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I mean, probably, but I don't usually code for VB developers
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
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you sound like you didn't give how to use unmanaged resource any sort of serious thought!
to be fair.. in the last 10 years I never had to use unmanaged resource (explicitly) in .NET!
But you have to keep in mind.
1. .NET use a lot of unmanaged resource. But it's done in a lot of nicely encapsulated OS/Utility class. For example WPF use tons of them to render DirectX content. It's also very common in WinForm, all those Bitmap, Cursor, Brush, etc... all wrap unmanaged OS resources.
2. once upon a time, before .NET 3.5, one often had to use unmanaged resource explicitly to use OS class not nicely wrapped. Hence how to properly use them was much more common knowledge back then.
Additionally what has unmanaged resources to do with VB?
If anything, my natural prejudice against VB developers would have me say that VB developer can't properly handle unmanaged resources!
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Actually have given it a lot of thought, and in the end I decided not to use Finalizers.
Here's why, and I think it's justifiable: Win32 process segregation. You will clean all handles on proc exit RIGHT AFTER the GC cleans up it's Finalized objects. Win32 handles what .NET won't, usually at the same time.
There's one exception - remote COM objects. I will clear handles on those, but doing RPC is its own topic, and lifetime considerations are a huge one.
As far as your final sentence, that was rather my point. My audience isn't VB developers. If I was targeting them I'd make my code drool proof. =)
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
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At any rate I don't understand your beef against finalizers..
- it avoids memory / resource leaks regardless of whoever use your API. i.e. it makes garbage collection collect your resources, isn't that nice?
- it has no performance impact if you call Dispose explicitly
- it's 3 line of code to implement properly...
therefore I am just completely nonplussed by your... reluctance about them...
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I just don't have a good enough justification to use because it doesn't prevent resource leaks - win32 does that, as I said.
I've never seen .NET even call finalizers 99% of the time until just before process exit.
Which means your VB developer who is not using anything like using(var brush = ) is still creating a ton of handles that will remain uncollected for the lifetime of the app. And GC has no way of knowing when GDI is out of handles. So it just lets them get eaten, even with your finalizers.
Until your proc exits. At which point win32 cleans up anyway. Now tell me I'm wrong about any of this?
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
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codewitch honey crisis wrote: I just don't have a good enough justification to use because it doesn't prevent resource leaks - win32 does that, as I said.
This class is potentially leaking, and Win32 is NOT magically fixing it.
public class Class : IDisposable
{
IntPtr unmanaged;
public Class()
{
unmanaged = Marshal.AllocHGlobal(10);
}
public void Dispose()
{
Marshal.FreeHGlobal(unmanaged);
unmanaged = IntPtr.Zero;
}
}
And this class is not leaking and is nicely garbage collected.
public class Class : IDisposable
{
IntPtr unmanaged;
public Class()
{
unmanaged = Marshal.AllocHGlobal(10);
}
~Class() { Dispose(false); }
public void Dispose()
{
Dispose(true);
GC.SuppressFinalize(this);
}
protected void Dispose(bool disposing)
{
Marshal.FreeHGlobal(unmanaged);
unmanaged = IntPtr.Zero;
}
but the real question is... why do you refuse to do implementation 2? What so complicated or costly about it? Why do you so adamantly want to introduce memory leak? That doesn't make no sense!
BTW bonus implementation with explicit memory pressure
public class Class : IDisposable
{
IntPtr unmanaged;
public Class()
{
unmanaged = Marshal.AllocHGlobal(10);
GC.AddMemoryPressure(10);
}
~Class() { Dispose(false); }
public void Dispose()
{
Dispose(true);
GC.SuppressFinalize(this);
}
protected void Dispose(bool disposing)
{
if (unmanaged != IntPtr.Zero)
{
Marshal.FreeHGlobal(unmanaged);
GC.RemoveMemoryPressure(10);
unmanaged = IntPtr.Zero;
}
}
}
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Again, Win32 cleans up that HGLOBAL leak on process exit.
So does Finalize.
Maybe if I'm slamming the garbage collector i can get finalize to be called before proc exit. in the real world i've pretty much never seen that happen.
so until they do, I see no reason to use it.
