Marcus Perryman's WebLog

Hi marcpe,
I am getting multiple copies of your blog on my newsreader [Mozilla Thunderbird version 1.0.2 (20050317)].

One is coming from
https://blogs.msdn.com:443/marcpe/archive/2005/06/21/431074.aspx

and other from
http://blogs.msdn.com/marcpe/archive/2005/06/21/431074.aspx

To be exact, each post is coming 12 times, 6 times from frist source, 6 times from second source.

I have subscribed to this blog using the following link.
https://blogs.msdn.com/marcpe/rss.aspx

There is no such problem with other blogs where I have subscribed. This problem started today only.

"For a complex app, ideally the SqlCeConnection instance would be placed in a singleton wrapper class that manages access to the database."

at the cost of connection pooling =(

Marcus,

In my preliminary research on the subject, I have not found a lot of links on the web (directly from Microsoft or third-party) that talk about how one should properly handle a SqlCeConnection from multiple threads. In the blog post above, you suggest that a "multithreaded app" should provide a wrapper class around the SqlCeConnection. I'm trying to envision what this would look like.

I could imagine one approach would be to completely hide the underlying SqlCeConnection inside the wrapper and provide common database-related functionality such as OpenDatabase(), CloseDatabase(), Insert(..), Update(...), Select(...), etc. However, this seems relatively fickle. The nice thing about the SqlCeCommand interface is that it's incredibly flexible. The wrapper interface, as I defined it above, seems to dramatically reduce this flexibility. Have you thought of a clean way to wrap a SqlCeConnection such that one could still use SqlCeCommand objects?

An entirely different approach, which I have seen suggested, is to create a SqlCeConnection for each thread in the system. This would work well, I suppose, if those threads are long lived (e.g., to mitigate the cost of creating and destroying the connection). Thoughts?

I realize you made this original post ~1.5 years ago, but I thought I'd post a comment regardless. I posted a rundown of this issue at http://csharponphone.blogspot.com/search?q=SqlCeConnection.

I was unable to find much documentation on the web, but just to note that you must also call Dispose (or use the using pattern) with the SQLCeCommand object when running on Windows CE devices.  Surprisingly the same code runs perfectly without the Dispose on the Windows XP platform.

see http://support.microsoft.com/?scid=kb%3Ben-us%3B824462&x=4&y=15

We are using sql ce 3.5 and have implemented a sql connection pool that stores the connections for threads when a thread requests a connection to a database.  If the connection is no longer is in use for a period of time we dispose the command and connection to the database.  Our monitor thread is triggered by a timer that goes off incrementally that checks the state of each of the threads connections and cleans up any connections if they meet the criteria.  For some reason this implementations bleeds memory and eventually with enough connections will run out of virtual memory for a process.  As a test in our freeConnection routine I moved the connection dispose and command dispose to be done on each of the freeConnection called (same code that is executed in the timer call) and the resourced seem to get freed up correctly.  The only difference I can see is that the timer calling the monitor code is on a separate thread then the one owning the connection so I was wondering if this has an impact on the actually disposing of the connections and commands in the underlying implementation of SQL CE.

Thanks

Jake