1.初步判定是c#官方驅動沒能及時釋放連接： http://stackoverflow.com/questions/7446528/mongodb-c-sharp-driver-doesnt-release-connections-then-errors

How many connections does each mongos need?
In a sharded configuration will have 1 incoming connection from the client but may need 1 outgoing connection to each shard (possibly mongos?times the number of nodes if the shard is backed by a replicaset).
This means that the possible number of open connections that a server requires could be ?(1 + (N*M) * C)where N = number of mongos?shards, M = number of replicaset nodes, and C = number of client connections.

Why does ? mongos? never seem to give up connections??
mongos uses a set of connection pools to communicate to each shard (or shard replicaset node). These pools of connections do not currently
constrict when the number of clients decreases. This will lead to a possibly large number of connections being kept if you have even used the mongos
instance before, even if it is currently not being used.?

How can I see the connections used by mongos? ??
Run this command on each instance: mongos
db._adminCommand("connPoolStats" );?

https://jira.mongodb.org/browse/CSHARP-331

2.設置了sockettimeout=300000沒能生效： http://www.mongodb.org/display/DOCS/Connections ，單位應該是ms，不行的話換sockettimeoutms試試~~

應該就是這個原因了，是sockettimeout的單位是tick，不是毫秒。

?

?

?

3.剛開始全部啟動測試時，很有可能崩掉一大片

?

4. ? ?社區給我的答案，沒試過

? http://www.mongodb.org/display/DOCS/Troubleshooting#Troubleshooting-Socketerrorsinshardedclustersandreplicasets

?

5.2012-04-11補充，對mongo重新做了些測試，發現有兩種情況會導致，一個連接超時，默認是30s，另外一個是連接的關閉，不要輕易調用connect.close

關于Mongodb的“無法從傳輸連接中讀取數據”