public static async Task ParallelForEachAsync <T>(
this IEnumerable <T> source, Func <T, int, Task> asyncAction, int?maxDegreeOfParallelism = null)
{
if (maxDegreeOfParallelism == 1)
{
await source.ForEachAsync(asyncAction);
return;
}
maxDegreeOfParallelism ??= Math.Min(Environment.ProcessorCount, 512);
OrderablePartitioner <T> partitioner = source is IList <T> list
? Partitioner.Create(list, loadBalance : true)
: Partitioner.Create(source, EnumerablePartitionerOptions.NoBuffering);
await Task.WhenAll(partitioner
.GetPartitions(maxDegreeOfParallelism.Value)
.Select((partition, index) => Task.Run(async() =>
{
while (partition.MoveNext())
{
await asyncAction(partition.Current, index);
}
})));
}
public static async Task ParallelForEachAsync <T>(
this IEnumerable <T> source, Func <T, Task> asyncAction, int?maxDegreeOfParallelism = null)
{
maxDegreeOfParallelism ??= DefaultMaxDegreeOfParallelism;
if (maxDegreeOfParallelism <= 0)
{
throw new ArgumentOutOfRangeException(nameof(maxDegreeOfParallelism));
}
if (maxDegreeOfParallelism == 1)
{
foreach (T value in source)
{
await asyncAction(value);
}
return;
}
OrderablePartitioner <T> partitioner = source is IList <T> list
? Partitioner.Create(list, loadBalance : true)
: Partitioner.Create(source, EnumerablePartitionerOptions.NoBuffering);
await Task.WhenAll(partitioner
.GetPartitions(maxDegreeOfParallelism.Value)
.Select(async partition =>
{
while (partition.MoveNext())
{
await asyncAction(partition.Current);
}
}));
}
public override IList <IEnumerator <TSource> > GetPartitions(int partitionCount)
{
return(_partitioner.GetPartitions(partitionCount));
}