How to limit the amount of concurrent async I/O operations?

Question

// let\'s say there is a list of 1000+ URLs
string[] urls = { \"http://google.com\", \"http://yahoo.com\", ... };

// now let\'s send HTTP requests to each of these          


        

Answer 1

Use MaxDegreeOfParallelism, which is an option you can specify in Parallel.ForEach():

var options = new ParallelOptions { MaxDegreeOfParallelism = 20 };

Parallel.ForEach(urls, options,
    url =>
        {
            var client = new HttpClient();
            var html = client.GetStringAsync(url);
            // do stuff with html
        });