Question

I have a Semaphore that suspose to limit to 3, however, this just keeps calling as many as it wants. I’m assuming it’s because I use (1000). However, when I try just () it will never pass the WaitOne i’m not sure what to do here.

private static Semaphore _pool;
_pool = new Semaphore(0, 3);
var options = new ParallelOptions();
options.MaxDegreeOfParallelism = 1;
Parallel.ForEach(urlTable.AsEnumerable(),options, drow =>
{
    using (var WCC = new MasterCrawlerClass())
    {
                ActiveThreads++;
                _pool.WaitOne(1000);
                Console.WriteLine("Active Thread #: " + ActiveThreads);
                WCC.MasterCrawlBegin(drow);
                Console.WriteLine("Done Crawling a datarow");
                ActiveThreads--;
                _pool.Release();

    }
});

Answer 1

You are miscontructing the semaphore. It should be _pool = new Semaphore(3, 3); Doing that will also eliminate the need to pass in a timeout parameter to WaitOne().

The first parameter is the initial number of requests that may be granted before blocking, so passing 0 means any subsequent calls to WaitOne() will immediately block.