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
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Let be me more explicit here.
A) You cannot leak HGLOBAL outside of a process. Any process allocated resource will be freed on process exit, managed or not.
B) Finalized objects are placed in a special list, and generally their finalizers get called right before proc exit.
Since A, B is redundant. Meaning the code is redundant.
I don't leak. And I don't use finalize.
But I do dispose.
The exception is maybe RPC, but worst I'd maybe do this
#if DEBUG
void Finalize() {if(!_isDisposed) {System.Diagnostics.Debug.WriteLine("Error: Object not disposed"); System.Diagnostics.Debugger.Break();} }
#endif DEBUG
so you could catch it in a debug session.
I don't believe in using that set aside list - it adds unnecessary churn to the GC.
I'd rather report the failure, because if you're not disposing you're also running into other problems finalize won't help you with - like stepping on unclosed files or worse, running out of GDI handles. Before finalize ever gets a chance to be called.
At any rate, I don't use unmanaged resources directly on serious projects, so you won't find it an issue in my code.
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
modified 14-May-19 23:29pm.
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yes, on process exit memory is collected.
but general purpose class in a reusable library should not limit to such narrow scenario (of short living utility process). Particularly when there is an easy 3 line fix.
For example what if you wrapped an HBITMAP in a nice C# resource in a drawing program that can be left open for hours or days.. but every now and then the computer will slow down dramatically and the user will reboot because he has no idea what's going on...
or maybe he will investigate the problem and realize it's that "sh*t drawing program" that is leaking memory again! That's not something I want to happens to my users...
Or for another example you got this webserver running 24/7 serving millions request every hours....
But then, suddenly, the process becomes super slow and the webserver need be restarted every hour it turns out. unacceptable!
Finally do you really want to tell a potential job interviewer you don't bother making your resource garbage collection friendly because one can just restart the application?!
modified 14-May-19 23:35pm.
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Show me where Finalized objects get collected before proc exit in a real world scenario.
Except server apps, but if you're using unmanaged resources directly from a webserver i hate you.
In application code, the GC calls finalizer before proc exit. Show me where it doesn't.
Contrive a scenario even.
It won't slow down dramatically until reboot. The kernel keeps an slist of kernel handles by process around. Win32 does indeed clean them when the process exits. Your HBITMAP will be around until proc exit, not until reboot.
And *it would anyway* - at least in my tests, because Finalize doesn't get called until proc exit anyway.
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
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this is going nowhere so I will stop trying to convince to write proper utility classes.
although I will just add 2 (last) things:
- for the record memory management, and even dispose, is indeed totally useless if all you have is short running processes. the issue is all about singular long running process running as long as possible. which you seem to dismiss so casually for some mysterious reason
- you were asking for a sample that show if finalizer are even ever called. well run the winform app below as a console app (to see the Console.WriteLine() output), press the button a few times, tab out and in, do it again. you will see that finalizer are indeed called sometimes.
class Program
{
static void Main(string[] args)
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new MyForm());
}
}
public class MyForm : Form
{
public MyForm()
{
var b = new Button
{
Text = "Click",
Dock = System.Windows.Forms.DockStyle.Fill,
};
b.Click += (o, e) => { new Foo(); };
this.Controls.Add(b);
}
}
public class Foo
{
const int N = 100_000;
<pre>
IntPtr unmanaged;
public Foo()
{
unmanaged = Marshal.AllocHGlobal(N);
GC.AddMemoryPressure(N);
}
~Foo()
{
Console.WriteLine("in finalizer");
}
}</pre>
modified 15-May-19 0:23am.
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I'll try running that. But yeah for now, let's agree to disagree. I'll kick around what you wrote. You may have changed my mind if that sample pans out.
The last time i actually tested this was pre .NET 3
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
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I should add, the only time I'll write a "Utility" class it's static. I use the convention a lot, but never for anything instantiated. That's just me. =) so when you said Utility class my first thought, was , where would I keep the state?
At any rate, it impacts nothing I've written since .NET 2 days, but if I do write some unmanaged wrapper I'll keep this exchange in mind.
