Is Disposing of Entity Framework context object required

Question

We are using entity framework for communication with database in our WCF service methods, recently we run the code review tool on our service code. As usual we got many review proposals by tool and many review comments were suggesting to dispose the Entity Framework context object. So, my question is if I use a Entity Framework context object within a method and once I come out of the method, GC doesn't clean up the context object ? do we need to explicitly dispose context object ?

Answer 1

Simply: DbContext implements IDisposable, therefore you should dispose of it, manually, as soon as you're done with it.

You don't need to dispose of it, because the GC will collect it eventually, but the GC isn't deterministic: you never know when "eventually" will be. Until it's disposed, it will be holding resources that aren't in use - for example, it may still have an open database connection. Those resources aren't freed until the GC runs, unless you dispose manually. Depending on specific details you may find that you have unnecessarily blocked network resources, file accesses, and you will certainly be keeping more memory reserved than you need to.

There's a further potential hit, too: when you dispose of an object manually, the GC doesn't typically need to call the Finalizer on that object (if there is one). If you leave the GC to automatically dispose of an object with a Finalizer, it'll place the object in a Finalizer Queue - and will automatically promote the object to the next GC generation. This means that an object with a finalizer will always hang around for orders of magnitude longer than it needs to before being GCed (as successive GC generations are collected less frequently). DBContext would likely fall into this category as the underlying database connection will be unmanaged code.

(Useful reference.)