c# - Is it possible to limit the number of web request per second? -

hi spidering site , reading contents.i want keep request rate reasonable. approx 10 requests per second should ok.currently 5k request per minute , causing security issues looks bot activity. how this? here code

protected void iterareitems(list<item> items) {     foreach (var item in items)     {         getimagesfromitem(item);          if (item.haschildren)         {             iterareitems(item.children.tolist());         }     } }  protected void getimagesfromitem(item childitems) {     var document = new htmlweb().load(completeurl);     var urls = document.documentnode.descendants("img")                 .select(e => e.getattributevalue("src", null))                 .where(s => !string.isnullorempty(s)).tolist(); } 

you need system.threading.semaphore, using can control max concurrent threads/tasks. here example:

var maxthreads = 3; var semaphore = new semaphore(maxthreads, maxthreads);  (int = 0; < 10; i++)    //10 tasks in total {     var j = i;     task.factory.startnew(() =>     {         semaphore.waitone();         console.writeline("start " + j.tostring());         thread.sleep(1000);         console.writeline("end " + j.tostring());         semaphore.release();     }); } 

you can see @ 3 tasks working, others pending semaphore.waitone() because maximum limit reached, , pending thread continue if thread released semaphore semaphore.release().