http://blogs.msdn.com/clraddins/archive/2007/07/18/add-in-lifetime-management-pete-sheill-jim-miller.aspxA good question to ask when evaluating a design is ‘how is the lifetime of this object or component managed?’ That is, · How do you know it isn’t needed anymore? · Is it possible to release the resources while the object is still in use? · Is it possibleenCommunityServer 2.1 SP1 (Build: 61025.2)http://blogs.msdn.com/clraddins/archive/2007/07/18/add-in-lifetime-management-pete-sheill-jim-miller.aspx#3955704Thu, 19 Jul 2007 16:55:13 GMT91d46819-8472-40ad-a661-2c78acb4018c:3955704David Levine<P>One of the benefits of appdomains is it provides a separation of components into lightweight "mini-processes". However, a drawback is that sometimes it is impossible to unload the appdomain. A single thread stuck in a call to unmanaged code can prevent the appdomain from unloading - we run into this a lot as we have a great deal of legacy code we must interoperate with. </P> <P>Each appdomain that remains loaded but unusable acts as a memory and resource leak. This causes problems in long-lived services, which is one of the places we use a plugin model; we load each plugin into its own appdomain. </P> <P>Is any work contemplated or underway to better handle this scenario?</P> <P>Thanks</P>http://blogs.msdn.com/clraddins/archive/2007/07/18/add-in-lifetime-management-pete-sheill-jim-miller.aspx#4295369Wed, 08 Aug 2007 20:04:06 GMT91d46819-8472-40ad-a661-2c78acb4018c:4295369JackG<p>David, I assume you are enabling unmanaged code in your Add-in's. We can't unwind threads that are not in managed code. &nbsp;We must wait for the call to unmanaged code to return. &nbsp;The library author could use the DomainUnload event. &nbsp;Or you could possibly run the Add-in out of process. - JackG</p>