This question already has answers here:
Can .NET Task instances go out of scope during run?
(2 answers)
Closed 8 years ago.
Lets assume I run such a code
Task.Factory.StartNew(...).ContinueWith(...);
I don't store reference for neither of two created tasks so can I be sure that they won't be disposed before starting or at the process of executing? If yes then where do reference to these tasks are being held?
A reference to a TPL Task is held by the system under two conditions:
The Task is scheduled
The Task is running
Upon completion of the Task and any child tasks, the reference is thrown away. References in your code will behave as expected.
I believe you have some confusion regarding garbage collection and Dispose. This question may enlighten you.
Difference between destructor, dispose and finalize method
Destructor implicitly calls the Finalize method, they are technically same. Dispose is available with those object which
implements IDisposable interface...
Should you dispose Tasks?
Stephen Toub says:
No. Don’t bother disposing of your tasks.
https://devblogs.microsoft.com/pfxteam/do-i-need-to-dispose-of-tasks/
Related
This question already has answers here:
When would you ever use nested locking?
(3 answers)
Closed 11 months ago.
It says here :
While a lock is held, the thread that holds the lock can again acquire and release the lock.
Question. For what purpose can several consecutive locks be used in one thread? Or does it give nothing, but the article says to clarify that inside one thread the code in the second lock will also be executed because the lock is used in the same thread?
I just want to understand the purpose of this information.
Its called recursive locking. It is useful if you have complex paths that may end up trying to lock a resource twice (like in a recursive function). It saves you have to keep track of whether or not you already have a lock.
It is typically implemented as a counter, after the first lock subsequent locks just increment the counter, unlocks decrement, when the count reaches 0 the mutex is released
This question already has answers here:
what is relation between GC, Finalize() and Dispose?
(3 answers)
Does C# app exit automatically dispose managed resources?
(4 answers)
What are the uses of "using" in C#?
(29 answers)
Closed 2 years ago.
I got stuck in the weeds of how IDisposable and the GarbageCollector work.
Suppose you have an IDisposable object, which doesn't actually have an resources that it's holding onto (but the Dispose() method is going to do something when called). And suppose you declare it in the head of a using block, but don't actually interact with the object over the course of the block.
What guarantees do I have about how GarbageCollection will operate?
i.e.
using(new MyConceptuallyDisposableObject())
{
DoSomeWork();
await DoSomeAsyncWork();
}//PointX
Note that:
MyConceptuallyDisposableObject doesn't declare a finaliser / destructor.
(Assume that developers will never forget to using`.Dispose()` my object)
MyConceptuallyDisposableObject doesn't call GC.SuppressFinalise(this) anywhere.
Am I guaranteed that the object that I constructed will:
Will not have .Dispose() called on it before PointX?
Will have .Dispose() called on it at exactly PointX?
Will not get GarbageCollected/Finalised at any point before PointX?
Will not get GarbageCollected/Finalised before it has had .Dispose() called on it?
Suppose I then change my code to make MyConceptuallyDisposableObject call GC.SuppressFinalise(this) in its constructor. (Bearing in mind that there isn't any Destructor or Finaliser)
Does that change any of the answers to the specific questions above?
Does anything change in general, then?
Does it mean that the GC never cleans up my object at all and I'll end up with a memory leak?
*Context:*
Posted for those who are inevitably curious, but PLEASE don't answer based suggesting other ways to achieve this or that I shouldn't do this. Right now, I'm much more invested in understanding the guts of the above concepts in their abstract sense, not discussing whether my initial attempt was sensible.
I want to write a DisposableAction() class, which accepts 2 Actions. One to perform when you construct it, and one to perform when you Dispose() it.
I thought I knew all the answers to the above (and that they were "Yes", "Yes", "Yes", "Yes", "No", "Almost nothing unless you're incredibly perf-sensitive", and "No".), but I've been trying to diagnose a bug which appears to contradict these beliefs.
IDisposable and garbage collection are unrelated, except for the one situation where an object implements a finalizer that happens to call .Dispose().
Unless you know for sure, 100%, and explicitly, that an object has a finalizer that calls .Dispose() then you must call .Dispose() explicitly (or with a using) to ensure the object is disposed.
The answers to your questions:
Yes.
Yes.
Yes.
Yes.
No.
No.
No.
This question already has an answer here:
What message I receive when I kill my program with task manager
(1 answer)
Closed 9 years ago.
As the object says:
How to call the Class destructor when the process is killed with TaskManager?
the class destructor is called upon by the GC, as said in MSDN, meaning it is called by the program. when we close application from the task manager, we forcibly close the program, meaning we don't let the GC go through the object, and even if it did, the GC wouldn't know to release the object, and even if it did, there is no meaning to that because we release all the memory just after
This question already has answers here:
Closed 11 years ago.
Possible Duplicate:
Finalize vs Dispose
Dispose - This will free up the object memory and GC should be supperessed in this case.
Finalize - In case the object is not disposed and when then object goes out of the scope(I mean when the class goes out of the scope) GC will say Finalize to clean it up.
Destructor - Don't know. Can you explain difference b/w destructors and finalize ?
Dispose cannot free up memory. The Dispose() method releases or closes the unmanaged resources.
Finalize
It is used by the Garbage Collector implicitly to free the space.
Destructor
It is used to destroy the variable's value.
The destructor implicitly calls finalize, so it is sort of a pre-finalize.
See MSDN for more details. One important tidbit from that documentation:
Even with this explicit control over resources, the destructor becomes a safeguard to clean up resources if the call to the Dispose method failed.
Descrtuctor is in c++ and Finalizers are in .NET. Althought the way your represent a finalizer in C# code looks like a C++ descructor, but it's not the same and its behavior is different too.
Finalization is the last process that happens in .NET memory management. Disposing is the pattern one cleans up unmanaged memory. Remember that Dispose is the operation carried out manually or explicitly called basis, whereas finalizer is not. It's automatic by the run time.
You may wish to read this
This question already has answers here:
Closed 11 years ago.
Possible Duplicate:
Proper use of the IDisposable interface
When is Dispose necessary?
If I write a class, which uses graphics, or threads for example, must I implement the IDisposable interface to write a Dispose() method or else memory leak occurs?
Does Dipose() run when the GC reaches it?
If I implement a Dispose() method, shall I call Dispose() on all the disposable fields in the class when "disposing" parameter is true, or is it automatic?
What is "unmanaged resource"?
So I'm pretty unsure about it, I'd appreciate anything that helps me understand these things :)
Thank You
IDisposable is just a pattern to follow. It doesn't do anything, in and of itself, special (other than fitting the requirements of the using statement).
If you're working with a native resource, the resource isn't "known" to the garbage collector. IDisposable is the convention used to allow you to free this resource deterministically.
For details, I wrote a detailed series on IDisposable which talks about why and how to implement it for various scenarios (including wrapping a native resource, encapsulating other IDispsable types, etc).