正确有效地使用. asparallel()与linq
本文关键字:linq asparallel 有效地 | 更新日期: 2023-09-27 18:06:05
我有一个元组,我用LINQ对它进行迭代
List<Tuple<string[], double[]>> tt = new List<Tuple<string[], double[]>>();
var t1 = new Tuple<string[], double[]>(
new string[] { "java", "c#", "nn" },
new double[] { 2, 3, 0 });
var t2 = new Tuple<string[], double[]>(
new string[] { "java", "c#", "nn" },
new double[] { 0, 3, 1 });
var t3 = new Tuple<string[], double[]>(
new string[] { "java", "c#", "nn" },
new double[] { 2, 1, 0 });
tt.Add(t1);
tt.Add(t2);
tt.Add(t3);
var XX = (from tuples in tt
let rows = tuples.Item2.ToArray()
let result = rows.Select(x => x/rows.Count(i => i != 0)).ToArray()
select new Tuple<string[], double[]>(tuples.Item1, result)
).ToList();
如果我想使用.Asparallel
,我可以使用以下方法之一:
我可以在遍历列表时添加它:
var XX = (from tuples in tt
.AsParallel() //Parallel added here
let rows = tuples.Item2.ToArray()
let result = rows.Select(x => x/rows.Count(i => i != 0)).ToArray()
select new Tuple<string[], double[]>(tuples.Item1, result)
).ToList();
我可以在使用.ToArray()
或.ToList
转换东西时添加它
var XX = (from tuples in tt
let rows = tuples.Item2.ToArray()
let result = rows.Select(x => x / rows.Count(i => i != 0)).AsParallel().ToArray() //Parallel added right here
select new Tuple<string[], double[]>(tuples.Item1, result)
).ToList();
.Asparallel
最有效的利用方法是什么?所有这些方法都没有错误,但我不确定它们是否会影响性能。
像这样添加.Asparallel
是一个坏主意吗?:
var XX = (from tuples in tt
.AsParallel() //added here
let rows = tuples.Item2.AsParallel().ToArray() //here
let result = rows.Select(x => x / rows.Count(i => i != 0)).AsParallel().ToArray()//here
select new Tuple<string[], double[]>(tuples.Item1, result)
).AsParallel().ToList(); // and here
您应该在启动LINQ查询时在from
子句中添加AsParallel
。这将使两个let
语句并行执行,然后在最后调用ToList
时合并在一起。
您也可以在查询中调用Select
之前添加另一个AsParallel
。
var XX = (from tuples in tt.AsParallel()
let rows = tuples.Item2.ToArray()
let result = rows.AsParallel().Select(x => x/rows.Count(i => i != 0)).ToArray()
select new Tuple<string[], double[]>(tuples.Item1, result)
).ToList();
但是,您应该记住AsParallel
有一些开销,因此在某些情况下它可能比常规的非并行处理慢。