Memory Leak in C#

c# .net memory-leaks garbage-collection managed
Joan Venge picture Joan Venge · Mar 6, 2009 · Viewed 49.2k times · Source

Is it ever possible in a managed system to leak memory when you make sure that all handles, things that implement IDispose are disposed?

Would there be cases where some variables are left out?

Answer

Reed Copsey picture Reed Copsey · Mar 7, 2009

Event Handlers are a very common source of non-obvious memory leaks. If you subscribe to an event on object1 from object2, then do object2.Dispose() and pretend it doesn't exist (and drop out all references from your code), there is an implicit reference in object1's event that will prevent object2 from being garbage collected.

MyType object2 = new MyType();

// ...
object1.SomeEvent += object2.myEventHandler;
// ...

// Should call this
// object1.SomeEvent -= object2.myEventHandler;

object2.Dispose();

This is a common case of a leak - forgetting to easily unsubscribe from events. Of course, if object1 gets collected, object2 will get collected as well, but not until then.

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