Semaphoreslim locking method

Question

I am using Semaphoreslim to make the "lock" of some methods of my Web-API, until it worked correctly but there are times when these same methods get totally stuck, by Postman when I run gets a loading and after some time returns the error.

Follows the code

public class ApiController : Controller
{
    static SemaphoreSlim semaphoreSlimScheduling = new SemaphoreSlim(1);

    ...//outros métodos

    [HttpPost]
    public async Task<JsonResult> ConfirmScheduling(FormCollection collection)
    {
        try
        {
            await semaphoreSlimScheduling.WaitAsync();

            //código....

            semaphoreSlimScheduling.Release();
            return Json(new { error = false, message = "Sucesso" });
        }
        catch (Exception ex)
        {
            semaphoreSlimScheduling.Release();
            return Json(new { error = true, message = ex.Message });
        }
    }   
}

Just and another method is using Semaphoreslim’s Wait. The other methods I’m not doing this locking. Does anyone have any idea what it might be?

Answer 1

The behavior is correct. When called await semaphoreSlimScheduling.Waitasync() the thread will be suspended until the return of the task. Depending on what you’re doing, it can take a while or even fail to get the lock (Postman intermittence). I suggest two things:

• Set a timeout for the lock (overload of the Waitasync() method), avoiding that the task is waiting infinitely
• Assign Waitasync return and check whether it returns true (lock acquired) or false (lock failure).