/// <summary>
/// Non-syncronized access to a float value from multiple threads.
/// In each thread adds 1 to a total value (initially zeroed) specified number of repetition.
/// Returns the total value (will be wrong on multi-CPU machines).
/// RunTime contains the time required for this operation.
/// </summary>
public float SumValuesNoSync(int threadCount, int repetitions)
{
BlockingThreadPool threadPool = new BlockingThreadPool(threadCount);
BlockingThreadPool.JobBase[] works = new BlockingThreadPool.JobBase[threadCount];
for (int t = 0; t < threadCount; ++t)
{
works[t] = new BlockingThreadPool.Job <int>
{
Param1 = repetitions,
Execute = NoSyncWork
};
}
_totalValue = 0;
DateTime startTime = DateTime.Now;
threadPool.ExecuteJobs(works);
RunTime = (DateTime.Now - startTime).TotalSeconds;
return(_totalValue);
}
/// <summary>
/// Run a number of threads doing some repetitive operations.
/// Currently the job is to calculating Fibonacci numbers and storing them in an array.
/// At the end the number of operations per seconds for all threads actually done is returned.
/// This allows to estimate the optimal number of threads to perform some calcluation task.
/// </summary>
/// <param name="threadsCount"></param>
/// <param name="repeatCount"></param>
/// <returns></returns>
public double MultithreadPerformance(int threadsCount, UInt64 repeatCount)
{
BlockingThreadPool threadPool = new BlockingThreadPool(threadsCount);
BlockingThreadPool.Job[] works = new BlockingThreadPool.Job[threadsCount];
for (int w = 0; w < threadsCount; ++w)
{
Work work = new Work(repeatCount);
works[w] = new BlockingThreadPool.Job
{
DoDelegate = work.Execute
};
}
DateTime startTime = DateTime.Now;
threadPool.ExecuteJobs(works);
double workTime = (DateTime.Now - startTime).TotalSeconds;
double repPerSec = ((double)threadsCount * repeatCount) / workTime;
Console.WriteLine(
"MultithreadPerformance treads: {0}, repeatitions/tread: {1:0,0}, work time: {2:0.000} s, rep/s: {3:0,0}",
threadsCount, repeatCount, workTime, repPerSec);
return(repPerSec);
}
private void InternalStop()
{
if (_retrieveThreadPool != null)
{
_retrieveThreadPool.Stop(false);
_retrieveThreadPool = null;
}
if (_imageBoxEnumerator != null)
{
_imageBoxEnumerator.Dispose();
_imageBoxEnumerator = null;
}
}
private void InternalStart()
{
int retrieveConcurrency = Prefetch.Default.RetrieveConcurrency;
if (retrieveConcurrency == 0)
return;
_imageBoxEnumerator = new ViewerFrameEnumerator(ImageViewer,
Math.Max(Prefetch.Default.SelectedWeighting, 1),
Math.Max(Prefetch.Default.UnselectedWeighting, 0),
Prefetch.Default.ImageWindow);
_retrieveThreadPool = new BlockingThreadPool<Frame>(_imageBoxEnumerator, RetrieveFrame);
_retrieveThreadPool.ThreadPoolName = "Retrieve";
_retrieveThreadPool.Concurrency = retrieveConcurrency;
_retrieveThreadPool.ThreadPriority = ThreadPriority.BelowNormal;
_retrieveThreadPool.Start();
}
public double ComputeDominationLoss(double[] scores)
{
int chunkSize = 1 + Dataset.NumQueries / BlockingThreadPool.NumThreads; // Minimizes the number of repeat computations in sparse array to have each thread take as big a chunk as possible
double totalOutput = 0.0;
var _lock = new Object();
for (int queryBegin = 0; queryBegin < Dataset.NumQueries; queryBegin += chunkSize)
{
BlockingThreadPool.RunOrBlock(delegate(int startQuery, int endQuery)
{
double output = 0.0;
for (int query = startQuery; query <= endQuery; query++)
{
int begin = Dataset.Boundaries[query];
int end = Dataset.Boundaries[query + 1];
if (end - begin <= 1)
{
continue;
}
int bestDoc = _bestDocsPerQuery.BestDocs[query];
int secondBestDoc = _bestDocsPerQuery.SecondBestDocs[query];
double bestDocScore = scores[bestDoc];
double secondBestDocScore = scores[secondBestDoc];
// find max score
double max = double.NegativeInfinity;
double maxNotBest = double.NegativeInfinity;
for (int d = begin; d < end; ++d)
{
if (max < scores[d])
{
max = scores[d];
}
if (d != bestDoc && maxNotBest < scores[d])
{
maxNotBest = scores[d];
}
}
// sum of exponents and sum of all but best
double sum = 0.0;
double sumAllButBest = 0.0;
for (int d = begin; d < end; ++d)
{
sum += Math.Exp(scores[d] - max);
if (d != bestDoc)
{
sumAllButBest += Math.Exp(scores[d] - maxNotBest);
}
}
output += max - bestDocScore + Math.Log(sum) + 0.5 * (maxNotBest - secondBestDocScore + Math.Log(sumAllButBest));
}
lock (_lock)
{
totalOutput += output;
}
}, queryBegin, Math.Min(queryBegin + chunkSize - 1, Dataset.NumQueries - 1));
}
BlockingThreadPool.BlockUntilAllWorkItemsFinish();
return(totalOutput);
}
/// <summary>
/// Make segmens of different sizes, dividing array in the following proportion: 1, 2, 4, etc.
/// This allows to test if the thread pool uses free threads to process pending jobs.
/// Due to different segment sizes the better performance in this test will be reached with the
/// greater number of segments, because idle time of threads will be lower.
/// </summary>
void FillArray(int size, int numThreads, int numSegments, int repetitions)
{
BlockingThreadPool pool = new BlockingThreadPool(numThreads);
_array = new byte[size];
int [] segmentSizes = new int[numSegments];
int curSize = 0;
double factor = size / (Math.Pow(2, numSegments) - 1);
for (int s = 0; s < numSegments - 1; ++s)
{
segmentSizes[s] = (int)(Math.Pow(2, s) * factor);
curSize += segmentSizes[s];
}
segmentSizes[numSegments - 1] = size - curSize;
DateTime start = DateTime.Now;
int begin;
for (int r = 0; r < repetitions; ++r)
{
BlockingThreadPool.JobBase[] jobs = new BlockingThreadPool.JobBase[numSegments];
begin = 0;
for (int w = 0; w < numSegments; ++w)
{
Parameters p = new Parameters {
Start = begin, Count = segmentSizes[w], Value = w
};
if (w == numSegments - 1)
{
p.Count = size - p.Start;
}
jobs[w] = new BlockingThreadPool.Job <Parameters>
{
Param1 = p,
Execute = FillArrayThreadFunc
};
begin += p.Count;
}
pool.ExecuteJobs(jobs);
}
double time = (DateTime.Now - start).TotalMilliseconds;
Console.WriteLine("Array size: {0:0,0}, threads: {1,3}, segments: {2,3}, repeats: {3,3}, time: {4:0.0} ms, el/s: {5:#,#}",
size, numThreads, numSegments, repetitions, time,
(double)size * repetitions / (time * 0.001));
// Now verify values.
pool.Dispose();
begin = 0;
for (int s = 0; s < numSegments; ++s)
{
int end = begin + segmentSizes[s];
for (int i = begin; i < end; ++i)
{
// Check before assert, it is much faster.
if (s != _array[i])
{
Assert.AreEqual(s, _array[i]);
}
}
begin = end;
}
}