wpf - Parallel.ForEach hangs the layout in MVVM while working on big Lists -

i have generic list contains 1100 elements. 10 of these elements contain 1000 elements each (of same type). elements bound ui datagrid. itrating list takes long time 5-6 seconds (because properties manipulate in iterations databound datagrid properties).

here iteration code:

parallel.foreach(this.allparameters, par => {   foreach (parameter subpar in par.wrappedsubparameters)   {     subpar.isselected = false;   }   par.isselected = false; }); 

the code snippet in xaml looks like:

  <datagrid.rowstyle>      <style targettype="{x:type datagridrow}" basedon="{staticresource {x:type datagridrow}}">        <setter property="isselected" value="{binding isselected, mode=oneway}" /> 

as in previous question suggested use parallel iteration, hangs ui , never returns back. how can suspend ui before doing iterations in mvvm. doing code in right way? please suggesst. thanks

you can find answer here: link thing is, cant call parallel.foreach on ui thread. if not sure current thread, can use method this:

    public static bool checkisrunningonuithread()     {         if (application.current == null) return false;         var dispatcher = application.current.dispatcher;         if (dispatcher==null) return false;         return dispatcher.checkaccess();     }