CODEWITHSUNDEEP
sqlsql-server-2008sessionconnection-stringsql-server-mars
Mariano G
Mariano G

Reputation: 255

Net_Transport TPC and Session with MARS Enabled

I'm working on a site with several apps and services with EF and the database is throwing the following error:

 The server will drop the connection, because the client driver has sent multiple 
 requests while the session is in single-user mode. This error occurs when a client 
 sends a request to reset the connection while there are batches still running in 
 the session, or when the client sends a request while the session is resetting 
 a connection. Please contact the client driver vendor.

So I searched on my connections strings for each app and service to ensure that MultipleActiveResultSets was enabled, and in all connections is enabled.

So run the following query

SELECT 
    c.session_id, c.net_transport,
    s.host_name, 
    s.login_name
    , c.connect_time
FROM sys.dm_exec_connections AS c
JOIN sys.dm_exec_sessions AS s
    ON c.session_id = s.session_id
ORDER BY login_name

And see that I've for the same Login_name (same app) has multiple connections, but some connections have TCP net_transport and others "session", for the same login_name (same connection string)

What could cause that some connections use TCP instead of Session?

EDIT: This query returns for example:

session_id   net_transport   host_name    login_name   connect_time                  
196           TCP             P3417722     UserName    2015-01-05 08:57:58.437   
196           SESSION         P3417722     UserName    2015-01-05 08:57:58.437   
.
.
.

Notice that both have the same session_id and the same connect_time.

This means that I've two connections with the same username but one is with "Mars" enabled and the other doesn't?

Upvotes: 2

Views: 1142

Answers (1)

Theo Ekelmans
Theo Ekelmans

Reputation: 1

Yep, i see that all the time on my servers.

Some frameworks (EF6, LINQ) can have TCP and SESSION connections at the same time, due to usage of connection pooling techniques.

My pet pieve is that Session should be TCP+MARS ;)

Upvotes: 0

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