Re: Optimize the maximum number of threads - C# Discussion Boards

BobJanova25-Jul-11 23:54

BobJanova

25-Jul-11 23:54

The maximum number of threads which can be executing at once is the number of cores available. (Any more than that and you are time slicing.) Threads which are in waits don't count (including asynchronous UI/network calls). Threads are relatively cheap* to create so there is no problem with having your pool, say, twice the size of the maximum number of simultaneous threads.

Once you start getting into large scale multithreading, though, your performance issues are not related to full use of the CPU, but marshalling shared data, synchronisation between threads and making best use of the cores' caches. Optimising your data partitioning is likely to be a better place to gain speed than the thread count.

(*: Relatively. Don't create 200 threads. But a modern OS can handle 20 threads from your application without noticing.)

Dave Kreskowiak26-Jul-11 1:59

26-Jul-11 1:59

BobJanova wrote:
Threads are relatively cheap* to create

Actually, threads are very expensive to create. They take a long to time spin up and, by default in .NET, every thread comes with a price of 1MB of memory for stack space.

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BobJanova26-Jul-11 7:33

BobJanova

26-Jul-11 7:33

'A long time' is a few milliseconds and 1MB is trivial on a machine with gigabytes to play with. As long as you're using them to actually do something useful, the overhead of starting a thread is irrelevant compared to the time and memory actually processing data. They are 'expensive' on one scale, but in terms of real applications on a typical desktop or server configuration, as long as you don't go nuts (hundreds), they're so cheap it doesn't matter.

If you start dealing with mobile or embedded devices then yes, it suddenly becomes something you must think carefully about again.

Dave Kreskowiak26-Jul-11 8:58

26-Jul-11 8:58

If you're spinning up a few threads, sure, it doesn't really matter.

But when noob's start spinning up a couple of hundred of them, or create threads that take longer to spin up than the code they're executing, or start cranking out threads out of a loop, the costs escale dramatically.

Me, I know enough to use threads out the pool or start up just enough to do the job and recycle them myself.

and not every machine has GBs of RAM to play with. Most of the machines around here where I work are 512MB.

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BobJanova26-Jul-11 10:21

BobJanova

26-Jul-11 10:21

Then I think we agree Smile | :)

. (My initial answer said 'cheap is relative, don't start 200' because yeah, that's dumb.) I think it's better to have a thread pool that is possibly too big by a factor of 2 or so (i.e. 15-20 on an 8 core machine) than risk not making use of all the cores you want, if it's the kind of app where you'd be asking about optimising that number instead of letting the framework pick a good one.

Dave Kreskowiak26-Jul-11 10:32

Sorting on column, using mvccontrib lib [modified]

26-Jul-11 10:32

Yeah, we're on the same page.

I've seen crap code where they're launching thread after thread after thread (one per record!) and wondering why the app performs like crap or ends up crashing the machine entirely.

I tend to preach an over-abundance of caution around here (where I work) when helping people with their code. Spawning/Using a new thread/threadpool should be the last thing you think of if you want your code to run faster.

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omgerik25-Jul-11 22:42

omgerik

25-Jul-11 22:42

Ok, my first time here, don't kill me if I posted in the wrong forum. Anyway.

I have two questions, both regarding sorting a grid in my MVC3 application.

This is what my grid looks like (column names are in swedish):

@(
    Html.Grid<ContactListItem>(Model.Contacts)
        .Sort(Model.GridSortPageOptions)
        .Columns(column =>
        {
            column.For(x => x.Id).Named("Id").SortColumnName("Id");
            column.For(x => x.FirstName).Named("Förnamn").SortColumnName("FirstName");
            column.For(x => x.LastName).Named("Efternamn").SortColumnName("LastName");
            column.Custom(x =>
                {
                    if (x.Company == null) return "Oknuten kontakt"; 
                    else return Html.ActionLink(x.Company.CompanyName, "Show", new { controller = "Company", id = x.Company.Id });
                }).Named("Företag").SortColumnName("CompanyName");
            column.For(x => x.MobilePhone).Named("Mobil").Sortable(false); ;
            column.For(x => x.Telephone).Named("Telefon").Sortable(false); ;
            column.For(x => x.Email).Named("E-post").Sortable(false); ;
            column.For(x => x.IsContactPerson ? "X" : "").Named("Kontaktperson").SortColumnName("IsContactPerson");
            column.For(x => x.IsInvoiceReference ? "X" : "").Named("Fakturareferens").SortColumnName("IsInvoiceReference");
            column.For(x => Html.ActionLink("Ändra", "EditContact", new { controller = "Contact", contactId = x.Id, caller = "contactlist" })).Named("Ändra").Sortable(false);
        })
)

1) As you might figure, "Company" is a sub property of Contact. When I sort on the Company field, it automatically sorts on the ID property of Company. However, I want it to sort based on the name of the company. How can I use SortColumnName for this? Is it even possible? If it is of any importance, I use Fluent NHibernate. A quick solution would be to add an additional property ("CompanyName") to my domain object, but that would be REALLY ugly.

