public void MultiThreadEnqueue()
{
const int capacity = 1000000;
const int threadsCount = 100;
const int count = capacity / threadsCount;
var target = new ConcurrentPriorityQueue<DateTime>();
var execStats = new ExecWithStats[threadsCount];
var watcher = new Stopwatch();
// several threads enqueue elements
watcher.Start();
Parallel.For(0, threadsCount, index =>
{
execStats[index] = new ExecWithStats(string.Format("Add {0}", count), count, () => target.Add(new DateTime()));
execStats[index].Exec();
});
watcher.Stop();
Assert.AreEqual(capacity, target.Count);
Console.WriteLine("{0} threads each enqueue {1} elements. total time: {2}\n", threadsCount, count, watcher.Elapsed);
ExecWithStats.OutputStatsSummary(execStats);
// several threads dequeue elements
watcher.Start();
Parallel.For(0, threadsCount, index =>
{
execStats[index] = new ExecWithStats(string.Format("Take {0}", count), count, () => target.Take());
execStats[index].Exec();
});
watcher.Stop();
Assert.AreEqual(0, target.Count);
Console.WriteLine("\n{0} threads each dequeue {1} elements. total time: {2}\n", threadsCount, count, watcher.Elapsed);
ExecWithStats.OutputStatsSummary(execStats);
}
public void RaceWithStats()
{
const int capacity = 1000000;
const int threadsCount = 100;
const int count = capacity / threadsCount;
var target = new ConcurrentPriorityQueue<DateTime>();
var execStats = new List<ExecWithStats>();
var threadWait = new CountdownEvent(threadsCount);
// odd threads will enqueue elements, while even threads will dequeue
// obviously there will be a race condition and especially in the beginning dequeue will throw, because queue will often be empty
// the total number of exceptions on dequeue threads will correspond the the number of items left in the queue
for (var i = 0; i < threadsCount; i++)
{
ExecWithStats exec;
if (i % 2 != 0)
{
exec = new ExecWithStats(string.Format("Add {0} elements", count), count, () => target.Add( new DateTime()), threadWait);
}
else
{
exec = new ExecWithStats(string.Format("Take {0} elements", count), count, () => target.Take(), threadWait);
}
execStats.Add(exec);
var thread = new Thread(() => exec.Exec());
thread.Start();
}
// Wait for all threads in pool to calculate.
threadWait.Wait();
// Output stats summary
ExecWithStats.OutputStatsSummary(execStats);
// Output queue state
Console.WriteLine("Queue count:{0}, capacity:{1}", target.Count, target.Capacity);
// Un-comment for a detailed list of stats
//Console.WriteLine("---------------------");
//foreach (var execStat in execStats)
//{
// var stats = execStat.GetStats();
// Console.WriteLine("Name:{0}, Min: {1}, Median: {2}, Max {3}, Exceptions: {4}", stats.Name, stats.Min, stats.Med, stats.Max, stats.ExceptionsCount);
//}
}
