Ans:
When you create any object in C#, CLR (common language runtime) allocates memory for the object from heap. This process is repeated for each newly created object, but there is a limitation to everything, Memory is not un-limited and we need to clean some used space in order to make room for new objects, Here, the concept of garbage collection is introduced, Garbage collector manages allocation and reclaiming of memory. GC (Garbage collector) makes a trip to the heap and collects all objects that are no longer used by the application and then makes them free from memory.
Basically, heap is managed by different 'Generations', it stores and handles long-lived and short-lived objects, see the below generations of Heap:
0 Generation (Zero): This generation holds short-lived objects, e.g., Temporary objects. GC initiates garbage collection process frequently in this generation.
1 Generation (One): This generation is the buffer between short-lived and long-lived objects.
2 Generation (Two): This generation holds long-lived objects like a static and global variable, that needs to be persisted for a certain amount of time. Objects which are not collected in generation Zero, are then moved to generation 1, such objects are known as survivors, similarly objects which are not collected in generation One, are then moved to generation 2 and from there onwards objects remain in the same generation.
Managed objects are created, managed and under scope of CLR, pure .NET code managed by runtime, Anything that lies within .NET scope and under .NET framework classes such as string, int, bool variables are referred to as managed code.
UnManaged objects are created outside the control of .NET libraries and are not managed by CLR, example of such unmanaged code is COM objects, file streams, connection objects, Interop objects. (Basically, third party libraries that are referred in .NET code.)
Unmanaged Resource
When you create any object in C#, CLR (common language runtime) allocates memory for the object from heap. This process is repeated for each newly created object, but there is a limitation to everything, Memory is not un-limited and we need to clean some used space in order to make room for new objects, Here, the concept of garbage collection is introduced, Garbage collector manages allocation and reclaiming of memory. GC (Garbage collector) makes a trip to the heap and collects all objects that are no longer used by the application and then makes them free from memory.
Basically, heap is managed by different 'Generations', it stores and handles long-lived and short-lived objects, see the below generations of Heap:
0 Generation (Zero): This generation holds short-lived objects, e.g., Temporary objects. GC initiates garbage collection process frequently in this generation.
1 Generation (One): This generation is the buffer between short-lived and long-lived objects.
2 Generation (Two): This generation holds long-lived objects like a static and global variable, that needs to be persisted for a certain amount of time. Objects which are not collected in generation Zero, are then moved to generation 1, such objects are known as survivors, similarly objects which are not collected in generation One, are then moved to generation 2 and from there onwards objects remain in the same generation.
Managed objects are created, managed and under scope of CLR, pure .NET code managed by runtime, Anything that lies within .NET scope and under .NET framework classes such as string, int, bool variables are referred to as managed code.
UnManaged objects are created outside the control of .NET libraries and are not managed by CLR, example of such unmanaged code is COM objects, file streams, connection objects, Interop objects. (Basically, third party libraries that are referred in .NET code.)
Unmanaged Resource
When we create unmanaged objects, GC is unable to clear them and we need to release such objects explicitly when we finished using them. Mostly unmanaged objects are wrapped/hide around operating system resources like file streams, database connections, network related instances, handles to different classes, registries, pointers etc. GC is responsible to track the life time of all managed and unmanaged objects but still GC is not aware of releasing unmanaged resources
There are different ways to cleanup unmanaged resources:
- Implement
IDisposableinterface andDisposemethod - '
using' block is also used to clean unmanaged resources
There are couple of ways to implement
Dispose method:- Implement
Disposeusing 'SafeHandle' Class (It is inbuiltabstractclass which has 'CriticalFinalizerObject' and 'IDisposable' interface has been implemented) Object.Finalizemethod to be override (This method is clean unmanaged resources used by particular object before it is destroyed)
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