例子1
using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
namespace ConsoleApp
{
class Program
{
static void Main(string[] args)
{
var dic = new ConcurrentDictionary<int, int>();
for (int i = 0; i < 6; i++)
{
Console.WriteLine(i + " count");
runInNewThread(i);
}
void runInNewThread(int i)
{
var thread = new Thread(para => dic.GetOrAdd(1, _ => getNum((int)para)));
thread.Start(i);
}
int getNum(int i)
{
Console.WriteLine($"Factory invoke. got {i}");
return i;
}
Console.ReadKey();
}
}
-
运行结果可能为以下之一
例1-1
例1-2
例1-3
例1-4
例1-5
例子2
using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
namespace ConsoleApp
{
class Program
{
static void Main(string[] args)
{
ConcurrentDictionary<int, int> cd = new ConcurrentDictionary<int, int>();
// Bombard the ConcurrentDictionary with 10000 competing AddOrUpdates
Parallel.For(0, 10000, i =>
{
// Initial call will set cd[1] = 1.
// Ensuing calls will set cd[1] = cd[1] + 1
cd.AddOrUpdate(1, 1, (key, oldValue) => oldValue + 1);
});
Console.WriteLine("After 10000 AddOrUpdates, cd[1] = {0}, should be 10000", cd[1]);
// Should return 100, as key 2 is not yet in the dictionary
int value = cd.GetOrAdd(2, (key) => 100);
Console.WriteLine("After initial GetOrAdd, cd[2] = {0} (should be 100)", value);
// Should return 100, as key 2 is already set to that value
value = cd.GetOrAdd(2, 10000);
Console.WriteLine("After second GetOrAdd, cd[2] = {0} (should be 100)", value);
Console.ReadKey();
}
}
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运行结果如下
例2
例子3
using System;
using System.Collections.Concurrent;
using System.Threading;
using System.Threading.Tasks;
namespace ConsoleApp
{
class Program
{
static void Main(string[] args)
{
var task1 = Task.Run(() => PrintValue("JeffckWang"));
var task2 = Task.Run(() => PrintValue("cnblogs"));
Task.WaitAll(task1, task2);
PrintValue("JeffckyWang from cnblogs");
Console.WriteLine($"Run count: {_runCount}");
Console.ReadKey();
}
private static readonly ConcurrentDictionary<string, string> _dictionary
= new ConcurrentDictionary<string, string>();
private static int _runCount = 0;
public static void PrintValue(string valueToPrint)
{
var valueFound = _dictionary.GetOrAdd("key",
x =>
{
Interlocked.Increment(ref _runCount);
Thread.Sleep(100);
return valueToPrint;
});
Console.WriteLine(valueFound);
}
}
}
-
运行结果可能为以下之一
例3-1
例3-2
例子4
using System;
using System.Collections.Concurrent;
using System.Threading;
using System.Threading.Tasks;
namespace ConsoleApp2
{
class Program
{
static void Main(string[] args)
{
var task1 = Task.Run(() => PrintValue("JeffckWang"));
var task2 = Task.Run(() => PrintValue("cnblogs"));
Task.WaitAll(task1, task2);
PrintValue("JeffckyWang from cnblogs");
Console.WriteLine($"Run count: {_runCount}");
Console.ReadKey();
}
private static int _runCount = 0;
private static readonly ConcurrentDictionary<string, Lazy<string>> _lazyDictionary
= new ConcurrentDictionary<string, Lazy<string>>();
public static void PrintValue(string valueToPrint)
{
var valueFound = _lazyDictionary.GetOrAdd("key",
x => new Lazy<string>(
() =>
{
Interlocked.Increment(ref _runCount);
Thread.Sleep(100);
return valueToPrint;
}));
Console.WriteLine(valueFound.Value);
}
}
}
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运行结果可能为以下之一
例4-1
例4-2
具体过程分析请看参考
