Comments for The Missing Docs .Net

Comment on BindingList does not scale… by Tilps

Tilps — Fri, 04 May 2012 09:29:23 +0000

I won’t go into the specifics, but yes it is a lot of updates. The vast majority of them will be of no use to the user, but any specific one could be – depending on where the user is looking. Yes there could be more complex design strategies which work better, and if the number of changes gets a lot worse it would be crazy not to investigate them – but for the point I am at, a simple replacement of BindingList fixes its scaling problem and gives me plenty of scope for even more updates.

Comment on BindingList does not scale… by Brendan

Brendan — Thu, 03 May 2012 23:32:00 +0000

Are you saying you have in the region of 5K changes per second and you wish to show these “live”? This sounds more like an animation than a data binding.

Comment on BindingList does not scale… by Tilps

Tilps — Thu, 03 May 2012 12:37:43 +0000

Lets drop that size back to 100k elements to be more reasonable. Now your updates only take 1 milisecond each.
If you have 1 update per minute for each element, you are using 150% cpu. That is only 1 update a minute per element.
Drop it back to 10k elements, definitely not uncommon at all, now you can do 1 update per element every second.
In the high performance environments I’m in, 5 updates per second per element on average, is probably more likely (and desired to be shown, so batching the event raising in the back-end won’t help). I might be able to manage 3k elements max, and that is pegging 1 cpu completely just passing the events through the binding list. That doesn’t account for any drawing cost for the UI, any ability for the user to perform actions if there is some small extra high spike of activity.

And this 100% cpu usage can be dropped to practically 0, just by taking a small hit to memory overhead and using the proper data structure.

Comment on BindingList does not scale… by Brendan

Brendan — Thu, 03 May 2012 01:52:30 +0000

I am not sure I see this. Since the underlying collection will be implemented as a linear array, if the collection contains a reference type with default equality, walking the list should be fairly efficient. On my machine (64 bit, 2GHz) a binding list with 10 million items can raise an event on the last item in about 100msec, which does not seem terrribly slow to me for something binding to the UI.

Comment on Expression is Interesting by Alex

Alex — Sun, 12 Feb 2012 01:26:30 +0000

Nifty!

Comment on List.Contains Considered Harmful by Tilps

Tilps — Thu, 10 Nov 2011 10:25:47 +0000

I’d still rather they used the right data structure in the first place instead

Comment on List.Contains Considered Harmful by Pete

Pete — Thu, 10 Nov 2011 09:27:09 +0000

“If we forced everyone to write the double nested loop…” Sadly, I think if we forced everyone to write double nested loops then that’s exactly what they’d do.

What would be nice is if there was an ICollection.AddRangeDistinct extension method, or something like that, where you could pass in an enumerable and have it add items to the collection that aren’t already there. (And presumably it would do the ‘right thing’.)

Comment on List.Contains Considered Harmful by Alex

Alex — Wed, 09 Nov 2011 21:23:05 +0000

Guilty and noted.

Comment on WindowsIdentity by Josh

Josh — Thu, 20 Oct 2011 21:05:34 +0000

Hey Tilps,

I actually just found the issue and since I posted the problem, I figured I’d post the solution.

The WindowsIdentity.GetCurrent() returns a WindowsIdentity. The code example on MSDN was calling WindowsIdentity.GetCurrent().Name and posting it to the console. This call to GetCurrent() still creates an object in memory and since we don’t have a reference we can’t properly dispose of it.

To remedy this, every time the example used GetCurrent().Name, I stored the WindowsIdentity reference, used its Name property, then called Dispose() on it. If you re-use the same reference for each of the three calls, then you must call Dispose() in between each re-assignment or a reference will be left in memory.

Sorry about the posts but I hate to post a question and not post an answer for future blog readers!

Comment on WindowsIdentity by Tilps

Tilps — Thu, 20 Oct 2011 20:50:49 +0000

I don’t have anything useful for you sorry. Without knowing how the profiler determines the scenario I can’t be sure, but it sounds like a false positive, or a miss identification of the location of allocation of the WindowsIdentity object which is not being disposed. (Maybe it isn’t even in your code.)