我有以下代码(从 LINQPad 复制到此处)。显然,我似乎不明白 TPL 是如何工作的,或者代码是垃圾,为什么并行版本比非并行版本运行得慢?
for (int i = 0; i < 100; i++)
{
ParallelOptions ops = new ParallelOptions();
ops.MaxDegreeOfParallelism = Environment.ProcessorCount;
var watch = Stopwatch.StartNew();
Parallel.ForEach<int>(Enumerable.Range(1, 10000000), ops, x => { int y = x + 1; });
watch.Stop();
Console.WriteLine("Parallel: {0}", watch.Elapsed.TotalSeconds);
watch = Stopwatch.StartNew();
foreach (var x in Enumerable.Range(1, 10000000))
{
int y = x + 1;
}
watch.Stop();
Console.WriteLine("Non-parallel: {0}\n", watch.Elapsed.TotalSeconds);
}
前 10 个结果:
并行:0.1991644
非平行:0.0466178
并行:0.1723428
非平行:0.0447134
并行:0.1141791
非平行:0.0444557
并行:0.1758878
非平行:0.0444636
并行:0.1687637
非平行:0.0444338
并行:0.1677679
非平行:0.0445771
并行:0.1191462
非平行:0.0446116
并行:0.1702483
非平行:0.0454863
并行:0.1143605
非平行:0.0451731
并行:0.2155218
非平行:0.0450392