private static void PerformSmokeTest(int capacity, int parallelism, TimeSpan duration, Action payload)
{
var semaphore = new LifoSemaphore(capacity);
var tasks = new List <Task>();
var observedParallelism = 0;
for (var i = 0; i < parallelism; i++)
{
tasks.Add(
Task.Run(
async() =>
{
var watch = Stopwatch.StartNew();
while (watch.Elapsed < duration)
{
await semaphore.WaitAsync();
if (Interlocked.Increment(ref observedParallelism) > capacity)
{
throw new Exception($"Violated max allowed parallelism of {parallelism} (observed {observedParallelism})");
}
payload();
Interlocked.Decrement(ref observedParallelism);
semaphore.Release();
}
}));
}
Task.WhenAll(tasks).GetAwaiter().GetResult();
semaphore.CurrentCount.Should().Be(capacity);
semaphore.CurrentQueue.Should().Be(0);
Console.Out.WriteLine($"Success: capacity = {capacity}, parallelism = {parallelism}, duration = {duration}.");
}
public void Benchmark_multi_threaded_speed_vs_SemaphoreSlim(int capacity, int parallelism, int iterations)
{
var slimTimes = new List <double>();
var lifoTimes = new List <double>();
var slimSemaphore = new SemaphoreSlim(capacity, capacity);
var lifoSemaphore = new LifoSemaphore(capacity);
for (var i = 0; i < 5; i++)
{
var watch = Stopwatch.StartNew();
var tasks = new List <Task>();
for (var j = 0; j < parallelism; j++)
{
tasks.Add(
Task.Run(
async() =>
{
for (var k = 0; k < iterations; k++)
{
await slimSemaphore.WaitAsync();
slimSemaphore.Release();
}
}));
}
Task.WhenAll(tasks).GetAwaiter().GetResult();
slimTimes.Add(watch.Elapsed.TotalMilliseconds);
Console.Out.WriteLine($"Slim: {watch.Elapsed.TotalMilliseconds:F2} ms");
}
var avgSlimTime = slimTimes.Average();
Console.Out.WriteLine();
Console.Out.WriteLine($"Slim avg: {avgSlimTime:F2} ms");
Console.Out.WriteLine();
for (var i = 0; i < 5; i++)
{
var watch = Stopwatch.StartNew();
var tasks = new List <Task>();
for (var j = 0; j < parallelism; j++)
{
tasks.Add(
Task.Run(
async() =>
{
for (var k = 0; k < iterations; k++)
{
await lifoSemaphore.WaitAsync();
lifoSemaphore.Release();
}
}));
}
Task.WhenAll(tasks).GetAwaiter().GetResult();
lifoTimes.Add(watch.Elapsed.TotalMilliseconds);
Console.Out.WriteLine($"Lifo: {watch.Elapsed.TotalMilliseconds:F2} ms");
}
var avgLifoTime = lifoTimes.Average();
Console.Out.WriteLine();
Console.Out.WriteLine($"Lifo avg: {avgLifoTime:F2} ms");
Console.Out.WriteLine();
if (avgLifoTime < avgSlimTime)
{
Console.Out.WriteLine($"Winner is LifoSemaphore ({avgSlimTime / avgLifoTime:F2}x)!");
Assert.Pass();
}
else
{
Console.Out.WriteLine($"Winner is SemaphoreSlim ({avgLifoTime / avgSlimTime:F2}x)!");
Assert.Inconclusive();
}
}
public void WaitAsync_should_return_completed_tasks_immediately_until_count_goes_negative()
{
semaphore.WaitAsync().IsCompleted.Should().BeTrue();
semaphore.WaitAsync().IsCompleted.Should().BeTrue();
semaphore.WaitAsync().IsCompleted.Should().BeTrue();
}
public void Lifo()
{
lifoSemaphore.WaitAsync().GetAwaiter().GetResult();
lifoSemaphore.Release();
}