Re: Problem with spid by sp_who

Matik (marzec@xxxxxxxxxxxx) writes:
> Maybe my question can be very stupid, but I'm a little confused.
> When I run sp_who on my database, I see one process (accessing remotely
> my database from another database on another SQL server) many many
> times.
>
> Well, I assume that this is one process, because I cannot imagin that
> the data aquiring can be done by almost 1000 (thousand) opened
> connections.

Unfortunately, I can imagine that. :-)

Modern applications, usually opens a connection to run a query and then
disconnects. The idea is that the API then maintains a connection pool.
That is, when the application says "close", the API lingers to the
connection for some time, typically 60 seconds, and if the application
requests a new connection with the same properties within that time,
the API will reuse the dormant connection.

But if the application is improperly written, the connection cannot be
reused. I know that there is a pitfall with SqlClient in ADO .Net. I
don't remember the exact details, but it has something to do if you
close the connection before you close the command or somesuch.

> The best part is, that when I run sp_lock, I see, that the current
> session of the client, (lets say spid 53) is locking tempdb, with
> objects id below 10 (system).

It looks as the processes have been creating objects in tempdb within
a transaction. And since the syscomments is among the listed tables,
one could suspect that it has created stored procedures. (But it could
also be default values for table columns.)

Note that if a process starts a transaction and then disconnects, but
the API retains the connection open, the transaction will remain open
until the connection is reused. (When the connection is reused, the API
issues sp_reset_connection which rollbacks transaction, reset SET options
etc.)
--
Erland Sommarskog, SQL Server MVP, esquel@xxxxxxxxxxxxx

Books Online for SQL Server 2005 at
http://www.microsoft.com/technet/prodtechnol/sql/2005/downloads/books.mspx
Books Online for SQL Server 2000 at
http://www.microsoft.com/sql/prodinfo/previousversions/books.mspx
.

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