Q&A Reader emails about .NET memory leaks and random questions

re: Q&A Reader emails about .NET memory leaks and random questions

Keith Kaminski — Tue, 16 Sep 2008 22:23:35 GMT

Thanks for answering my question, Tess. I submitted the question about debugging managed code in IE. After digging through about two different memory dumps from the machine, I found that only 3-4 of them had any threads with managed code... and those threads looked like they were in the middle of performing a "SafeNativeMethod" call like this:

0x07b7afe0 0x7c8285ec [FRAME: NDirectMethodFrameStandalone] [DEFAULT] Boolean System.Windows.Forms.SafeNativeMethods.SetWindowPos(ValueClass System.Runtime.InteropServices.HandleRef,ValueClass System.Runtime.InteropServices.HandleRef,I4,I4,I4,I4,I4)

I'm at a total loss to figure out what the problem is, so I've gone ahead and opened up a ticket with Microsoft about it.

I very much appreciate that you responded to my question on your blog!

- Keith

re: Q&A Reader emails about .NET memory leaks and random questions

Keith Kaminski — Tue, 16 Sep 2008 22:42:22 GMT

Also, to answer your question...

I've monitored the network traffic with Fiddler and used SQL Profiler to make sure my control wasn't doing some kind of processing when IE hung. The freeze always happens before or after every network\SQL call has completed... it never freezes up in the middle of processing.

My thought right now is that the freeze is related to rendering. I feel like something is in a deadlock, but I just can't figure out what it could be. Syncblk doesn't show locks in any of my 22 memory dumps, and the !threads command shows a lock count of 0 for everything.

I'll admit to being somewhat new to debugging via memory dumps, so hopefully the folks at Microsoft can help me figure this one out!

Thanks again!

- Keith

re: Q&A Reader emails about .NET memory leaks and random questions

Daniel Puzey — Wed, 17 Sep 2008 15:54:28 GMT

Regarding dependency properties....

The dependency property itself is a static property of the class, and any instance property is a wrapper that calls the dependency property, making this trickier than it looks.

However, you can only use a DependencyProperty on a class that derives from DependencyObject. From Reflector, you can see that there's the following definition in the DependencyObject class:

private IDictionary<DependencyProperty, object> dependencyPropertyValues;

... so I'd guess that's where the values are stored. Remember though that these might not be the actual values - they might be a binding object that calculates the value. Sadly I haven't had time to look any deeper yet...

re: Q&A Reader emails about .NET memory leaks and random questions

James — Wed, 17 Sep 2008 17:54:11 GMT

Thanks for responding to my e-mail (about the memory leak). I'm still working on it and will comment here when I figure it out.

On another note, in reference to the "Fragmentation of the LOH" e-mail, I had read an article regarding the 1.0 framework that said the LOH is allocated but never really freed-up. The objects might be removed and the space can be used again for the application, but the memory is not freed-up for the OS.

Do you know if that has changed?

Does memory allocated for the LOH ever get released back to the OS?

Thanks,

James

re: Q&A Reader emails about .NET memory leaks and random questions

Tess — Wed, 17 Sep 2008 17:58:20 GMT

yes, when the segment no longer has any objects... this was changed in 2.0 i believe

re: Q&A Reader emails about .NET memory leaks and random questions

joydip roy chowdhury — Thu, 18 Sep 2008 16:18:39 GMT

Though the explanation is rather tricky,it is good.

I would request you to kindly explain it with the help of examples .So that it is easier to understand this subject.

re: Q&A Reader emails about .NET memory leaks and random questions

joydip roy chowdhury — Thu, 18 Sep 2008 16:18:44 GMT

Though the explanation is rather tricky,it is good.

I would request you to kindly explain it with the help of examples .So that it is easier to understand this subject.

Interesting Finds: 2008.09.15~2008.09.21

gOODiDEA.NET — Mon, 22 Sep 2008 01:47:52 GMT

Other Don't Tell Me "How", Tell me "What" Microsoft Network Monitor 3.2 .NET MSDN

re: Q&A Reader emails about .NET memory leaks and random questions

Nick Parker — Thu, 02 Oct 2008 02:57:30 GMT

I have a question about % time in GC and the 3 generations. I have an app that has a very low % of time in the GC, but the ratio between the generations doesnt seem to be ideal. The average % of time in the GC is 2.27%, but the ratio between gen0 and gen1 is .65, and the ratio between gen1 and gen2 is .19. Should i be looking further, or since the % is so low, just ignore the ratio?

Thanks,

Nick