c# find unused objects of specific class before garbage collection

Hello and thank you very much for your help!

Does anybody have a good idea to find unreferenced objects of a specific class before garbage collection? (preferable as soon as possible)

In my case, I need to create a lot of small objects of a specific class for temporary use only. The problem is that I don’t know when the object is开发者_运维技巧 not needed anymore. I would like to collect the objects of that class which are not referenced any more (as soon as possible) before garbage collection so that I can recycle them and don’t need to create them new. I think that would make the code much faster.

Kind Regards, David

First off, before you do this you should do extensive profiling to determine that you really, truly do have a performance problem caused by collection pressure. The garbage collector is highly tuned and works quite well most of the time; situations where you need to pool objects for performance reasons are rare.

I actually am in that scenario; we have determined through extensive testing that there are certain objects we use all the time on a temporary basis, ("builders" of other objects, essentially) and that the cost of collection pressure caused by re-allocating them frequently is measurable and high.

What we do is we have a pool class which maintains an array of "blank" objects. When you need a new object, the pool checks the array and returns an object that is in the array if we have one, nulling out the array entry. If we don't have one then it creates a new object. When the temporary user is done with the object, it passes it back to the pool, which "blanks" it and sticks it back in the array. (Growing the array if necessary.)

If a user forgets to put the object back into the pool, or cannot do so because an exception was thrown before the "back in the pool" call, who cares? All we've done in that case is perhaps slightly de-optimized a future allocation. The cost is that you need to remember to put the object back in the pool when you're done with it.

There's no way to "hook" the garbage collector to put stuff back in the pool automatically that I know of.

You can't directly control garbage collection, but you could create a manager class that is responsible for creating, holding the references and disposing of these objects. As long as the manager class is in scope, its objects will not be garbage collected.