2) When I hit one of the column names in order to sort, a new label appears next to the column name, saying "(asc)" or "(desc)", depending what way it sorts the items. I would like to be able to change this text to either an other language or to an image (like a tiny arrow pointing up/down).

Thank you!

Edit: spelling >_>

/Erik

What does Abraham mean?

modified on Tuesday, July 26, 2011 6:13 AM

Re: Sorting on column, using mvccontrib lib

omgerik26-Jul-11 2:08

omgerik

26-Jul-11 2:08

Ok, so, my second question was answered by a colleague. Simply, these two lines had to be located:

thead th.sort_asc a:after {content: " (asc) ";}
thead th.sort_desc a:after {content: " (desc) ";}

The css property "content" confused me since I had never seen it before. Neither "(asc)" or "(desc)" would show up in the page source in the web browser and I couldn't find it using the developer tools in Chrome. However, the content property is handy and I could simple change the asc/desc text to utf8 arrow symbols Smile | :)

Question no.1 remains unsolved. I think I will have to do quite a bit of hacking to solve it. If I solve it before someone else I'll post my findings here.

Edit: spelling again..

What does Abraham mean?

Creat New Security Group At AD

treuveni25-Jul-11 21:33

treuveni

25-Jul-11 21:33

Hi,

I'm trying to add new group,
but getting an error:
error (0x80005000)

this is my code-

<br />
/// <summary><br />
 /// Creates a new group in Active Directory<br />
 /// </summary><br />
 /// <param name="sOU">The OU location you want to save your new Group</param><br />
 /// <param name="sGroupName">The name of the new group</param><br />
 /// <param name="sDescription">The description of the new group</param><br />
 /// <param name="oGroupScope">The scope of the new group</param><br />
 /// <param name="bSecurityGroup">True is you want this group <br />
 /// to be a security group, false if you want this as a distribution group</param><br />
 /// <returns>Returns the GroupPrincipal object</returns><br />
 public GroupPrincipal CreateNewGroup(string sOU, string sGroupName, <br />
	string sDescription, GroupScope oGroupScope, bool bSecurityGroup)<br />
 {<br />
 PrincipalContext oPrincipalContext = GetPrincipalContext(sOU);<br />
<br />
 GroupPrincipal oGroupPrincipal = new GroupPrincipal(oPrincipalContext, sGroupName);<br />
 oGroupPrincipal.Description = sDescription;<br />
 oGroupPrincipal.GroupScope = oGroupScope;<br />
 oGroupPrincipal.IsSecurityGroup = bSecurityGroup;<br />
 oGroupPrincipal.Save();<br />
<br />
 return oGroupPrincipal;<br />
 }<br />
<br />
/// <summary><br />
 /// Gets the principal context on specified OU<br />
 /// </summary><br />
 /// <param name="sOU">The OU you want your Principal Context to run on</param><br />
 /// <returns>Returns the PrincipalContext object</returns><br />
 public PrincipalContext GetPrincipalContext(string sOU)<br />
 {<br />
 PrincipalContext oPrincipalContext = <br />
	new PrincipalContext(ContextType.Domain, sDomain, sOU, <br />
	ContextOptions.SimpleBind, sServiceUser, sServicePassword);<br />
 return oPrincipalContext;<br />
 }<br />

The code thaken from here-
Everything in Active Directory via C#.NET 3.5 (Using System.DirectoryServices.AccountManagement)[^]

i think the error comming from here-

GroupPrincipal oGroupPrincipal = new GroupPrincipal(oPrincipalContext, sGroupName);<br />

what i'm doing wrong? Frown | :(

Shameel25-Jul-11 23:54

Shameel

25-Jul-11 23:54

You should have received an associated error message. Post it here.

treuveni25-Jul-11 23:57

treuveni

25-Jul-11 23:57

System.DirectoryServices.AccountManagement.PrincipalOperationException was caught
Message=Unknown error (0x80005000)
Source=System.DirectoryServices.AccountManagement
ErrorCode=-2147463168

Shameel27-Jul-11 1:52

Shameel

27-Jul-11 1:52

This[^] discussion seems to be related to your problem.

Dave Kreskowiak26-Jul-11 1:53

26-Jul-11 1:53

Chances are you passed in an invalid ADS pathname to one of your functions.

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