Re: Question about IDispose
From: Alvin Bruney [MVP] (vapor)
Date: 02/25/04
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Date: Wed, 25 Feb 2004 10:53:38 -0600
> For SqlConnection, IDisposable.Dispose() simply calls
> SqlConnection.Close() if the connection is not already closed. So it
> handles pooling just fine (at least as well as Close() does).
well that's really what i was looking for. if that's true, the problem is
resolved then. and i assume mysqlconnection would follow that same pattern.
i was thrown off by this response which seemed to indicate to me at least
that this wasn't happening
>Using should blindly call Dispose. It would be up to the object implementer
>to write a Dispose method that works properly with the pooling system
phew. ok all is well now. you guys can go back to work.
thanks
-- Regards, Alvin Bruney [ASP.NET MVP] Got tidbits? Get it here... http://tinyurl.com/3he3b "mikeb" <mailbox.google@mailnull.com> wrote in message news:ugIYGz0%23DHA.2512@TK2MSFTNGP11.phx.gbl... > Alvin Bruney [MVP] wrote: > > > Probably I was misunderstood. I'll restate for clarity. > > > > > > > > Implementing the using construct disposes of the object in question. The > > connection pool is specifically setup to prevent object destruction because > > it is inherently expensive to create this object. It is much more efficient > > to reuse the object instead of destroying it. > > > > This behavior poses no problem in a windows environment because connections > > are cheap, however, the reverse is true in a web environment. > > > > > > > > Should the dispose pattern be smart enough to detect pooling? After thinking > > about it, Jon is right. Because of how the finalizer works, it is faulty to > > place dependency in the overridden dispose function. So it cannot check for > > a connection pool flag before destroying the object, at least based on > > microsoft's best practices. So the *fix cannot come from the Dispose layer. > > > > > > > > Should the fix be implemented at a higher level such as the connection > > object layer? After thinking about it, I don't think so for the same reason; > > it forces the connection object into knowing more than it is supposed to > > about the environment in which it is run. But this doesn't solve the > > problem. The problem still remains that the benefits of the pool are being > > negated. Why is this important? Consider a high volume website fielding > > 20000 hits per day. The benefits of pooling here make or break the website. > > Negating these benefits is simply not acceptable and must be avoided. But > > how can I avoid it if I don't know the negative effects? > > > > > > > > What I am suggesting is that Microsoft append a qualifying comment to the > > dispose pattern literature indicating that the using construct which > > implements the IDispose pattern not be used in combination with object > > pooling for web applications because the benefits of pooling may be > > negatively affected. With that recommendation in the literature, I can > > safely avoid the using construct at a high level and choose to manually > > close my objects guaranteeing that the connection pool benefits remain in > > effect since calling close() only flags the object for reuse anyway. > > > > > > > > > >>Are you *sure* that using the above pattern is actually ignoring > > > > connection pooling? > > > > > > > > No, I am not 100%sure. But based on the literature, I make an educated guess > > that it ignores pooling because the dispose implementation must make no > > assumptions about the environment. > > The Dispose() implementation is provided by the class - so it knows the > environment intimately. > > For SqlConnection, IDisposable.Dispose() simply calls > SqlConnection.Close() if the connection is not already closed. So it > handles pooling just fine (at least as well as Close() does). > > > -- > mikeb
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