged: "ServerInitialDescription", 
State: "Disconnected", ServerVersion: , TopologyVersion: , Type: "Unknown", 
LastHeartbeatTimestamp: null, LastUpdateTimestamp: "2020-09-01T02:10:14.8130149Z" }] }.

經過一連串的比對 測試
後來才發現是 MongoDB.Driver 套件版本問題
新開專案 所以都是下載最新版本 2.11.0
舊專案都是2.2.4 
我改安裝2.2.4就正常了
MongoDB版本是3.4.10

參考
MongoDB Compatibility

It is recommended to store a MongoClient instance in a global place, either as a static variable or in an IoC container with a singleton lifetime.