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
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I don't think it matters when I analyse your opinion but...
I want to point out that while finalizers are unpredictable, that doesn't mean they are unreliable.
Finalizers are very reliable. But they only happens once in a while.
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What I mean is you can't rely on them to close something before you run into trouble.
Again, this may have changed in newer .NET renditions - since i tested which was a decade ago at least. It looks like your sample does indeed finalize on collect.
Still, I question whether it would collect often enough to keep up with the leakage from not calling dispose. It never did in the past for me.
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
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I have trouble understanding your statements... So here are some facts...
Using memory pressure hint you can be sure it will suggest to the runtime enough GC that you don't run out of memory or become slow or fragmented. This is, however, something that is only marginally useful, I didn't notice any obvious improvement after using that hit. I guess I never allocated huge unmanaged memory pages.
If your code is using other precious system resource, like a Window handle, or a brush handle or a socket... you might be out of luck. You might run out those without the system realizing a system GC is needed.
I can't even start to guess what you mean when you wrote "finalizer keep up with the leakage from not calling dispose"
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Super Lloyd wrote: If your code is using other precious system resource, like a Window handle, or a brush handle or a socket... you might be out of luck. You might run out those without the system realizing a system GC is needed.
As it happens, this is just what I meant. If you use things like this, the GC won't necessarily keep up with your creation of objects. You can run out of GDI handles (though maybe not window handles - for other reasons) pretty quickly and Finalize won't help you, or at least that has happened to me.
One of the reasons I won't use GDI handles and such in serving web pages - at least not directly, is the unpredictability of them. What if the connection gets broken and ASP.NET or whatever halts your thread? Sure your finalizers will still run, but when? Will you have enough handles left to serve the next request?
(At least if you call dispose faithfully your odds are better but still)
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
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OIC.. you went from finalizer are not good enough to I flat out to waste time implementing them...
Sure enough finalizer won't help with those sparse handle on a web server. And hey, it's really ease to dispose of things in webservice application usually.
On the other hand you will run out of handle much more slowly in a user desktop application. And also some object can be very hard to track in desktop application, making finalizer really useful. And finalizer will run in a timely fashion there.
And utility class are not always static. For example string, Cursor, Bitmap, Regex, etc... (many of the 21,000+ class in the .NET framework BCL) are instantiable utility classes!
And I also happen to love writing my own.
In fact I shared DiceSet class with you, as a free custom example!
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I just meant i think we define utility differently. mine is narrow when it comes to C# and .NET has but a few. - and it's just a convention i use in my own personal style. i've just been using it so long that it impacts how i understand the word, if that makes sense. I'm not saying you're wrong.
I responded a bit to your dice thread. i think we can get you from theory to code if you just explain the "meaning" of the dice syntax. I don't do tabletop gaming. i have friends that are into that stuff but i never was.
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
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Nice!
I was planning to look at it tonight.. I don't have the code here, it's personal stuff!
The meaning is, you can often read: roll things like "3d6+2" and I try to create an object than can roll that, i.e. a dice collection with 3 x D6 (a Dice class that roll between 1 to 6) and sum them all up and adds 2.
Or maybe "D10+D4+1" which would be Dice (10) (roll between 1 to 10) + roll Dice (4) (between 1 to 4) plus 1.
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That's an expression evaluator!
just look at the sample in my stuff. Oh there's a bug in the parser runtimes it both is and isn't serious but it's an 8 character long fix and it still works atm =). I can reupload and wait for reapproval but i'll do that tomorrow.
The question is, can you just roll while you parse? or do you NEED an object model?
because if you need an object model parsing is a two step process. (like, do you need Dice and DiceSets or can you just pass an expression to an Eval function and get your answer out? because if that's good enough your code just got cut by more than half)
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
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the parsing doesn't return a number, it returns a DiceSet object which is a collection of Dice structure
Both DiceSet and Dice have a Roll() method and a nice ToString() implementation
It might be an evaluator. But it evaluate to an object, not a simple number.
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Okay, that's fine, it just means the Eval method is more like a BuildDice method
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
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using (var x = ....) is your friend!
try {} finally {} too
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can i get an amen over here?
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
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